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w WM8952 mono adc with microphone pre-amplifier wolfson microelectronics plc to receive regular email updates, sign up at http://www.wolfsonmicro.com/enews pre production, rev 3.1, june 2011 copyright ? 2011 wolfson microelectronics plc description the WM8952 is a low power, high quality mono adc designed for portable applications such as wireless microphones or headsets. the device integrates support for differential or single ended microphone connections. external component requirements are reduced as no separate microphone amplifier is required. an advanced sigma delta converter design is used to give high quality audio at sample rates from 8 to 48ks/s. a selectable high pass filter and four fully-programmable notch filters are also available in the signal path. an advanced mixed signal alc function with noise gate is provided, supporting readback of pga gain during alc operation. the digital audio interface supports a-law and -law companding. an on-chip pll is provided to generate the required master clock from an external reference clock. the pll clock can also be output if required elsewhere in the system. the WM8952 operates at supply voltages from 2.5 to 3.6v, although the digital supplies can operate at voltages down to 1.71v to save power. different sections of the chip can also be powered down under software control using the selectable two or three wire control interface. the device is supplied in a very small w-csp package, offering high levels of functionality in minimum board area, with high thermal performance. features ? mono adc: ? audio sample rates:8, 11.025, 16, 22.05, 24, 32, 44.1, 48khz ? adc snr 94db, thd -80db (?a?-weighted @ 8 ? 48ks/s) ? mic preamps : ? differential or single end microphone interface - programmable preamp gain - pseudo differential inputs with common mode rejection - programmable alc / noise gate in adc path ? low-noise bias supplied for electret microphones ? multiple analog or ?aux? inputs with analogue mixing other features ? programmable high pass filter (wind noise reduction) ? 4 notch filters (narrowband noise suppression) ? on-chip pll ? low power, low voltage - 2.5v to 3.6v (digital: 1.71v to 3.6v) ? 28 ball w-csp (2.59 2.5 0.7mm, 0.4mm pitch) package applications ? headsets ? wireless microphones ? general purpose mono audio adc block diagram
WM8952 pre production w pp, rev 3.1, june 2011 2 table of contents description ................................................................................................................ 1 features...................................................................................................................... 1 applications .............................................................................................................. 1 block diagram .......................................................................................................... 1 table of contents .................................................................................................. 2 pin configuration .................................................................................................... 4 ordering information ........................................................................................... 4 pin description ......................................................................................................... 5 absolute maximum ratings .................................................................................. 6 recommended operating conditions .............................................................. 6 electrical characteristics ............................................................................... 7 terminology ................................................................................................................... ... 8 audio paths overview ............................................................................................ 9 power consumption ............................................................................................. 10 signal timing requirements .............................................................................. 11 system clock timing ..................................................................................................... 11 audio interface timing ? master mode .................................................................. 11 audio interface timing ? slave mode ...................................................................... 12 control interface timing ? 3-wire mode .............................................................. 13 control interface timing ? 2-wire mode .............................................................. 14 device description ................................................................................................ 15 introduction .................................................................................................................. . 15 input signal path ........................................................................................................... 1 6 analogue to digital converter (adc) .................................................................... 22 input limiter / automatic level control (alc) .................................................... 27 digital audio interfaces ............................................................................................. 40 audio sample rates ....................................................................................................... 43 master clock and phase locked loop (pll) ......................................................... 44 companding .................................................................................................................... .. 47 general purpose input/output ................................................................................ 49 control interface ........................................................................................................ 49 3-wire serial control mode ...................................................................................... 51 readback in 3-wire mode ............................................................................................. 51 2-wire serial control mode ...................................................................................... 52 resetting the chip ........................................................................................................ 52 power supplies .............................................................................................................. 5 2 power management ...................................................................................................... 54 pop minimisation ............................................................................................................. 55 thermal shutdown ....................................................................................................... 55 register map ............................................................................................................ 56 register bits by a ddress ... ........................................................................................ 57 digital filter characteristics ........................................................................ 65 terminology ................................................................................................................... . 65 adc filter responses ................................................................................................... 65 highpass filter ............................................................................................................... 66 notch filters and low pass filter ......................................................................... 67 recommended external components ........................................................... 69 package diagram ................................................................................................... 70 important notice ................................................................................................... 71
pre production WM8952 w pp, rev 3.1, june 2011 3 address ....................................................................................................................... ...... 71 revision history ..................................................................................................... 72
WM8952 pre production w pp, rev 3.1, june 2011 4 pin configuration ordering information order code temperature range package moisture sensitivity level package body temperature WM8952ecs/rv -25 c to +85 c 28-ball w-csp (pb-free, tape and reel) msl3 260 o c note: reel quantity: WM8952ecs/rv = 3,500
pre production WM8952 w pp, rev 3.1, june 2011 5 pin description pin (wlcsp) name type description b5 micbias analogue output microphone bias b6 avdd supply analogue supply c6 agnd supply analogue ground d6 dcvdd supply digital supply (core) d5 dbvdd supply digital supply (input/output) e6 dgnd supply digital ground f6 adcdat digital output adc digital audio data output e5 tp test pin connect to ground e3 frame digital input / output adc sample rate clock or frame synch f5 bclk digital input / output digital audio port clock f4 mclk digital input master clock input f3 csb/gpio digital input / output 3-wire control interface chip select or gpio pin e2 sclk digital input control interface clock input f1 sdin digital input / output control interface data input f2 mode/gpio digital input control interface mode selection or gpio pin a1 agnd2 supply analogue ground a2 avdd2 supply analogue supply b4 aux analogue input auxiliary analogue input a4 vmid reference decoupling for midrail reference voltage a5 micn analogue input microphone negative input (common mode) a6 micp analogue input microphone positive input a3, b1, b2, c1, c2, d1, e1 dnc do not connect leave these pins floating
WM8952 pre production w pp, rev 3.1, june 2011 6 absolute maximum ratings absolute maximum ratings are stress ratings only. permanent damage to the device may be caused by continuously operating at or beyond these limits. device functional operating limits and guaranteed performance specifications are given under electrical characteristics at the test conditions specified. esd sensitive device. this device is manufactured on a cmos process. it is therefore generically susceptible to damage from excessive static voltages. proper esd precautions must be taken during handling and storage of this device. wolfson tests its package types according to ipc/jedec j-std-020b for moisture sensitivity to determine acceptable storage conditions prior to surface mount assembly. these levels are: msl1 = unlimited floor life at <30 c / 85% relative humidity. not normally stored in moisture barrier bag. msl2 = out of bag storage for 1 year at <30 c / 60% relative humidity. supplied in moisture barrier bag. msl3 = out of bag storage for 168 hours at <30 c / 60% relative humidity. supplied in moisture barrier bag. the moisture sensitivity level for each package type is specified in ordering information. condition min max dbvdd , dcvdd, avdd supply voltages -0.3v +4.2 voltage range digital inputs dgnd -0.3v 1 dvdd +0.3v 1 voltage range analogue inputs agnd -0.3v 1 avdd +0.3v 1 operating temperature range, t a -25 c +85 c storage temperature prior to soldering 30 c max / 85% rh max storage temperature after soldering -65 c +150 c notes 1. analogue and digital grounds must always be within 0.3v of each other. 2. all digital and analogue supplies are completely independent from each other. recommended operating conditions parameter symbol test conditions min typ max unit digital supply range (core) dcvdd 1.71 3.6 v digital supply voltage (buffer) dbvdd 1.71 3.6 v analogue supplies range avdd, avdd2 1 2.5 3.6 v ground dgnd, agnd, agnd2 0 v notes 1. analogue supply voltage must not be less than the digital supply voltages. 2. dbvdd must be dcvdd
pre production WM8952 w pp, rev 3.1, june 2011 7 electrical characteristics test conditions dcvdd=1.8v, dbvdd=3.3v, avdd=3.3v, t a = +25 o c, 1khz signal, fs = 48khz, 24-bit audio data unless otherwise stated. parameter symbol test conditions min typ max unit microphone input pga inputs (micn, micp) inppgavol and pgaboost = 0db full-scale input signal level ? single- ended input via lin/rin 1 avdd/3.3 v rms full-scale input signal level ? pseudo-differential input 1,2 avdd*0.7/ 3.3 v rms input pga equivalent input noise inppgavol = +35.25db no input signal 0 to 20khz 76.5 db micn input resistance inppgavol = +35.25db 2 k micn input resistance inppgavol = 0db 58.5 k micn input resistance inppgavol = -12db 97.5 k micp input resistance all gain settings 124.5 k input capacitance all analogue input pins 10 pf maximum input pga programmable gain gain adjusted by inppgavol +33.25 +35.25 +37.25 db minimum input pga programmable gain gain adjusted by inppgavol -14.00 -12 -10.00 db programmable gain step size guaranteed monotonic 0.75 db input pga mute attenuation inppgamute 92 db input gain boost pgaboost= 0 0 db input gain boost pgaboost = 1 +20 db auxiliary analogue input (aux) full-scale input signal level 2 avdd/3.3 v rms input resistance input boost and mixer enabled, at 0db gain 20 k input capacitance all analogue inputs 10 pf maximum gain from aux input pga mixers gain adjusted by aux2boostvol +4.00 +6 +7.50 db minimum gain from aux input pga mixers gain adjusted by aux2boostvol -14.00 -12 -9.00 db aux2boostvol step size guaranteed monotonic 3 db analogue to digital converter (adc) - input from micn and micp in differential configuration to input pga inppgavo, pgaboost and adcvol = 0db signal to noise ratio 3 snr a-weighted avdd=3.3v 81 91 db total harmonic distortion 4 thd -1dbv input avdd=3.3v -83 -74 db total harmonic distortion + noise 5 thd+n -1dbv input avdd=3.3v -77 -68 db microphone bias bias voltage mbvsel=0 0.85* avdd 0.9*avdd 0.95* avdd v mbvsel=1 0.65*avdd v bias current source for v micbias within +/-3% 3 ma output noise voltage 1khz to 20khz 15 nv/ hz
WM8952 pre production w pp, rev 3.1, june 2011 8 test conditions dcvdd=1.8v, dbvdd=3.3v, avdd=3.3v, t a = +25 o c, 1khz signal, fs = 48khz, 24-bit audio data unless otherwise stated. parameter symbol test conditions min typ max unit digital input / output input high level v ih 0.7 dbvdd dbvdd+0.7 v input low level v il gnd-0.7 0.3 dbvdd v output high level v oh i ol =1ma 0.9 dbvdd dbvdd v output low level v ol i oh -1m a gnd 0.1xdbvdd v input capacitance all digital pins 10 pf input leakage all digital pins except mode -900 +900 na mode pin -90 +90 a terminology 1. full-scale input levels scale in relation to avdd depending upon the input or output used. for example, when avdd = 3.3v, 0dbfs = 1v rms (0dbv). when avdd < 3.3v the absolute level of 0dbfs will decrease with a linear relationship to avdd. 2. input level to rip and lip in differential configurations is limited to a maximum of -3db or performance will be reduced. 3. signal-to-noise ratio (db) ? snr is the difference in level between a reference full scale output signal and the device output with no signal applied. this ratio is also called idle channel noise. (no auto-zero or automute function is employed in achieving these results). 4. thd is the difference in level between a reference output signal and the first seven harmonics of the output signal. to calculate the ratio, the fundamental frequency of the output signal is notched out and an rms value of the next seven harmonics is calculated. 5. total harmonic distortion plus noise (db) ? thd+n is the difference in level between a reference output signal and the sum of the harmonics, wide-band noise and interference on the output signal. to calculate the ratio, the fundamental frequency of the output signal is notched out and an rms value of the total harmonics, wide-band noise and interference is calculated.
