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pam8902a document number: dsxxxxx rev. 1 - 3 1 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated 30 v pp mono class-d audio amplifier for piezo/ceramic speakers with anti-saturation description the pam8902a is a mono, class-d audio amplifier with integrated boost convertor designed for piez o and ceramic speakers. the pam8902a is capable for driving a ceramic/piezo speaker with 30v pp (0.6vrms) from a 3.6v power supply. the pam8902a's boost converter operates at a fixed fr equency of 1.5mhz and provides a 17.5v supply with a minimum number of external components. the three gain mode of 18db, 22db and 26db is easy for using. pam unique ant i -saturat ion technology which detects output signal clip due to the over level input signal suppress the output signal clip automatically. pam8902a features an integrated audio low pass filter that rejects high frequency noise, thus improving audio fidelity. pam8902a also provides thermal, over current, under and over voltage protection. the pam8902a is available in a 16-ball 1.95mm x 1.95mm csp package and 16-pin qfn4x4 package. features ? supply voltage range from 2.7v to 5.5v package. ? 30v pp output load voltage from a 2.7v supply ? integrated boost converter generates 17.5v supply ? programmable soft-start ? unique anti-saturation function ? small boost converter inductor ? selectable gain of 18db, 22db, and 26db (refer to ?application notes?) ? selectable boost output voltage of 8v, 12v, and 17.5v ? low shutdown current: <1a ? build in thermal, ocp, uvlo, ovp ? available in space saving packages: ? 16-ball 1.95mm x 1.95mm csp package ? 16-pin qfn4x4 package applications ? wireless or cellular handsets ? portable dvd player ? personal digital assistants (pdas ) ? electronic dictionaries ? digital still cameras pin assignments
pam8902a document number: dsxxxxx rev. 1 - 3 2 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated typical applications circuit pin descriptions bump (csp) pin number (qfn) pin name function a1 13 pvcc audio amplifier power supply a2 1 vout boost convertor output a3 2 sw boost convertor switching node a4 4 pgnd1 boost convertor power ground b1 15 outp positive differential audio output b2 3 vset boost convertor output voltage setting(8v,12v,17.5v) b3 5 comp boost convertor compensation b4 6 avdd power supply c1 14 outn negative differential audio output c2 11 gset amplifiergain setting. (refer to "application notes") c3 7 vcm common mode bypass cap c4 8 agnd analog ground d1 13 pgnd2 class d powerground d2 12 ena whole chip enable d3 10 inn negative differential audio input d4 9 inp positive differential audio input
pam8902a document number: dsxxxxx rev. 1 - 3 3 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated functional block diagram absolute maximum ratings (@t a = +25c, unless otherwise specified.) these are stress ratings only and functional operation is not implied. exposure to absolute maximum ratings for prolonged time periods may affect device reliability. all voltages are with respect to ground. parameter rating unit supply voltage 6.0 v input voltage -0.3 to v dd +0.3 maximum junction temperature +150 c storage temperature -65 to +150 soldering temperature 250, 10 sec recommended operating conditions (@t a = +25c, unless otherwise specified.) parameter rating unit supply voltage range 2.7 to 5.5 v ambient temperature range -40 to +85 c junction temperature range -40 to +125 c
pam8902a document number: dsxxxxx rev. 1 - 3 4 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated thermal information parameter package symbol max unit thermal resistance (junction to ambient) csp ja 90 ? 220 c/w qfn4x4-16 37 thermal resistance (junction to case) csp jc 75 qfn4x4-16 2 electrical characteristics (@t a = +25c, v dd = 3.6v, c l = 1f, v set floating, r load = 10 ? , l load = 22h with external schottky di odes, unless otherwise specified.) parameter symbol test conditions min typ max units input voltage v dd 2.7 5.5 v quiescent current i q en > 1.2v, v set = high 30 48 ma en > 1.2v, v set = floating 10 18 en > 1.2v, v set = gnd 5 12 shutdown current i sd en = 0v 0.1 1 a wake-up time t wu en from low to high 40 ms chip enable v eh 1.2 v chip disable v el 0.4 gset/ vset high v h v dd -0.5 v dd v gset/ vset floating v f 1 v dd -1 gset/ vset low v l 0 0.5 under voltage lockout threshold uvlo v dd from high to low 2.2 v under voltage lockout hysteresis uvlo(h) v dd from low to high 0.2 thermal shutdown threshold otp 150 c thermal shutdown lockout hysyeresis otp(h) 30 c boost converter output voltage v o 1 v set = low, no load 7.2 8.0 8.8 v v o 2 v set = floating, no load 10.8 12.0 13.2 v v o 3 v set = high, no load 16.0 17.5 19.0 v current limit c l average input current 0.8 a lowside mosfet r ds(on) r ls i o = 50ma 0.5 ? boost switching frequency f oscb 1.1 1.5 1.9 mhz over voltage protection threshold v ovp 18 v class d class d amplifier switching frequency f oscd input ac-gnd 225 375 475 khz common mode reject ratio cmrr v in = 100mv, v dd = 3.6v 60 db output offset voltage v os output offset voltage 5 50 mv r ds(on) r p high side 1.5 ? low side 0.6 ? closed-loop voltage gain a v 1 g set = high, v o = 1v rms 25 26 27 db a v 2 g set = floating, v o = 1v rms 21 22 23 a v 3 g set = low, v o = 1v rms 17 18 19 power supply reject ratio psrr 200m v pp supply ripple @ 217hz 70 db total harmonic distortion plus noise thd+n v o = 5vrms 0.3 % signal to noise ratio snr input ac ground, a-weighting 90 db
pam8902a document number: dsxxxxx rev. 1 - 3 5 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated typical performance characteristics (@t a = +25c, v dd = 3.6v, c l = 1f, l = 4.7h, v set floating, r load = 10 ? , l load = 22h, with external schottky diode, unless otherwise specified.)