pre production WM8952 w pp, rev 3.1, june 2011 9 audio paths overview
WM8952 pre production w pp, rev 3.1, june 2011 10 power consumption typical current consumption for various scenarios is shown below. mode avdd (3v3) ma dvdd (1.8v) ma total power (mw) power off (no clocks) 0.038 0 0.125 sleep (vmid maintained, no clocks) 0.190 0 0.627 mono record (mic input, +20db gain, 8khz, quiescent) slave 4.1 0.3 14.2 mono record (mic input, +20db gain, 44.1khz, pll, quiescent) master 5.3 2.1 21.1 table 1 power consumption
pre production WM8952 w pp, rev 3.1, june 2011 11 signal timing requirements system clock timing mclk t mclkl t mclkh t mclky figure 1 system clock timing requirements test conditions dvdd=1.8v, avdd=3.3v, dgnd=agnd=0v, t a = +25 o c parameter symbol conditions min typ max unit system clock timing information mclk cycle time t mclky mclk=sysclk (=256fs) 81.38 ns mclk input to pll note 1 20 ns mclk duty cycle t mclkds 60:40 40:60 note 1: pll pre-scaling and pll n and k values should be set appropriately so that sysclk is no greater t han 12.288mhz. audio interface timing ? master mode figure 2 digital audio data timing ? master mode (see control interface)
WM8952 pre production w pp, rev 3.1, june 2011 12 test conditions dvdd=1.8v, avdd= 3.3v, dgnd=agnd =0v, t a =+25 o c, slave mode, fs=48khz, mclk=256fs, 24-bit data, unless otherwise stated. parameter symbol min typ max unit audio data input timing information frame propagation delay from bclk falling edge t dl 10 ns adcdat propagation delay from bclk falling edge t dda 15 ns audio interface timing ? slave mode figure 3 digital audio data timing ? slave mode test conditions dvdd=1.8v, avdd=3.3v, dgnd=agnd =0v, t a =+25 o c, slave mode, fs=48khz, mclk= 256fs, 24-bit data, unless otherwise stated. parameter symbol min typ max unit audio data input timing information bclk cycle time t bcy 81.38 ns bclk pulse width high t bch 32.55 ns bclk pulse width low t bcl 32.55 ns frame set-up time to bclk rising edge t lrsu 10 ns frame hold time from bclk rising edge t lrh 10 ns adcdat propagation delay from bclk falling edge t dd 15 ns note: bclk period should always be greater than or equal to mclk period.
pre production WM8952 w pp, rev 3.1, june 2011 13 control interface timing ? 3-wire mode figure 4 control interface timing ? 3-wire serial control mode test conditions dvdd = 1.8v, avdd = 3.3v, dgnd = agnd = 0v, t a = +25 o c, slave mode, fs = 48khz, mclk = 256fs, 24-bit data, unless otherwise stated. parameter symbol min typ max unit program register input information sclk rising edge to csb rising edge t scs 80 ns sclk pulse cycle time t scy 200 ns sclk pulse width low t scl 80 ns sclk pulse width high t sch 80 ns sdin to sclk set-up time t dsu 40 ns sclk to sdin hold time t dho 40 ns csb pulse width low t csl 40 ns csb pulse width high t csh 40 ns csb rising to sclk rising t css 40 ns pulse width of spikes that will be suppressed t ps 0 5 ns
WM8952 pre production w pp, rev 3.1, june 2011 14 control interface timing ? 2-wire mode sdin sclk t 3 t 1 t 6 t 2 t 7 t 5 t 4 t 3 t 8 t 9 figure 5 control interface timing ? 2-wire serial control mode test conditions dvdd=1.8v, avdd=3.3v, dgnd=agnd=0v, t a = +25 o c, slave mode, fs = 48khz, mclk = 256fs, 24-bit data, unless otherwise stated. parameter symbol min typ max unit program register input information sclk frequency 0 526 khz sclk low pulse-width t 1 1.3 us sclk high pulse-width t 2 600 ns hold time (start condition) t 3 600 ns setup time (start condition) t 4 600 ns data setup time t 5 100 ns sdin, sclk rise time t 6 300 ns sdin, sclk fall time t 7 300 ns setup time (stop condition) t 8 600 ns data hold time t 9 900 ns pulse width of spikes that will be suppressed t ps 0 5 ns
pre production WM8952 w pp, rev 3.1, june 2011 15 device description introduction features the WM8952 is a low power audio adc, with flexible line and microphone input. it offers great flexibility in use, and so can support many different modes of operation as follows: microphone inputs two microphone inputs are provided, allowing for either a differential microphone input or a single ended microphone to be connected. these inputs have a user programmable gain range of -12db to +35.25db using internal resistors. after the input pga stage comes a boost stage which can add a further 20db of gain. a microphone bias is output from the chip which can be used to bias the microphones. the signal routing can be configured to allow manual adjustment of mic levels, or to allow the alc loop to control the level of mic signal that is transmitted. total gain through the microphone paths of up to +55.25db can be selected. pga and alc operation a programmable gain amplifier is provided in the input path to the adc. this may be used manually or in conjunction with a mixed analogue/digital automatic level control (alc) which keeps the recording volume constant. aux input the device includes a mono input, aux, which can also be mixed into the signal path in a flexible fashion, either to the input pga as a second microphone input or as a line input. the configuration of this circuit, with integrated on-chip resistors allows several analogue signals to be summed into the single aux input if required. adc the mono adc uses a multi-bit high-order oversampling architecture to deliver optimum performance with low power consumption. various sample rates are supported, from the 8ks/s rate typically used in voice dictation, up to the 48ks/s rate used in high quality audio applications. digital filtering advanced sigma delta converters are used along with digital decimation and interpolation filters to give high quality audio at sample rates from 8ks/s to 48ks/s. application specific digital filters are also available which help to reduce the effect of specific noise sources such as wind noise or narrowband noise from other parts of the system. the filters incl ude a programmable adc high pass filter and four fully programmable adc notch filters. audio interfaces the WM8952 has a standard audio interface, to support the transmission of audio data to and from the chip. this interface is a 4 wire standard audio interface which supports a number of audio data formats including i 2 s, dsp mode, msb-first, left justified and msb-first, right justified, and can operate in master or slave modes. control interfaces to allow full software control over all its features, the WM8952 supports 2 or 3 wire control interface. it is fully compatible and an ideal partner for a wide range of industry standard microprocessors, controllers and dsps. the selection between 2-wire mode and 3-wire mode is determined by the state of the mode / gpio pin. if mode / gpio is high then 3-wire control mode is selected, if mode is low then 2-wire control mode is selected. in 2 wire mode, only slave operation is supported, and the address of the device is fixed as 0011010. clocking schemes WM8952 supports the normal audio clocking scheme operation, where 256fs mclk is provided to the adc. however, a pll is also included which may be used to generate the internal master clock frequency in the event that this is not available from the system controller. this pll uses an input clock, typically the 12mhz usb or ilink clock, to generate high quality audio clocks. if this pll is not required for generation of these clocks, it can be reconfigured to generate alternative clo cks which
WM8952 pre production w pp, rev 3.1, june 2011 16 may then be output on the gpio pin and used elsewhere in the system. power control the design of the WM8952 has given much attention to power consumption without compromising performance. it operates at low supply voltages, and includes the facility to power off any unused parts of the circuitry under software control. as a power saving measure, adc logic in the dsp core is held in its last enabled state when the adc is disabled. in order to prevent pops and clicks on restart due to residual data in the filters, the master clock must remain for at least 64 input samples after the adc has been disabled. input signal path the WM8952 has 3 flexible analogue inputs: two microphone inputs, and an auxiliary input. these inputs can be used in a variety of ways. the input signal path before the adc has a flexible pga block which then feeds into a gain boost/mixer stage. microphone inputs the WM8952 can accommodate a variety of microphone configurations including single ended and differential inputs. the inputs through the micn, micp and optionally aux pins are amplified through the input pga as shown in figure 6 . a pseudo differential input is the preferential configuration where the positive terminal of the input pga is connected to the micp input pin by setting micp2inppga=1. the microphone ground should then be connected to micn (when micn2inppga=1) or optionally to aux (when aux2inppga=1) input pins. alternatively a single ended microphone can be connected to the micn input with micn2inppga set to 1. the non-inverting terminal of the input pga should be connected internally to vmid by setting micp2inppga to 0. in pseudo-differential mode the larger signal should be input to micp and the smaller (e.g. noisy ground connections) should be input to micn. figure 6 microphone input pga circuit (switch positions shown are for differential mic input)
pre production WM8952 w pp, rev 3.1, june 2011 17 register address bit label default description r44 input control 2 aux2inppga 0 select aux amplifier output as input pga signal source. 0=aux not connected to input pga 1=aux connected to input pga amplifier negative terminal. 1 micn2inppga 1 connect micn to input pga negative terminal. 0=micn not connected to input pga 1=micn connected to input pga amplifier negative terminal. 0 micp2inppga 0 connect input pga amplifier positive terminal to micp or vmid. 0 = input pga amplifier positive terminal connected to vmid 1 = input pga amplifier positive terminal connected to micp through variable resistor string table 2 input control the input pga is enabled by the ippgaen register bit. register address bit label default description r2 power management 2 2 inppgaen 0 input microphone pga enable 0 = disabled 1 = enabled table 3 input pga enable control input pga volume control the input microphone pga has a gain range from -12db to +35.25db in 0.75db steps. the gain from the micn input to the pga output and from the aux amplifier to the pga output are always common and controlled by the register bits inppgavol[5:0]. these register bits also affect the micp pin when micp2inppga=1. when the automatic level control (alc) is enabled the input pga gain is then controlled automatically and the inppgavol bits should not be used.
WM8952 pre production w pp, rev 3.1, june 2011 18 register address bit label default description r45 input pga volume control 7 inppgazc 0 input pga zero cross enable: 0=update gain when gain register changes 1=update gain on 1 st zero cross after gain register write. 6 inppgamute 1 mute control for input pga: 0=input pga not muted, normal operation 1=input pga muted (and disconnected from the following input boost stage). 5:0 inppgavol 010000 input pga volume 000000 = -12db 000001 = -11.25db . 010000 = 0db . 111111 = 35.25db r32 alc control 1 8 alcsel 0 alc function select: 0=alc off (pga gain set by inppgavol register bits) 1=alc on (alc controls pga gain) table 4 input pga volume control auxiliary input an auxiliary input circuit (figure 7) is provided which consists of an amplifier which can be configured either as an inverting buffer for a single input signal or as a mixer/summer for multiple inputs with the use of external resistors. the circuit is enabled by the register bit auxen. figure 7 auxiliary input circuit the auxmode register bit controls the auxiliary input mode of operation: in buffer mode (auxmode=0) the switch labelled auxsw in figure 7 is open and the signal at the aux pin will be buffered and inverted through the aux circuit using only the internal components. in mixer mode (auxmode=1) the on-chip input resistor is bypassed, this allows the user to sum in multiple inputs with the use of external resistors. when used in this mode there will be gain variations through this path from part to part due to the variation of the internal 20k ? resistors relative to the higher tolerance external resistors. register address bit label default description r1 power management 1 6 auxen 0 auxiliary input buffer enable 0 = off 1 = on r44 input control 3 auxmode 0 0 = inverting buffer 1 = mixer (on-chip input resistor bypassed) table 5 auxiliary input buffer control
pre production WM8952 w pp, rev 3.1, june 2011 19 input boost the input boost circuit has 3 selectable inputs: the input microphone pga output, the aux amplifier output and the micp input pin (when not using a differential microphone configuration). these three inputs can be mixed together and have individual gain boost/adjust as shown in figure 8. figure 8 input boost stage the input pga path can have a +20db boost (pgaboost=1) a 0db pass through (pgaboost=0) or be completely isolated from the input boost circuit (inppgamute=1). register address bit label defaul t description r45 input pga gain control 6 inppgamute 1 mute control for input pga: 0=input pga not muted, normal operation 1=input pga muted (and disconnected from the following input boost stage). r47 input boost control 8 pgaboost 0 0 = pga output has +0db gain through input boost stage. 1 = pga output has +20db gain through input boost stage. table 6 input boost stage control the auxiliary amplifier path to the boost stage is controlled by the aux2boostvol[2:0] register bits. when aux2boostvol=000 this path is completely disconnected from the boost stage. settings 001 through to 111 control the gain in 3db steps from -12db to +6db. the micp path to the boost stage is controlled by the micp2boostvol[2:0] register bits. when micp2boostvol=000 this input pin is completely disconnected from the boost stage. settings 001 through to 111 control the gain in 3db steps from -12db to +6db.
WM8952 pre production w pp, rev 3.1, june 2011 20 register address bit label defaul t description r47 input boost control 6:4 micp2boostvol 000 controls the micp pin to the input boost stage (nb, when using this path set micp2inppga=0): 000=path disabled (disconnected) 001=-12db gain through boost stage 010=-9db gain through boost stage ? 111=+6db gain through boost stage 2:0 aux2boostvol 000 controls the auxiliary amplifier to the input boost stage: 000=path disabled (disconnected) 001=-12db gain through boost stage 010=-9db gain through boost stage ? 111=+6db gain through boost stage table 7 input boost stage control the boost stage is enabled under control of the boosten register bit. register address bit label default description r2 power management 2 4 boosten 0 input boost enable 0 = boost stage off 1 = boost stage on table 8 input boost enable control microphone biasing circuit the micbias output provides a low noise reference voltage suitable for biasing electret type microphones and the associated external resistor biasing network. refer to the applications information section for recommended external components. the micbias voltage can be altered via the mbvsel register bit. w hen m bvsel=0, micbias=0.9*avdd and when m bvsel=1, micbias=0.65*avdd. the output can be enabled or disabled using the micben control bit. register address bit label default description r1 power management 1 4 micben 0 microphone bias enable 0 = off (high impedance output) 1 = on table 9 microphone bias enable register address bit label default description r44 input control 8 mbvsel 0 microphone bias voltage control 0 = 0.9 * avdd 1 = 0.65 * avdd table 10 microphone bias voltage control
pre production WM8952 w pp, rev 3.1, june 2011 21 the internal micbias circuitry is shown in figure 9. note that the maximum source current capability for micbias is 3ma. the external biasing resistors therefore must be large enough to limit the micbias current to 3ma. figure 9 microphone bias schematic agnd mbvsel=0 micbias = 1.8 x vmid = 0.9 x avdd vmid internal resisto r internal resisto r mb mbvsel=1 micbias = 1.3 x vmid = 0.65 x avdd
WM8952 pre production w pp, rev 3.1, june 2011 22 analogue to digital converter (adc) the WM8952 uses a multi-bit, oversampled sigma-delta adc channel. the use of multi-bit feedback and high oversampling rates reduces the effects of jitter and high frequency noise. the adc full scale input level is proportional to avdd. with a 3.3v supply voltage, the full scale level is 1.0v rms . any voltage greater than full scale may overload the adc and cause distortion. adc digital filters the adc filters perform true 24 bit signal processing to convert the raw multi-bit oversampled data from the adc to the correct sampling frequency to be output on the digital audio interface. the digital filter path is illustrated in figure 10. figure 10 adc digital filter path the adc is enabled by the adcen register bit. register address bit label default description r2 power management 2 0 adcen 0 0 = adc disabled 1 = adc enabled table 11 adc enable the polarity of the output signal can also be changed under software control using the adcpol register bit. register address bit label default description r14 adc control 0 adcpol 0 0=normal 1=inverted table 12 adc polarity
pre production WM8952 w pp, rev 3.1, june 2011 23 selectable high pass filter a selectable high pass filter is provided. to disable this filter set hpfen=0. the filter has two modes controlled by hpfapp. in audio mode (hpfapp=0) the filter is first order, with a cut-off frequency of 3.7hz. in application mode (hpfapp=1) the filter is second order, with a cut-off frequency selectable via the hpfcut register. the cut-off frequencies when hpf app=1 are shown in table 14. register address bit label default description r14 adc control 8 hpfen 1 high pass filter enable 0=disabled 1=enabled 7 hpfapp 0 select audio mode or application mode 0=audio mode (1 st order, fc = ~3.7hz) 1=application mode (2 nd order, fc = hpfcut) 6:4 hpfcut 000 application mode cut-off frequency see table 14 for details. table 13 adc filter select hpfcut fs (khz) sr=101/100 sr=011/010 sr=001/000 8 11.02 5 12 16 22.0 5 24 32 44.1 48 000 82 113 122 82 113 122 82 113 122 001 102 141 153 102 141 153 102 141 153 010 131 180 196 131 180 196 131 180 196 011 163 225 245 163 225 245 163 225 245 100 204 281 306 204 281 306 204 281 306 101 261 360 392 261 360 392 261 360 392 110 327 450 490 327 450 490 327 450 490 111 408 563 612 408 563 612 408 563 612 table 14 high pass filter cut-off frequencies (hpfapp=1) note that the high pass filter values (when hpfapp=1) work on the basis that the sr register bits are set correctly for the actual sample rate as shown in table 14.
WM8952 pre production w pp, rev 3.1, june 2011 24 programmable notch filters four programmable notch filters are provided. these filters have a programmable centre frequency and bandwidth, programmable via two coefficients, a0 and a1. a0 and a1 are represented by the register bits nfx_a0[13:0] and nfx_a1[13:0]. the notch filter coefficients should be converted to sign / magnitude notation to enter into the registers. notch filter 3 can also be programmed as a 1 st order low pass filter. because these coefficient values require two register writes to set up there is an nfx_up (notch filter update) flag for each filter which should be set only when both a0 and a1 for the filter have been set. the notch filters can be individually enabled, using the corresponding nfx_en register bit, as can be seen in figure 11: figure 11 labelling of notch filters and arrangement of notch filter enables the notch filter coefficients must be entered using a sign / magnitude notation. register address bit label default description r16 notch filter 0a 15 nf0_up 0 notch filter 0 update. the notch filter 0 values used internally only update when one of the nf0_up bits is set high. 14 nf0_en 0 notch filter 0 enable: 0=disabled 1=enabled 13:0 nf0_a0 0 notch filter 0 a0 coefficient r17 notch filter 0b 15 nf0_up 0 notch filter 0 update. the notch filter 0 values used internally only update when one of the nf0_up bits is set high. 13:0 nf0_a1 0 notch filter 0 a1 coefficient table 15 notch filter 0 function
pre production WM8952 w pp, rev 3.1, june 2011 25 register address bit label default description r18 notch filter 1a 15 nf1_up 0 notch filter 1 update. the notch filter 1 values used internally only update when one of the nfu bits is set high. 14 nf1_en 0 notch filter 1 enable. 0=disabled 1=enabled 13:0 nf1_a0 0 notch filter 1 a0 coefficient r19 notch filter 1b 15 nf1_up 0 notch filter 1 update. the notch filter 1 values used internally only update when one of the nfu bits is set high. 13:0 nf1_a1 0 notch filter 1 a1 coefficient table 16 notch filter 1 function register address bit label default description r20 notch filter 2a 15 nf2_up 0 notch filter 2 update. the notch filter 2 values used internally only update when one of the nfu bits is set high. 14 nf2_en 0 notch filter 2 enable. 0=disabled 1=enabled 13:0 nf2_a0 0 notch filter 2 a0 coefficient r21 notch filter 2b 15 nf2_up 0 notch filter 2 update. the notch filter 2 values used internally only update when one of the nfu bits is set high. 13:0 nf2_a1 0 notch filter 2 a1 coefficient table 17 notch filter 2 function register address bit label default description r22 notch filter 3a 15 nf3_up 0 notch filter 3 update. the notch filter 3 values used internally only update when one of the nfu bits is set high. 14 nf3_en 0 notch filter 3 enable. 0=disabled 1=enabled 13:0 nf3_a0 0 notch filter 3 a0 coefficient r23 notch filter 3b 15 nf3_up 0 notch filter 3 update. the notch filter 3 values used internally only update when one of the nfu bits is set high. 14 nf3_lp 0 notch filter 3 mode select 0 = notch filter mode 1 = low pass filter mode 13:0 nf3_a1 0 notch filter 3 a1 coefficient table 18 notch filter 3 function the notch filter coefficients must be entered using a sign / magnitude notation. the msb of the 14-bit register word (nfx_ax[13]) is reserved for the sign part, leaving the 13 remaining bits for the magnitude part.
WM8952 pre production w pp, rev 3.1, june 2011 26 the notch filter coefficients are calculated as follows: ) 2 / w tan( 1 ) 2 / w tan( 1 a b b 0 + ? = where: s c 0 f / f 2 w = s b b f / f 2 w = f c = centre frequency in hz, f b = -3db bandwidth in hz, f s = sample frequency in hz the actual register values can be determined from the coefficients as follows: nfn_a0 = -a0 x 2 13 nfn_a1 = -a1 x 2 12 these values are then converted to a 14-bit sign / magnitude notation. to configure notch filter 3 as a 1 st order low pass filter, set the nf3_lp bit to 1 and calculate the coefficients as follows: 0 a 0 = 1 ) 2 / w tan( 1 ) 2 / w tan( a c c 1 + ? = where: s c c f / f 2 w = f c = cut-off frequency in hz, f s = sample frequency in hz the actual register values can be determined from the coefficients as follows: nf3_a0 = 0 nf3_a1 = -a 1 x2 12 these values are then converted to a 14-bit sign / magnitude notation. digital adc volume control the output of the adcs can be digitally attenuated over a range from ?127db to 0db in 0.5db steps. the gain for a given eight-bit code x is given by: gain = 0.5 x (x?255) db for 1 x 255, mute for x = 0 register address bit label default description r15 adc digital volume 7:0 adcvol [7:0] 11111111 ( 0db ) adc digital volume control 0000 0000 = digital mute 0000 0001 = -127db 0000 0010 = -126.5db ... 0.5db steps up to 1111 1111 = 0db table 19 adc volume
pre production WM8952 w pp, rev 3.1, june 2011 27 input limiter / automatic level control (alc) the WM8952 has an automatic pga gain control circuit, which can function as an input peak limiter or as an automatic level control (alc). the automatic level control (alc) provides continuous adjustment of the input pga in response to the amplitude of the input signal. a digital peak detector monitors the input signal amplitude and compares it to a register defined threshold level (alclvl). if the signal is below the threshold, the alc will increase the gain of the pga at a rate set by alcdcy. if the signal is above the threshold, the alc will reduce the gain of the pga at a rate set by alcatk. the alc has two modes selected by the alcmode register: normal mode and peak limiter mode. the alc/limiter function is enabled by setting the register bit r32[8] alcsel. register address bit label default description r32 (20h) alc control 1 2:0 alcmin [2:0] 000 (-12db) set minimum gain of pga 000 = -12db 001 = -6db 010 = 0db 011 = +6db 100 = +12db 101 = +18db 110 = +24db 111 = +30db 5:3 alcmax [2:0] 111 (+35.25db) set maximum gain of pga 111 = +35.25db 110 = +29.25db 101 = +23.25db 100 = +17.25db 011 = +11.25db 010 = +5.25db 001 = -0.75db 000 = -6.75db 8 alcsel 00 alc function select 0 = alc disabled 1 = alc enabled r33 (21h) alc control 2 3:0 alclvl [3:0] 1011 (-6db) alc target ? sets signal level at adc input 1111 = -1.5dbfs 1110 = -1.5dbfs 1101 = -3dbfs 1100 = -4.5dbfs 1011 = -6dbfs 1010 = -7.5dbfs 1001 = -9dbfs 1000 = -10.5dbfs 0111 = -12dbfs 0110 = -13.5dbfs 0101 = -15dbfs 0100 = -16.5dbfs 0011 = -18dbfs 0010 = -19.5dbfs 0001 = -21dbfs 0000 = -22.5dbfs
WM8952 pre production w pp, rev 3.1, june 2011 28 register address bit label default description 7:4 alchld [3:0] 0000 (0ms) alc hold time before gain is increased. 0000 = 0ms 0001 = 2.67ms 0010 = 5.33ms 0011 = 10.66ms 0100 = 21.32ms 0101 = 42.64ms 0110 = 85.28ms 0111 = 0.17s 1000 = 0.34s 1001 = 0.68s 1010 or higher = 1.36s r34 (22h) alc control 3 8 alcmode 0 determines the alc mode of operation: 0 = alc mode (normal operation) 1 = limiter mode. 7:4 alcdcy [3:0] 0011 (26ms/6db) decay (gain ramp-up) time (alcmode ==0) per step per 6db 90% of range 0000 410us 3.38ms 23.6ms 0001 820us 6.56ms 47.2ms 0010 1.64ms 13.1ms 94.5ms ? (time doubles with every step) 1010 or higher 420ms 3.36s 24.2s 0011 (5.8ms/6db) decay (gain ramp-up) time (alcmode ==1) per step per 6db 90% of range 0000 90.8us 726us 5.23ms 0001 182us 1.45ms 10.5ms 0010 363us 2.91ms 20.9ms ? (time doubles with every step) 1010 93ms 744ms 5.36s 3:0 alcatk [3:0] 0010 (3.3ms/6db) alc attack (gain ramp-down) time (alcmode == 0) per step per 6db 90% of range 0000 104us 832us 6ms 0001 208us 1.66ms 12ms 0010 416us 3.33ms 24ms ? (time doubles with every step) 1010 or higher 106ms 852ms 6.13s 0010 (726us/6db) alc attack (gain ramp-down) time (alcmode == 1) per step per 6db 90% of range 0000 22.7us 182.4us 1.31ms 0001 45.4us 363us 2.62ms 0010 90.8us 726us 5.23ms ? (time doubles with every step) 1010 or higher 23.2ms 186ms 1.34s
pre production WM8952 w pp, rev 3.1, june 2011 29 register address bit label default description r42 (2ah) alc control 4 1 alczc 0 (zero cross off) alc uses zero cross detection circuit. 0 = disabled (recommended) 1 = enabled table 20 alc control registers when the alc is disabled, the input pga remains at the last controlled value of the alc. an input gain update must be made by writing to the inppgavoll/r register bits. if there is no analogue input signal present when the alc is enabled, the alc may not function correctly. to ensure correct operation of the alc with no analogue input signal, the input pga volume control register (r45) should be written with the inppgamute and alczc bits set to 0 before setting the alcsel bit to 1 in register r32 (bit 8). normal mode in normal mode, the alc will attempt to maintain a constant signal level by increasing or decreasing the gain of the pga. the following diagram shows an example of this. figure 12 alc normal mode operation
WM8952 pre production w pp, rev 3.1, june 2011 30 limiter mode in limiter mode, the alc will reduce peaks that go above the threshold level, but will not increase the pga gain beyond the starting level. the starting level is the pga gain setting when the alc is enabled in limiter mode. if the alc is started in limiter mode, this is the gain setting of the pga at start-up. if the alc is switched into limiter mode after running in alc mode, the starting gain will be the gain at switchover. the diagram below shows an example of limiter mode. figure 13 alc limiter mode operation attack and decay times the attack and decay times set the update times for the pga gain. the attack time is the time constant used when the gain is reducing. the decay time is the time constant used when the gain is increasing. in limiter mode, the time constants are faster than in alc mode. the time constants are shown below in terms of a single gain step, a change of 6db and a change of 90% of the pgas gain range. note that, these times will vary slightly depending on the sample rate used (specified by the sr register).
pre production WM8952 w pp, rev 3.1, june 2011 31 normal mode alcmode = 0 (normal mode) alcatk t atk t atk6db t atk90% 0000 104 s 832 s6ms 0001 208 s 1.66ms 12ms 0010 416 s 3.33ms 24ms 0011 832 s 6.66ms 48ms 0100 1.66ms 13.3ms 96ms 0101 3.33ms 26.6ms 192ms 0110 6.66ms 53.2ms 384ms 0111 13.3ms 106ms 767ms 1000 26.6ms 213.2ms 1.53s 1001 53.2ms 426ms 3.07s 1010 106ms 852ms 6.13s attack time (s) alcmode = 0 (normal mode) alcdcy t dcy t dcy6db t dcy90% 0000 410 s 3.28ms 23.6ms 0001 820 s 6.56ms 47.2ms 0010 1.64ms 13.1ms 94.5ms 0011 3.28ms 26.2ms 189ms 0100 6.56ms 52.5ms 378ms 0101 13.1ms 105ms 756ms 0110 26.2ms 210ms 1.51s 0111 52.5ms 420ms 3.02s 1000 105ms 840ms 6.05s 1001 210ms 1.68s 12.1s 1010 420ms 3.36s 24.2s decay time (s) table 21 alc normal mode (attack and decay times)
WM8952 pre production w pp, rev 3.1, june 2011 32 limiter mode alcmode = 1 (limiter mode) alcatk t atklim t atklim6db t atklim90% 0000 22.7 s 182 s1.31ms 0001 45.4 s 363 s2.62ms 0010 90.8 s 726 s5.23ms 0011 182 s 1.45ms 10.5ms 0100 363 s 2.91ms 20.9ms 0101 726 s 5.81ms 41.8ms 0110 1.45ms 11.6ms 83.7ms 0111 2.9ms 23.2ms 167ms 1000 5.81ms 46.5ms 335ms 1001 11.6ms 93ms 669ms 1010 23.2ms 186ms 1.34s attack time (s) alcmode = 1 (limiter mode) alcdcy t dcylim t dcylim6db t dcylim90% 0000 90.8 s 726 s5.23ms 0001 182 s 1.45ms 10.5ms 0010 363 s 2.91ms 20.9ms 0011 726 s 5.81ms 41.8ms 0100 1.45ms 11.6ms 83.7ms 0101 2.91ms 23.2ms 167ms 0110 5.81ms 46.5ms 335ms 0111 11.6ms 93ms 669ms 1000 23.2ms 186ms 1.34s 1001 46.5ms 372ms 2.68s 1010 93ms 744ms 5.36s attack time (s) table 22 alc limiter mode (attack and decay times)
pre production WM8952 w pp, rev 3.1, june 2011 33 minimum and maximum gain the alcmin and alcmax register bits set the minimum/maximum gain value that the pga can be set to whilst under the control of the alc. this has no effect on the pga when alc is not enabled. register address bit label default description r32 alc control 1 5:3 alcmax 111 set maximum gain of pga 2:0 alcmin 000 set minimum gain of pga table 23 alc max/min gain in normal mode, alcmax sets the maximum boost which can be applied to the signal. in limiter mode, alcmax will normally have no effect (assuming the starting gain value is less than the maximum gain specified by alcmax) because the maximum gain is set at the starting gain level. alcmin sets the minimum gain value which can be applied to the signal. figure 14 alc min/max gain alcmax maximum gain (db) 111 35.25 110 29.25 101 23.25 100 17.25 011 11.25 010 5.25 001 -0.75 000 -6.75 table 24 alc max gain values
WM8952 pre production w pp, rev 3.1, june 2011 34 alcmin minimum gain (db) 000 -12 001 -6 010 0 011 6 100 12 101 18 110 24 111 30 table 25 alc min gain values note that if the alc gain setting strays outside the alc operating range, either by starting the alc outside of the range or changing the alcmax or alcmin settings during operation, the alc will immediately adjust the gain to return to the alc operating range. it is recommended that the alc starting gain is set between the alcmax and alcmin limits. alc hold time (normal mode only) in normal mode, the alc has an adjustable hold time which sets a time delay before the alc begins its decay phase (gain increasing). the hold time is set by the alchld register. register address bit label default description r33 a lc control 2 7:4 alchld 0000 alc hold time before gain is increased. table 26 alc hold time if the hold time is exceeded this indicates that the signal has reached a new average level and the alc will increase the gain to adjust for that new average level. if the signal goes above the threshold during the hold period, the hold phase is abandoned and the alc returns to normal operation.
pre production WM8952 w pp, rev 3.1, june 2011 35 figure 15 alclvl
WM8952 pre production w pp, rev 3.1, june 2011 36 figure 16 alc hold time alchld t hold (s) 0000 0 0001 2.67ms 0010 5.34ms 0011 10.7ms 0100 21.4ms 0101 42.7ms 0110 85.4ms 0111 171ms 1000 342ms 1001 684ms 1010 1.37s table 27 alc hold time values
pre production WM8952 w pp, rev 3.1, june 2011 37 peak limiter to prevent clipping when a large signal occurs just after a period of quiet, the alc circuit includes a limiter function. if the adc input signal exceeds 87.5% of full scale (?1.16db), the pga gain is ramped down at the maximum attack rate (as when alcatk = 0000), until the signal level falls below 87.5% of full scale. this function is automatically enabled whenever the alc is enabled. note: if alcatk = 0000, then the limiter makes no difference to the operation of the alc. it is designed to prevent clipping when long attack times are used. noise gate (normal mode only) when the signal is very quiet and consists mainly of noise, the alc function may cause ?noise pumping?, i.e. loud hissing noise during silence periods. the WM8952 has a noise gate function that prevents noise pumping by comparing the signal level at the input pins against a noise gate threshold, ngth. the noise gate cuts in when: signal level at adc [dbfs] < ngth [dbfs] + pga gain [db] + mic boost gain [db] this is equivalent to: signal level at input pin [dbfs] < ngth [dbfs] the pga gain is then held constant (preventing it from ramping up as it normally would when the signal is quiet). the table below summarises the noise gate control register. the ngth control bits set the noise gate threshold with respect to the adc full-scale range. the threshold is adjusted in 6db steps. levels at the extremes of the range may cause inappropriate operation, so care should be taken with set?up of the function. the noise gate only operates in conjunction with the alc and cannot be used in limiter mode. register address bit label default description r35 (23h) alc noise gate control 2:0 ngth 000 noise gate threshold: 000 = -39db 001 = -45db 010 = -51db 011 = -57db 100 = -63db 101 = -69db 110 = -75db 111 = -81db 3 ngaten 0 noise gate function enable 1 = enable 0 = disable table 28 alc noise gate control
WM8952 pre production w pp, rev 3.1, june 2011 38 the diagrams below show the response of the system to the same signal with and without noise gate. figure 17 alc operation above noise gate threshold
pre production WM8952 w pp, rev 3.1, june 2011 39 figure 18 noise gate operation
WM8952 pre production w pp, rev 3.1, june 2011 40 digital audio interfaces the audio interface has 3 pins: ? adcdat: adc data output ? frame: data alignment clock ? bclk: bit clock, for synchronisation the clock signals bclk and frame can be outputs when the WM8952 operates as a master, or inputs when it is a slave (see master and slave mode operation, below). four different audio data formats are supported: ? left justified ? right justified ? i 2 s ? dsp mode a / b all of these modes are msb first. they are described in audio data formats, below. refer to the electrical characteristic section for timing information. master and slave mode operation the WM8952 audio interface may be configured as either master or slave. as a master interface device the WM8952 generates bclk and frame and thus controls sequencing of the data transfer on adcdat. to set the device to master mode register bit ms should be set high. in slave mode (ms=0), the WM8952 responds with data to clocks it receives over the digital audio interfaces. audio data formats in left justified mode, the msb is available on the first rising edge of bclk following an frame transition. the other bits up to the lsb are then transmitted in order. depending on word length, bclk frequency and sample rate, there may be unused bclk cycles before each frame transition. figure 19 left justified audio interface (assuming n-bit word length) in right justified mode, the lsb is available on the last rising edge of bclk before a frame transition. all other bits are transmitted before (msb first). depending on word length, bclk frequency and sample rate, there may be unused bclk cycles after each frame transition. figure 20 right justified audio interface (assuming n-bit word length)
pre production WM8952 w pp, rev 3.1, june 2011 41 in i 2 s mode, the msb is available on the second rising edge of bclk following a frame transition. the other bits up to the lsb are then transmitted in order. depending on word length, bclk frequency and sample rate, there may be unused bclk cycles between the lsb of one sample and the msb of the next. figure 21 i 2 s audio interface (assuming n-bit word length) in dsp/pcm mode, the left channel msb is available on either the 1 st (mode b) the 2 nd (mode a) rising edge of bclk (selectable by framep) following a rising edge of frame. right channel data immediately follows left channel data. depending on word length, bclk frequency and sample rate, there may be unused bclk cycles between the lsb of the right channel data and the next sample. framep should be set to 0 in this mode. figure 22 dsp/pcm mode audio interface (mode a, framep=0) figure 23 dsp/pcm mode audio interface (mode b, framep=1)
WM8952 pre production w pp, rev 3.1, june 2011 42 audio interface control the register bits controlling audio format, word length and master / slave mode are summarised below. register bit ms selects audio interface operation in master or slave mode. in master mode bclk, and frame are outputs. the frequency of bclk and frame in master mode are controlled with bclkdiv. these are divided down versions of master clock. this may result in short bclk pulses at the end of a frame if there is a non-integer ratio of bclks to frame clocks. register address bit label default description r4 audio interface control 9 loutr 0 loutr control 0=normal 1=input mono channel data output on both left and right channels 8 bcp 0 bclk polarity 0=normal 1=inverted 7 framep 0 frame clock polarity (for rj, lj and i 2 s formats) 0=normal 1=inverted dsp mode control 1 = configures interface so that msb is available on 1st bclk rising edge after frame rising edge 0 = configures interface so that msb is available on 2nd bclk rising edge after frame rising edge 6:5 wl 10 word length 00 = 16 bits 01 = 20 bits 10 = 24 bits 11 = 32 bits (see note) 4:3 fmt 10 audio interface data format select: 00=right justified 01=left justified 10=i 2 s format 11= dsp/pcm mode 1 alrswap 0 controls whether adc data appears in ?right? or ?left? phases of frame clock: 0=adc data appear in ?left? phase of frame 1=adc data appears in ?right? phase of frame r5 companding control 5 wl8 0 8 bit word length enable only recommended for use with companding 0=word length controlled by wl 1=8 bits table 29 audio interface control note: right justified mode will only operate with a maximum of 24 bits. if 32-bit mode is selected the device will operate in 24-bit mode.
pre production WM8952 w pp, rev 3.1, june 2011 43 register address bit label default description r6 clock generation control 8 clksel 1 controls the source of the clock for all internal operation: 0=mclk 1=pll output 7:5 mclkdiv 010 sets the scaling for either the mclk or pll clock output (under control of clksel) 000=divide by 1 001=divide by 1.5 010=divide by 2 011=divide by 3 100=divide by 4 101=divide by 6 110=divide by 8 111=divide by 12 4:2 bclkdiv 000 configures the bclk and frame output frequency, for use when the chip is master over bclk. 000=divide by 1 (bclk=mclk) 001=divide by 2 (bclk=mclk/2) 010=divide by 4 011=divide by 8 100=divide by 16 101=divide by 32 110=reserved 111=reserved 0 ms 0 sets the chip to be master over frame and bclk 0=bclk and frame clock are inputs 1=bclk and frame clock are outputs generated by the WM8952 (master) table 30 clock control audio sample rates the WM8952 sample rates are set using the sr register bits. the cut-offs for the digital filters and the alc attack/decay times stated are determined using these values and assume a 256fs master clock rate. if a sample rate that is not explicitly supported by the sr register settings is required then the closest sr value to that sample rate should be chosen, the filter characteristics and the alc attack, decay and hold times will scale appropriately. register address bit label default description r7 additional control 3:1 sr 000 approximate sample rate (configures the coefficients for the internal digital filters): 000=48khz 001=32khz 010=24khz 011=16khz 100=12khz 101=8khz 110-111=reserved table 31 sample rate control
WM8952 pre production w pp, rev 3.1, june 2011 44 master clock and phase locked loop (pll) the WM8952 has an on-chip phase-locked loop (pll) circuit that can be used to: ? generate master clocks for the WM8952 audio functions from another external clock, e.g. in telecoms applications. ? generate an output clock, on gpio, for another part of the system (derived from an existing audio master clock). table 32 shows the pll and internal clocking arrangement on the WM8952. the pll is enabled or disabled by the pllen register bit. note : in order to minimise current consumption, the pll is disabled when the vmidsel[1:0] bits are set to 00b. vmidsel[1:0] must be set to a value other than 00b to enable the pll. register address bit label default description r1 power management 1 5 pllen 0 pll enable 0=pll off 1=pll on table 32 pllen control bit figure 24 pll and clock select circuit
pre production WM8952 w pp, rev 3.1, june 2011 45 the pll frequency ratio r = f 2 /f 1 (see table 33) can be set using the register bits pllk and plln: n = int r k = int (2 24 (r - n)) n controls the ratio of the division, and k the fractional part. the pll output then passes through a fixed divide by 4, and can also be further divided by mclkdiv[3:0] (see figure 24). the divided clock (sysclk) can be used to clock the WM8952 dsp core. register address bit label default description r36 pll n value 7 pll_powerdown 0 pll power 0=on 1=off 6 fracen 1 fractional divide within the pll 0=disabled (lower power) 1=enabled 5:4 pllprescale 00 00 = mclk input multiplied by 2 (default) 01 = mclk input not divided 10 = divide mclk by 2 before input to pll 11 = divide mclk by 4 before input to pll 3:0 plln 1000 integer (n) part of pll input/output frequency ratio. use values greater than 5 and less than 13. r37 pll k value 1 5:0 pllk [23:18] 0ch fractional (k) part of pll1 input/output frequency ratio (treat as one 24-digit binary number). r38 pll k value 2 8:0 pllk [17:9] 093h r39 pll k value 3 8:0 pllk [8:0] 0e9h table 33 pll frequency ratio control integer n division the integer division ratio (n) is determined by n[3:0] and must be in the range 5 to 12 . if the pll frequency is an exact integer (5,6,7,8,9,10,11,12) then frac_en can be set to 0 for low power operation. input clock (f 1 ) desired pll output (f 2 ) division required (r) fractional division (k) integer division (n) sdm 11.2896mhz 90.3168mhz 8 0 8 0 12.2880mhz 98.3040mhz 8 0 8 0 table 34 pll modes of operation (integer n mode) fractional k mode the fractional k bits provides k[23:0] provide finer divide resolution for the pll frequency ratio (up to 1/2 24 ). if these are used then frac_en must be set. the relationship between the required division x, the fractional division k[23:0] and the integer division n[3:0] is: k = 2 24 ( r ? n) where 0 < (r ? n) < 1 and k is rounded to the nearest whole number.
WM8952 pre production w pp, rev 3.1, june 2011 46 example: pll input clock (f 1 ) is 12mhz and the required clock (sysclk) is 12.288mhz. r should be chosen to ensure 5 < n < 13. there is a fixed divide by 4 in the pll and a selectable divider (mclkdiv[3:0]) after the pll which should be set to divide by 2 to meet this requirement. enabling the divide by 2 sets the required f 2 = 4 * 2 * 12.288mhz = 98.304mhz. r = 98.304 / 12 = 8.192 n = int r = 8 k = int (2 24 x (8.192 ? 8)) = 3221225 = 3126e9h so n[3:0] will be 8h and k[23:0] will be 3126e9h to produce the desired 98.304mhz clock. the pll performs best when f 2 is around 90mhz. its stability peaks at n=8. some example settings are shown in table 35. mclk (mhz) desired output (mhz) f2 (mhz) prescale divide postscale divide (mclkdiv) r n (hex) k (hex) 12 11.2896 90.3168 1 2 7.5264 7 86c226 12 12.2880 98.3040 1 2 8.192 8 3126e9 13 11.2896 90.3168 1 2 6.947446 6 f28bd4 13 12.2880 98.3040 1 2 7.561846 7 8fd525 14.4 11.2896 90.3168 1 2 6.272 6 45a1ca 14.4 12.2880 98.3040 1 2 6.826667 6 d3a06e 19.2 11.2896 90.3168 2 2 9.408 9 6872b0 19.2 12.2880 98.3040 2 2 10.24 a 3d70a3 19.68 11.2896 90.3168 2 2 9.178537 9 2db492 19.68 12.2880 98.3040 2 2 9.990243 9 fd809f 19.8 11.2896 90.3168 2 2 9.122909 9 1f76f8 19.8 12.2880 98.3040 2 2 9.929697 9 ee009e 24 11.2896 90.3168 2 2 7.5264 7 86c226 24 12.2880 98.3040 2 2 8.192 8 3126e9 26 11.2896 90.3168 2 2 6.947446 6 f28bd4 26 12.2880 98.3040 2 2 7.561846 7 8fd525 27 11.2896 90.3168 2 2 6.690133 6 boac93 27 12.2880 98.3040 2 2 7.281778 7 482296 table 35 pll frequency examples
pre production WM8952 w pp, rev 3.1, june 2011 47 companding the WM8952 supports a-law and -law companding. this can be enabled by writing the appropriate value to the adc_comp register bit. if packed mode companding is desired the wl8 register bit is available. it will override the normal audio interface wl bits to give an 8-bit word length. refer to table 29 audio interface control for setting the output word length. register address bit label default description r5 companding control 2:1 adc_comp 0 adc companding 00=off 01=reserved 10= -law 11=a-law table 36 companding control companding involves using a piecewise linear approximation of the following equations (as set out by itu-t g.711 standard) for data compression: -law (where =255 for the u.s. and japan): f(x) = ln( 1 + |x|) / ln( 1 + ) -1 x 1 a-law (where a=87.6 for europe): f(x) = a|x| / ( 1 + lna) } for x 1/a f(x) = ( 1 + lna|x|) / (1 + lna) } for 1/a x 1 the companded data is also inverted as recommended by the g.711 standard (all 8 bits are inverted for -law, all even data bits are inverted for a-law). the data will be transmitted as the first 8 msb?s of data. companding converts 13 bits ( -law) or 12 bits (a-law) to 8 bits using non-linear quantization. the input data range is separated into 8 levels, allowing low amplitude signals better precision than that of high amplitude signals. this is to exploit the operation of the human auditory system, where louder sounds do not require as much resolution as quieter sounds. the companded signal is an 8- bit word containing sign (1-bit), exponent (3-bits) and mantissa (4-bits). bit7 bit[6:4] bit[3:0] sign exponent mantissa table 37 8-bit companded word composition u-law companding 0 20 40 60 80 100 120 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 normalised input companded output 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 normalised output figure 25 u-law companding
WM8952 pre production w pp, rev 3.1, june 2011 48 a-law companding 0 20 40 60 80 100 120 0 0.2 0.4 0.6 0.8 1 normalised input companded output 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 normalised output figure 26 a-law companding
pre production WM8952 w pp, rev 3.1, june 2011 49 general purpose input/output in 2-wire mode, the csb pin is not required and it can be used as a gpio pin. in the WM8952, a separate gpio pin is available and this can be used for gpio in 3-wire mode. also in 3 wire mode, the mode / gpio can be configured as a gpio by setting the mode_gpio register bit whichever pin is used for gpio, it is controlled from the gpio control register r8. the gpiosel bits allow the chosen pin to be configured to perform a variety of useful tasks as shown in table 38 note that slowclken must be enabled when using the jack detect function. register address bit label default description r8 gpio control 5:4 opclkdiv 00 pll output clock division ratio 00=divide by 1 01=divide by 2 10=divide by 3 11=divide by 4 3 gpiopol 0 gpio polarity invert 0=non inverted 1=inverted 2:0 gpiosel 000 gpio function select: 000=gpio off 010=temp ok 100= sysclk clock o/p 101=pll lock all other values: reserved table 38 gpio control control interface selection of control mode and 2-wire mode address the control interface can operate as either a 3-wire or 2-wire interface. the mode / gpio pin determines the 2 or 3 wire mode as shown in table 39. the WM8952 is controlled by writing to registers through a serial control interface. a control word consists of 24 bits. the first 7 bits (b23 to b16) are address bits that select which control register is accessed. the remaining 16 bits (b15 to b0) are register bits, corresponding to the 16 bits in each control register. mode / gpio interface format low 2 wire hi-z 3 wire high 3 wire table 39 control interface mode selection use of mode as a gpio pin in 3-wire mode in 3-wire mode, mode can be used as a gpio pin. if mode is being used as a gpio output, the partner device doesn?t have to drive mode - the pin will be pulled-up internally causing 3-wire mode will be selected. the gpio function is enabled by setting the mode_gpio register bit. the mode pin can then be controlled using the gpio register bits as described in figure 27. to use mode as a gpio input, mode must be undriven or driven high at start-up. specifically mode must be high or hi-z during an initial write to the control interface which sets the mode_gpio register bit. after mode_gpio has been set, 3-wire mode selection is overridden internally and the mode pin can be used freely as a gpio input or output.
WM8952 pre production w pp, rev 3.1, june 2011 50 figure 27 example usage of mode pin to generate a clock out in 3-wire mode this example shows how the mode_gpio register bit interfaces to the mode pad in the case there mode is used as a gpio output. when mode_gpio is set, the internal version of mode is overridden to high and the mode pin output driver is enabled. the pull up, which is used to default 3-wire mode at start-up, is disabled as a power saving measure. mode_gpio cannot be set in 2- wire mode - this would prevent correct operation of the control interface. internal timing is arranged to ensure that the override is in place before the pull-up is disabled. register address bit label default description r8 gpio control 7 mode_gpio 0 selects mode pin as a gpio pin 0 = mode is an input. mode selects 2- wire mode when low and 3-wire mode when high. 1 = mode can be an input or output under the control of the gpio control register. interface operates in 3-wire mode regardless of what happens on the mode pin. table 40 mode is gpio control auto-incremental writes are supported in 2 wire and 3 wire modes. this is enabled by default. register address bit label default description r9 control interface 1 autoinc 1 auto-incremental write enable 0=auto-incremental writes disabled 1=auto-incremental writes enabled table 41 control interface
pre production WM8952 w pp, rev 3.1, june 2011 51 3-wire serial control mode in 3-wire mode, every rising edge of sclk clocks in one data bit from the sdin pin. a rising edge on csb/gpio latches in a complete control word consisting of the last 16 bits. figure 28 3-wire serial control interface readback in 3-wire mode the following two timing diagrams are also supported. figure 29 alternative 3-wire serial control timing figure 30 alternative 3-wire serial control timing a limited number of readback addresses are provided to enable alc operation to be monitored and to establish the identity and revision of the device. register address bit label default description r0 software reset 15:0 chip_id readback the chip id r1 power management 1 2:0 device_revi son readback the device_revison table 42 readback registers
WM8952 pre production w pp, rev 3.1, june 2011 52 2-wire serial control mode the WM8952 supports software control via a 2-wire serial bus. many devices can be controlled by the same bus, and each device has a unique 7-bit device address (this is not the same as the 7-bit address of each register in the WM8952). the WM8952 operates as a slave device only. the controller indicates the start of data transfer with a high to low transition on sdin while sclk remains high. this indicates that a device address and data will follow. all devices on the 2-wire bus respond to the start condition and shift in the next eight bits on sdin (7-bit address + read/write bit, msb first). if the device address received matches the address of the WM8952, then the WM8952 responds by pulling sdin low on the next clock pulse (ack). if the address is not recognised or the r/w bit is ?1? when operating in write only mode, the WM8952 returns to the idle condition and wait for a new start condition and valid address. during a write, once the WM8952 has acknowledged a correct address, the controller sends the first byte of control data (b15 to b8, i.e. the WM8952 register address plus the first bit of register data). the WM8952 then acknowledges the first data byte by pulling sdin low for one clock pulse. the controller then sends the second byte of control data (b7 to b0, i.e. the remaining 8 bits of register data), and the WM8952 acknowledges again by pulling sdin low. transfers are complete when there is a low to high transition on sdin while sclk is high. after a complete sequence the WM8952 returns to the idle state and waits for another start condition. if a start or stop condition is detected out of sequence at any point during data transfer (i.e. sdin changes while sclk is high), the device jumps to the idle condition. figure 31 2-wire serial control interface in 2-wire mode the WM8952 has a fixed device address, 0011010. resetting the chip the WM8952 can be reset by performing a write of any value to the software reset register (address 0 hex). this will cause all register values to be reset to their default values. in addition to this there is a power-on reset (por) circuit which ensures that the registers are set to default when the device is powered up. power supplies the WM8952 requires the following power supplies: avdd and agnd: analogue supply, powers all analogue functions. avdd can range from 2.5v to 3.6v and has the most significant impact on overall power consumption. a larger avdd slightly improves audio quality. dvdd: digital core supply, powers all digital functions except the audio and control interfaces. dvdd can range from 1.71v to 3.6v, and has no effect on audio quality. the return path for dvdd is dgnd. it is possible to use the same supply voltage for these. however, digital and analogue supplies should be routed and decoupled separately on the pcb to keep digital switching noise out of the analogue signal paths.
pre production WM8952 w pp, rev 3.1, june 2011 53 recommended power up/down seqence in order to minimise output pop and click noise, it is recommended that the WM8952 device is powered up and down using one of the following sequences: power up: 1. turn on external power supplies. wait for supply voltages to settle. 2. reset internal registers to default state (software reset). 3. enable non-vmid derived bias generator (vmid_op_en = 1) and level shifters (lvlshift_en = 1). 4. select clock source to mclk (clksel = 0) and audio mode (master or slave). 5. enable power on bias control (pob_ctrl = 1) and vmid soft start (soft_start = 1). 6. set vmidsel[1:0] bits for 50k ? reference string impedance. 7. wait for the vmid supply to settle. *note 2. 8. enable analogue amplifier bias control (bi asen = 1) and vmid buffer (bufioen = 1). *notes 1 and 2. 9. disable power on bias control (pob_ctrl = 0) and vmid soft start (soft_start = 0). power down: 1. enable non-vmid derived bias generator (vmid_op_en = 1). 2. enable on bias control (pob_ctrl = 1). 3. disable analogue amplifier bias control (biasen = 0) and vmid (vmidsel[1:0] bits set to off). 4. enable fast vmid discharge (toggle = 1) to discharge vmid capacitor. 5. wait for vmid capacitor to fully discharge. 6. reset all registers to their default state (software reset). 7. turn off external power supply voltages. notes: 1. this step enables the internal device bias buffer and the vmid buffer for unassigned inputs. this will provide a startup reference for all inputs. this will cause the inputs to ramp towards vmid in a way that is controlled and predictable. 2. choose the value of vmidsel bits based on the startup time (vmidsel = 10 for the slowest startup, vmidsel = 11 for the fastest startup). startup time is defined by the value of the vmidsel bits (the reference impedance) and the external decoupling capacitor on vmid. in addition to the power on sequence, it is recommended that the zero cross functions are used when changing the volume in the pgas to avoid any audible pops and clicks.
WM8952 pre production w pp, rev 3.1, june 2011 54 power management vmid the analogue circuitry will not work when vmid is disabled (vmidsel[1:0] = 00b). the impedance of the vmid resistor string, together with the decoupling capacitor on the vmid pin will determine the start-up time of the vmid circuit. register address bit label default description r1 power management 1 1:0 vmidsel 00 reference string impedance to vmid pin (determines startup time): 00=off (open circuit) 01=50k ? 10=250k ? 11=5k ? (for fastest startup) table 43 vmid impedance control biasen register address bit label default description r1 power management 1 3 biasen 0 analogue amplifier bias control 0=disabled 1=enabled table 44 biasen control estimated supply currents when either the adc is enabled it is estimated that approximately 4ma will be drawn from dvdd when fs=48khz (this will be lower at lower sample rates). when the pll is enabled an additional 700 microamps will be drawn from dvdd. table 45 shows the estimated 3.3v avdd current drawn by various circuits, by register bit. register bit avdd current (milliamps) pllen 1.4ma (with clocks applied) micben 0.5ma biasen 0.3ma bufioen 0.1ma vmidsel 5k=>0.3ma, less than 0.1ma for 50k/250k boosten 0.2ma inppgaen 0.2ma adcen 2.6ma table 45 avdd supply current
pre production WM8952 w pp, rev 3.1, june 2011 55 pop minimisation register soft_start is the enable bit for the vmid soft-start function. setting the bit to 1 causes charging of the vmid decoupling cap to follow a soft-start profile which minimises pops. this soft- start profile has minimal impact on vmid charge time. fast vmid discharge is enabled using toggle. setting to 1 opens a low impedance discharge path from vmid to gnd. this function can be used during power down to reduce the discharge time of the vmid decoupling cap. must be set to 0 for normal operation. register address bit label default description r7 additional control 5 soft_st art 0 vmid soft start 0=disabled 1=enabled 4 toggle 0 fast vmid discharge 0=normal 1=enable (used during power-down) table 46 pop minimisation control thermal shutdown to protect the WM8952 from overheating a thermal shutdown circuit is included. the thermal shutdown can be configured to produce an interrupt when the device reaches approximately 125 o c. see general purpose input/output section. register address bit label default description r49 output control 1 tsden 1 thermal shutdown enable 0 : thermal shutdown disabled 1 : thermal shutdown enabled table 47 thermal shutdown
WM8952 pre production w pp, rev 3.1, june 2011 56 register map dec hex 000 software reset 1000_1001_0100_0000 0 0000_0000_0000_0000 202 power management 200000000000boosten0inppgaen0adcen 0000_0000_0000_0000 303 power management 300000000 0 0000000 0000_0000_0000_0000 404 audio interface 0000000bcpframep 0 alrswap 0 0000_0000_0101_0000 505 companding control000000000 0 wl8 0 0 0 0000_0000_0000_0000 606 clock gen control0000000clksel 0ms 0000_0001_0100_0000 707 additional control0000000000soft_starttoggle slowclken 0000_0000_0000_0000 808 gpio stuff 00000000mode_gpio0 gpiopol 0000_0000_0000_0000 909 control interface 00000000000000autoinc0 0000_0000_0000_0010 10 0a reserved 11 0b reserved 0000000011111111 0000_0000_1111_1111 12 0c reserved 13 0d reserved 14 0e adc control 0000000hpfenhpfapp 0 00adcpol 0000_0001_0000_0000 15 0f adc digital vol 00000000 0000_0000_1111_1111 16 10 notch filter 1 nf0_up nf0_en 0000_0000_0000_0000 17 11 notch filter 2 nf0_up 0 0000_0000_0000_0000 18 12 notch filter 3 nf1_up nf1_en 0000_0000_0000_0000 19 13 notch filter 4 nf1_up 0 0000_0000_0000_0000 20 14 notch filter 5 nf2_up nf2_en 0000_0000_0000_0000 21 15 notch filter 6 nf2_up 0 0000_0000_0000_0000 22 16 notch filter 7 nf3_up nf3_en 0000_0000_0000_0000 23 17 notch filter 8 nf3_up nf3_lp 0000_0000_0000_0000 24 18 reserved 25 19 reserved 26 1a reserved 27 1b reserved 28 1c reserved 29 1d reserved 30 1e reserved 31 1f reserved 32 20 alc control 1 0alcsel0 0 0000_0000_0011_1000 33 21 alc control 2 00000000 0000_0000_0000_1011 34 22 alc control 3 0000000alcmode 0000_0000_0011_0010 35 23 noise gate 000000000000ngen 0000_0000_0000_0000 36 24 pll n 00000000 pll_powerdo wn fracen 0000_0000_0100_1000 37 25 pll k 1 0000000000 0000_0000_0000_1100 38 26 pll k 2 0000000 0000_0000_1001_0011 39 27 pll k 3 0000000 0000_0000_1110_1001 40 28 reserved 41 29 reserved 42 2a spare register 00000000000000alczc0 0000_0000_0011_0000 43 2b reserved 44 2c input ctrl 0000000micbvsel0000auxmode aux2inppga micn2inppga micp2inppga 0000_0000_0000_0010 45 2d inp pga gain ctrl00000000inppgazc inppgamute 0000_0000_0101_0000 46 2e reserved 47 2f adc boost ctrl0000000 pgaboost 00 0000_0000_0000_0000 48 30 reserved 49 31 thermal shutdown00000000000000tsden0 0000_0000_0000_0010 50 32 reserved 51 33 reserved 52 34 reserved 53 35 reserved 54 36 reserved 55 37 reserved 56 38 reserved b1 b0 default value (bin) b5 b4 b3 b2 b9 b8 b7 b6 b13b12b11b10 addr register name b15 b14 pllk[17:9] pllk[8:0] inppgavol[5:0] micp2boostvol[2:0] aux2boostvol[2:0] ngth[2:0] pll_prescale[1:0] plln[3:0] pllk[23:18] alchld[3:0] alclvl[3:0] alcdcy[3:0] alcatk[3:0] nf3_a1[13:0] alcgain[5:0] alcmax[2:0] alcmin[2:0] nf1_a1[13:0] nf2_a0[13:0] nf2_a1[13:0] nf3_a0[13:0] adcvol[7:0] nf0_a0[13:0] nf0_a1[13:0] nf1_a0[13:0] sr[2:0] opclkdiv[1:0] gpiosel[2:0] hpfcut[2:0] wl[1:0] fmt[1:0] adc_comp[1:0] mclkdiv[2:0] bclkdiv[2:0] pllen micben biasen vmidsel[1:0] device_revision[2:0] 0 0 lvlshift_en auxen sotware reset on write / chip id on read 101 power management 1 0 0 0 0 0 0 note: bits marked in green are readable. other bits are write-only.
pre production WM8952 w pp, rev 3.1, june 2011 57 register bits by address notes: 1. default values of n/a indicate non-latched data bits (e.g. software reset or volume update bits). 2. register bits marked as "reserved" should not be changed from the default. register address bit label default description refer to 0 (00h) [15:0] reset / chip_id n/a writing to this register will apply a software reset. reading from this register will return the device id resetting the chip / control interface 1 (01h) 15:8 000h reserved 7 lvlshift_en 0 enable bit for the level shifters. 1 for normal operation, 0 for standby. power management 6 auxen 0 auxilliary input buffer enable 0 = off 1 = on auxiliary inputs 5 pllen 0 pll enable 0=pll off 1=pll on master clock and phase locked loop (pll) 4 micben 0 microphone bias enable 0 = off (high impedance output) 1 = on microphone biasing circuit 3 biasen 0 anal ogue amplifier bias control 0=disabled 1=enabled power management 2:0 device_revi sion 000 readback from this register will return the device revision in this position control interface 2 bufioen 0 enable bit for the vmid buffer. the vmid buffer is used to maintain a buffered vmid voltage on all analogue input pins. 1. for normal operation 0. for standby (where inputs settle to gnd). enabling the outputs 1:0 vmidsel 00 reference string impedance to vmid pin: 00=off (open circuit) 01=50k ? 10=250k ? 11=5k ? power management 2 (02h) 15:5 000h reserved 4 boosten 0 input boost enable 0 = boost stage off 1 = boost stage on input boost 3 0 reserved 2 inppgaen 0 input microphone pga enable 0 = disabled 1 = enabled input signal path 1 0 reserved 0 adcen 0 adc enable control 0 = adc disabled 1 = adc enabled analogue to digital converter (adc) 3 (03h) 15:0 00h reserved 4 (04h) 15:9 0000000 reserved 8 bcp 0 bclk polarity 0=normal 1=inverted digital audio interfaces
WM8952 pre production w pp, rev 3.1, june 2011 58 register address bit label default description refer to 7 framep 0 frame clock polarity 0=normal 1=inverted digital audio interfaces dsp mode control 1 = configures the interface so that msb is available on 1 st bclk rising edge after frame rising edge 0 = configures the interface so that msb is available on 2 nd bclk rising edge after frame rising edge 6:5 wl 10 word length 00=16 bits 01=20 bits 10=24 bits 11=32 bits digital audio interfaces 4:3 fmt 10 audio interface data format select: 00=right justified 01=left justified 10=i 2 s format 11= dsp/pcm mode digital audio interfaces 2 0 reserved 1 alrswap 0 controls whether adc data appears in ?right? or ?left? phases of frame clock: 0=adc data appear in ?left? phase of frame 1=adc data appears in ?right? phase of frame digital audio interfaces 0 0 reserved 5 (05h) 15:6 000h reserved 5 wl8 0 8 bit word length for companding 0=word length controlled by wl 1=8 bits digital audio interfaces 4:3 reserved 2:1 adc_comp 00 adc companding 00=off 01=reserved 10= -law 11=a-law digital audio interfaces 0 reserved 6 (06h) 15:9 00h reserved 8 clksel 1 controls the source of the clock for all internal operation: 0=mclk 1=pll output digital audio interfaces 7:5 mclkdiv 010 sets the scaling for either the mclk or pll clock output (under control of clksel) 000=divide by 1 001=divide by 1.5 010=divide by 2 011=divide by 3 100=divide by 4 101=divide by 6 110=divide by 8 111=divide by 12 digital audio interfaces
pre production WM8952 w pp, rev 3.1, june 2011 59 register address bit label default description refer to 4:2 bclkdiv 000 configures the bclk and frame output frequency, for use when the chip is master over bclk. 000=divide by 1 (bclk=mclk) 001=divide by 2 (bclk=mclk/2) 010=divide by 4 011=divide by 8 100=divide by 16 101=divide by 32 110=reserved 111=reserved digital audio interfaces 1 0 reserved 0 ms 0 sets the chip to be master over frame and bclk 0=bclk and frame clock are inputs 1=bclk and frame clock are outputs generated by the WM8952 (master) digital audio interfaces 7 (07h) 15:6 00000 reserved 6 reserved 5 soft_start 0 vmid soft start 0=disabled 1=enabled pop minimisation 4 toggle 0 fast vmid discharge 0=normal 1=enable (used during power-down) pop minimisation 3:1 sr 000 approximate sample rate (configures the coefficients for the internal digital filters): 000=48khz 001=32khz 010=24khz 011=16khz 100=12khz 101=8khz 110-111=reserved audio sample rates 0 slowclken 0 enables the timeout clock for zero cross detection. zero cross timeout 8 (08h) 15:8 00h reserved 7 mode_gpio 0 selects mode as a gpio pin 0 = mode is an input. mode selects 2-wire mode when low and 3-wire mode when high. 1 = mode can be an input or output under the control of the gpio control register. interface operates in 3- wire mode regardless of when happens on the mode pin. control interface 6 0 reserved 5:4 opclkdiv 00 pll output clock division ratio 00=divide by 1 01=divide by 2 10=divide by 3 11=divide by 4 general purpose input output 3 gpiopol 0 gpio polarity invert 0=non inverted 1=inverted general purpose input output
WM8952 pre production w pp, rev 3.1, june 2011 60 register address bit label default description refer to 2:0 gpiosel 000 gpio function select: 000=gpio off 010=temp ok 100=sysclk clock o/p 101=pll lock all other values: reserved general purpose input output 9 (09h) 15:2 reserved 1 autoinc 1 auto-incremental write enable 0=auto-incremental writes disabled 1=auto-incremental writes enabled control interface 0 0 reserved 10 (0ah) 15:0 0000h reserved 11 (0bh) 15:0 00ffh reserved 12 (0ch) 15:0 reserved 13 (0dh) 15:0 reserved 14 (0eh) 15:9 00h reserved 8 hpfen 1 high pass filter enable 0=disabled 1=enabled analogue to digital converter (adc) 7 hpfapp 0 select audio mode or application mode 0=audio mode (1 st order, fc = ~3.7hz) 1=application mode (2 nd order, fc = hpfcut) analogue to digital converter (adc) 6:4 hpfcut 000 application mode cut-off frequency see table 14 for details. analogue to digital converter (adc) 3:1 00 reserved 0 adcpol 0 adc polarity 0=normal 1=inverted analogue to digital converter (adc) 15 (0fh) 15:8 00h reserved 7:0 adcvol 11111111 adc digital volume control 0000 0000 = digital mute 0000 0001 = -127db 0000 0010 = -126.5db ... 0.5db steps up to 1111 1111 = 0db analogue to digital converter (adc) 16 (10h) 15 nf0_up 0 notch filter 0 update. the notch filter 0 values used internally only update when one of the nf0_up bits is set high. analogue to digital converter (adc) 14 nf0_en 0 notch filter 0 enable: 0=disabled 1=enabled analogue to digital converter (adc) 13:0 nf0_a0 0000h notch filter 0 a0 coefficient analogue to digital converter (adc) 17 (11h) 15 nf0_up 0 notch filter 0 update. the notch filter 0 values used internally only update when one of the nf0_up bits is set high. analogue to digital converter (adc) 14 0 reserved 13:0 nf0_a1 0000h notch filter 0 a1 coefficient analogue to digital converter (adc) 18 (12h) 15 nf1_up 0 notch filter 1 update. the notch filter 1 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc)
pre production WM8952 w pp, rev 3.1, june 2011 61 register address bit label default description refer to 14 nf1_en 0 notch filter 1 enable. 0=disabled 1=enabled analogue to digital converter (adc) 13:0 nf1_a0 0000h notch filter 1 a0 coefficient analogue to digital converter (adc) 19 (13h) 15 nf1_up 0 notch filter 1 update. the notch filter 1 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc) 14 0 reserved 13:0 nf1_a1 0000h notch filter 1 a1 coefficient analogue to digital converter (adc) 20 (14h) 15 nf2_up 0 notch filter 2 update. the notch filter 2 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc) 14 nf2_en 0 notch filter 2 enable. 0=disabled 1=enabled analogue to digital converter (adc) 13:0 nf2_a0 0000h notch filter 2 a0 coefficient analogue to digital converter (adc) 21 (15h) 15 nf2_up 0 notch filter 2 update. the notch filter 2 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc) 14 0 reserved 13:0 nf2_a1 0000h notch filter 2 a1 coefficient analogue to digital converter (adc) 22 (16h) 15 nf3_up 0 notch filter 3 update. the notch filter 3 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc) 14 nf3_en 0 notch filter 3 enable 0=disabled 1=enabled analogue to digital converter (adc) 13:0 nf3_a0 0000h notch filter 3 a0 coefficient analogue to digital converter (adc) 23 (17h) 15 nf3_up 0 notch filter 3 update. the notch filter 3 values used internally only update when one of the nfu bits is set high. analogue to digital converter (adc) 14 nf3_lp 0 notch filter 3 mode select 0 = notch filter mode 1 = low pass filter mode analogue to digital converter (adc) 13:0 nf3_a1 0000h notch filter 3 a1 coefficient analogue to digital converter (adc) 24 (18h) 15:0 0032h reserved 25 (19h) 15:0 0000h reserved 26 (1ah) 15:0 0000h reserved 27 (1bh) 15:0 0000h reserved 28 (1ch) 15:0 0000h reserved 29 (1dh) 15:0 0000h reserved 30 (1eh) 15:0 0000h reserved 31(1fh) 15:0 0000h reserved
WM8952 pre production w pp, rev 3.1, june 2011 62 register address bit label default description refer to 32 (20h) 15:10 alcgain[5:0] 000000 readback from this register will return the alc gain in this position input limiter / automatic level control (alc) 9 0 reserved 8 alcsel 0 alc function select 0=alc disabled 1=alc enabled input limiter / automatic level control (alc) 7:6 00 reserved 5:3 alcmax 111 set maximum gain of pga input limiter / automatic level control (alc) 2:0 alcmin 000 set minimum gain of pga input limiter / automatic level control (alc) 33 (21h) 15:8 000h reserved 7:4 alchld 000 alc hold time before gain is increased. input limiter / automatic level control (alc) 3:0 alclvl 1011 alc threshold level. sets the desired signal level. input limiter / automatic level control (alc) 34 (22h) 15:9 00h reserved 8 alcmode 0 determines the alc mode of operation: 0=normal mode 1=limiter mode. input limiter / automatic level control (alc) 7:4 alcdcy 0011 decay (gain ramp-up) time input limiter / automatic level control (alc) 3:0 alcatk 0010 alc attack (gain ramp-down) time input limiter / automatic level control (alc) 35 (23h) 15:4 000h reserved 3 ngen 0 noise gate function enable 1 = enable 0 = disable input limiter / automatic level control (alc) 2:0 ngth 000 noise gate threshold input limiter / automatic level control (alc) 36 (24h) 15:8 00h reserved 7 pll_powerd own 0 pll power 0=on 1=off master clock and phase locked loop (pll) 6 fracen 1 fractional divide within the pll 0=disabled (lower power) 1=enabled master clock and phase locked loop (pll) 5:4 pllprescale 00 00 = mclk input multiplied by 2 (default) 01 = mclk input not divided 10 = divide mclk by 2 before input to pll 11 = divide mclk by 4 before input to pll master clock and phase locked loop (pll) 3:0 plln[3:0] 1100 integer (n) part of pll input/output frequency ratio. use values greater than 5 and less than 13. master clock and phase locked loop (pll) 37 (25h) 15:6 000h reserved 5:0 pllk[23:18] 001100 fractional (k) part of pll1 input/output frequency ratio (treat as one 24-digit binary number). master clock and phase locked loop (pll) 38 (26h) 15:9 00h reserved
pre production WM8952 w pp, rev 3.1, june 2011 63 register address bit label default description refer to 8:0 pllk[17:9] 010010011 fractional (k) part of pll1 input/output frequency ratio (treat as one 24-digit binary number). master clock and phase locked loop (pll) 39 (27h) 15:9 00h reserved 8:0 pllk[8:0] 011101001 fractional (k) part of pll1 input/output frequency ratio (treat as one 24-digit binary number). master clock and phase locked loop (pll) 40 (28h) 15:0 0000h reserved 41 (29h) 15:0 0000h reserved 42 (2ah) 15:2 0 reserved alc control 4 1 alczc 0 (zero cross off) alc uses zero cross detection circuit. 0 = disabled (recommended) 1 = enabled 0 0 reserved 43 (2bh) 15:0 0000h reserved 44 (2ch) 15:9 00h reserved 8 mbvsel 0 micr ophone bias voltage control 0 = 0.9 * avdd 1 = 0.75 * avdd input signal path 7:4 0h reserved 3 auxmode 0 auxiliary input mode 0 = inverting buffer 1 = mixer (on-chip input resistor bypassed) input signal path 2 aux2inppga 0 select aux amplifier output as input pga signal source. 0=aux not connected to input pga 1=aux connected to input pga amplifier negative terminal. input signal path 1 micn2inppga 1 connect micn to input pga negative terminal. 0=micn not connected to input pga 1=micn connected to input pga amplifier negative terminal. input signal path 0 micp2inppga 0 connect input pga amplifier positive terminal to micp or vmid. 0 = input pga amplifier positive terminal connected to vmid 1 = input pga amplifier positive terminal connected to micp through variable resistor string input signal path 45 (2dh) 15:8 00h reserved 7 inppgazc 0 input pga zero cross enable: 0=update gain when gain register changes 1=update gain on 1 st zero cross after gain register write. input signal path 6 inppgamute 1 mute control for input pga: 0=input pga not muted, normal operation 1=input pga muted (and disconnected from the following input boost stage). input signal path 5:0 inppgavol 010000 input pga volume 000000 = -12db 000001 = -11.25db . 010000 = 0db . 111111 = 35.25db input signal path 46 (2eh) 15:0 0000h reserved
WM8952 pre production w pp, rev 3.1, june 2011 64 register address bit label default description refer to 47 (2fh) 15:9 00h reserved 8 pgaboost 0 input boost 0 = pga output has +0db gain through input boost stage. 1 = pga output has +20db gain through input boost stage. input signal path 7 0 reserved 6:4 micp2boostvo l 000 controls the micp pin to the input boost stage (nb, when using this path set micp2inppga=0): 000=path disabled (disconnected) 001=-12db gain through boost stage 010=-9db gain through boost stage ? 111=+6db gain through boost stage input signal path 3 0 reserved 2:0 aux2boostvol 000 controls the auxiliary amplifier to the input boost stage: 000=path disabled (disconnected) 001=-12db gain through boost stage 010=-9db gain through boost stage ? 111=+6db gain through boost stage input signal path 48 (30h) 15:0 0000h reserved 49 (31h) 15:2 000h reserved 1 tsden 1 thermal shutdown enable 0 : thermal shutdown disabled 1 : thermal shutdown enabled output switch 0 vroi 0 vref (avdd/2 or 1.5xavdd/2) to analogue output resistance 0: approx 1k 1: approx 30 k analogue outputs 50 (32h) 15:0 0000h reserved 51 (33h) 15:0 0000h reserved 52 (34h) 15:0 0000h reserved 53 (35h) 15:0 0000h reserved 54 (36h) 15:9 0079h reserved 55 (37h) 15:0 0000h reserved 56 (38h) 15:8 0000h reserved
pre production WM8952 w pp, rev 3.1, june 2011 65 digital filter characteristics parameter test conditions min typ max unit adc filter passband +/- 0.025db 0 0.454fs -6db 0.5fs passband ripple +/- 0.025 db stopband 0.546fs stopband attenuation f > 0.546fs -60 db group delay 21/fs adc high pass filter high pass filter corner frequency -3db 3.7 hz -0.5db 10.4 -0.1db 21.6 table 48 digital filter characteristics terminology 1. stop band attenuation (db) ? the degree to which the frequency spectrum is attenuated (outside audio band) 2. pass-band ripple ? any variation of the frequency response in the pass-band region 3. note that this delay applies only to the filters and does not include additional delays through other digital circuits. see table 49 for the total delay. parameter min typ max unit total delay (adc analogue input to digital audio interface output) 28/fs 30/fs 32/fs fs table 49 total group delay notes 1. wind noise filter is disabled. adc filter responses -120 -100 -80 -60 -40 -20 0 0 0.5 1 1.5 2 2.5 3 frequency (fs) response (db) -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0 0.1 0.2 0.3 0.4 0.5 frequency (fs) response (db) figure 32 adc digital filter frequency response figure 33 adc digital filter ripple
WM8952 pre production w pp, rev 3.1, june 2011 66 highpass filter the WM8952 has a selectable digital high pass filter in the adc filter path. this filter has two modes, audio and applications. in audio mode the filter is a 1 st order iir with a cut-off of around 3.7hz. in applications mode the filter is a 2 nd order high pass filter with a selectable cut-off frequency. -40 -35 -30 -25 -20 -15 -10 -5 0 5 0 5 10 15 20 25 30 35 40 45 frequency (hz) response (db) -60 -50 -40 -30 -20 -10 0 10 0 200 400 600 800 1000 1200 frequency (hz) response (db) figure 34 adc high pass filter response, hpfapp=0 figure 35 adc high pass filter responses (48khz), hpfapp=1, all cut-off settings shown. -80 -70 -60 -50 -40 -30 -20 -10 0 10 0 200 400 600 800 1000 1200 frequency (hz) response (db) -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 0 200 400 600 800 1000 1200 frequency (hz) response (db) figure 36 adc high pass filter responses (24khz), hpfapp=1, all cut-off settings shown. figure 37 adc high pass filter responses (12khz), hpfapp=1, all cut-off settings shown.
pre production WM8952 w pp, rev 3.1, june 2011 67 notch filters and low pass filter the WM8952 supports four programmable notch filters. the fourth notch filter can be configured as a low pass filter. the following illustrates three digital notch filters, followed by a single low pass filter in the adc filter path. both the centre frequency and -3db bandwidth are programmable for the notch filters. the cut off frequency is programmable for the low pass filter. the following graphs show the responses of 1) a single notch filter at three chosen centre frequencies, with three bandwidths for each, 2) the low pass filter at three chosen cut off frequencies and 3) the cascade of three notch filters followed by the low pass filter, each with a different centre / cut off frequency with three bandwidths for each. figure 38 adc notch filter responses (48khz); fc=100hz, 1khz, 10khz; fb = 100hz, 600hz, 2khz figure 39 adc low pass filter responses (48khz); fc= 1khz, 5khz, 10khz -60 +0 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 r e s p o n s e (db) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) -60 +0 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 r e s p o n s e (db) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz ) t t
WM8952 pre production w pp, rev 3.1, june 2011 68 figure 40 cumulative notch + low pass filters responses ( 48khz); nf0 fc = 1khz; nf1 fc = 5khz; nf2 fc = 10khz; lpf fc = 11khz; fb = 100hz, 600hz, 2khz notch filter worked example the following example illustrates how to calculate the a0 and a1 coefficients for a desired centre frequency and -3db bandwidth. f c = 1000 hz f b = 100 hz f s = 48000 hz s c 0 f / f 2 w = = 2 x (1000 / 48000) = 0.1308996939 rads s b b f / f 2 w = = 2 x (100 / 48000) = 0.01308996939 rads ) 2 / w tan( 1 ) 2 / w tan( 1 a b b 0 + ? = = ) 2 / 9 0130899693 . 0 tan( 1 ) 2 / 9 0130899693 . 0 tan( 1 + ? = 0.9869949627 ) w cos( ) a 1 ( a 0 0 1 + ? = = ) 1308996939 . 0 cos( ) 9869949627 . 0 1 ( + ? = -1.969995945 nfn_a0 = -a0 x 2 13 = -8085 (rounded to nearest whole number) nfn_a1 = -a1 x 2 12 = 8069 (rounded to nearest whole number) these values are then converted to a 14-bit sign / magnitude notation: nfn_a0[13] = 1; nfn_a0[12:0] = 13?h1f95; nfn_a0 = 14?h3f95 = 14?b11111110010101 nfn_a1[13] = 0; nfn_a1[12:0] = 13?h1f85; nfn_a1 = 14?h1f85 = 14?b01111110000101 -40 +0 -35 -30 -25 -20 -15 -10 -5 r e s p o n s e (db) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) t t t
pre production WM8952 w pp, rev 3.1, june 2011 69 recommended external components figure 41 recommended external components
WM8952 pre production w pp, rev 3.1, june 2011 70 package diagram dm054.a b: 28 ball w-csp package 2.590 x 2.500 x 0.7mm body, 0.40 mm ball pitch a1 corner top view e z 0.10 2 x d 5 4 detail 2 detail 2 a a2 2 z 0.10 2 x a1 z bbb z 1 e1 a d1 detail 1 d c b f e e e bottom view 1 65432 6 g notes: 1. primary datum -z- and seating plane are defined by the spherical crowns of the solder balls. 2. this dimension includes stand-off height ?a1? and backside coating. 3. a1 corner is identified by ink/laser mark on top package. 4. bilateral tolerance zone is applied to each side of the package body. 5. ?e? represents the basic solder ball grid pitch. 6. this drawing is subject to change without notice. 7. follows jedec design guide mo-211-c. a1 0.195 d d1 e e1 e 2.000 bsc 2.500 bsc 0.275 2.000 bsc 0.400 bsc 2.590 bsc dimensions (mm) symbols min nom max note a 0.7 a2 0.385 0.410 0.435 5 f1 0.785 0.615 0.220 0.245 g 0.070 0.035 0.105 h 0.260 bsc f2 0.230 f1 f2 h
pre production WM8952 w pp, rev 3.1, june 2011 71 important notice wolfson microelectronics plc (?wolfson?) products and services are sold subject to wolfson?s terms and conditions of sale, delivery and payment supplied at the time of order acknowledgement. wolfson warrants performance of its products to the specifications in effect at the date of shipment. wolfson reserves the right to make changes to its products and specifications or to discontinue any product or service without notice. customers should therefore obtain the latest version of relevant information from wolfson to verify that the information is current. testing and other quality control techniques are utilised to the extent wolfson deems necessary to support its warranty. specific testing of all parameters of each device is not necessarily performed unless required by law or regulation. in order to minimise risks associated with customer applications, the customer must use adequate design and operating safeguards to minimise inherent or procedural hazards. wolfson is not liable for applications assistance or customer product design. the customer is solely responsible for its selection and use of wolfson products. wolfson is not liable for such selection or use nor for use of any circuitry other than circuitry entirely embodied in a wolfson product. wolfson?s products are not intended for use in life support systems, appliances, nuclear systems or systems where malfunction can reasonably be expected to result in personal injury, death or severe property or environmental damage. any use of products by the customer for such purposes is at the customer?s own risk. wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other intellectual property right of wolfson covering or relating to any combination, machine, or process in which its products or services might be or are used. any provision or publication of any third party?s products or services does not constitute wolfson?s approval, licence, warranty or endorsement thereof. any third party trade marks contained in this document belong to the respective third party owner. reproduction of information from wolfson datasheets is permissible only if reproduction is without alteration and is accompanied by all associated copyright, proprietary and other notices (including this notice) and conditions. wolfson is not liable for any unauthorised alteration of such information or for any reliance placed thereon. any representations made, warranties given, and/or liabilities accepted by any person which differ from those contained in this datasheet or in wolfson?s standard terms and conditions of sale, delivery and payment are made, given and/or accepted at that person?s own risk. wolfson is not liable for any such representations, warranties or liabilities or for any reliance pl aced thereon by any person. address wolfson microelectronics plc westfield house 26 westfield road edinburgh eh11 2qb united kingdom tel :: +44 (0)131 272 7000 fax :: +44 (0)131 272 7001 email :: sales@wolfsonmicro.com
WM8952 pre production w pp, rev 3.1, june 2011 72 revision history date rev originator changes 01/12/08 3.0 bdc changed to pre production status 25/04/11 3.1 jmacd ts removed qfn package option and references in datasheet. changed reel qty to 3,500 devices

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