pam8902a document number: dsxxxxx rev. 1 - 3 6 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated typical performance characteristics (cont.) (@t a = +25c, v dd = 3.6v, c l = 1f, l = 4.7h, v set floating, r load =10 ? , l load = 22h, with external schottky diode, unless otherwise specified.)
pam8902a document number: dsxxxxx rev. 1 - 3 7 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated application information select boost converter output voltage the v set pin sets the boost converter output voltage to 8v, 12v or 17.5v. v set pin configuration table as below: v set pin configuration min max pvcc voltage audio amplifier maximum output voltage high avdd ? 0.5 avdd 17.5v 11 v rms (v pp = 31.1v) floating 1v avdd ? 1v 12v 8 v rms (v pp = 22.6v) low gnd 0.5v 8v 5 v rms (v pp = 14.1v) gain setting and input resistance (r i ) gain setting function is only available in disable condition (ena = low) and need to fo llow the sequence as pull ena to low (di sable the ic) first, and change the gset voltage between high, floating, low, then pull ena to high (enable the ic). the input resistors (r i = r in + r ex ) set the gain of the amplifier according to equation 1 when anti-sat uration is inactive. g = 20 log [12.8*r f / (r in + r ex )] (db) g set r in r fb high 77.4k ? 122.6k ? floating 100k ? 100k ? low 122.6k ? 77.4k ? where r in is a 77.4k ? internal resistor, r ex is the external input resistor, r f is a 122.6k ? internal resistor. resistor matching is very important in fully differential amplifiers. the balance of the output on the reference voltage depends on matched ratios of the resistors . cmrr, psrr, and cancellation of the second harmonic distortion diminish if resistor mismatch occurs. t herefore, it is recommended to use 1% tol erance resistors or better to keep the performance optimized. ma tching is more important than overall tole rance. resistor arrays with 1% matchin g can be used with a tolerance greater than 1%. place the input resistors very close to the pam8902a to limit noise injection on the high-impedance nodes. for optimal performa nce the gain should be set to lower. lower gain allows the pam8902a to operat e at its best, and keeps a high voltage at the input making the inputs less susceptible to noise. in addition to these features, higher value of r i minimizes pop noise. anti-saturation/clipping function the anti-saturation circuitry detects the duty cycle of the pwm output. when the output starts to exhibit clipping, the gain is automatically decreased with an attack time of 100s per step a release time of 186ms per step. the following table describes the operation: variable description value gain the original gain of the devic e when the anti-saturation is inactive. 26db (g set = high) 22db (g set = floating) 18db (g set = low) attenuation range the gain control range when anti-saturation is active. -26db (g set = high) -22db (g set = floating) -18db (g set = low) step size gain adjust step size. 0.25db/step attack time the minimum time between two gain decrements. 100s release time the minimum time between two gain increments. 186ms
pam8902a document number: dsxxxxx rev. 1 - 3 8 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated application information (cont.) input capacitors (c i ) in the typical application, an input capacitor, c i , is required to allow the amplifier to bias t he input signal to the proper dc level for optimum operation. in this case, c i and the minimum input impedance r i form is a high-pass filter with the corner frequency determined in the follow equation: c r 2 1 f i i c = it is important to consider the value of c i as it directly affects the low frequency performance of the circuit. for example, when r i is 150k and the specification calls for a flat bass response are down to 150hz. equation is reconfigured as followed: r 2 1 c ifc i = when input resistance variat ion is considered, the c i is 7nf, so one would likely choose a value of 10nf. a further consideration for this capacitor is the leakage path from the i nput source through the input network (c i , r i + r f ) to the load. this leakage current creates a dc offset voltage at the input to the amplifier that reduces useful headr oom, especially in high gain applications. for this reason, a lo w-leakage tantalum or ceramic capacitor is the best choice. when polarized capacitors are used, the positive side of the capacitor should face the am plifier input in most applications as the dc level is held at v dd /2, which is likely higher than the source dc level. please note that it is important to confirm the capacitor polarity in the application. decoupling capacitor the pam8902 is a high-performance cmos audio amplifier that r equires adequate power supply decoupling to ensure the output tota l harmonic distortion (thd) as low as possible. the optimum decoupling is achieved by using two different types of capacitors that ta rget on different types of noise on the po wer supply leads. for higher frequency transients, spikes, or digital hash on the line, a good low equiva lent series-resistance (esr) ceramic cap acitor, typically 1f is placed as close as possi ble to the device avdd pin for the best operation. for filtering lower frequency noise signals, a large ceramic capacitor of 10f or greater placed near the avdd supply trace is recommended. external schottky diode use external schottky diode can get the best driving capability and efficiency. since internal power diode has limited driving capability, only in following conditions customer can remove the external schott ky diode to reduce the cost. 1. v set = low or floating and c l less than 1f. 2. the signal frequency less than 4khz. 3. haptic application (50?500hz). shutdown operation in order to reduce power consumption while not in use, the pam89 02a contains shutdown circuitry amplifier off when a logic low is placed on the ena pin. by switching the ena pin connected to gnd, the pam 8902a supply current draw will be minimized in idle mode. under-voltage lock-out (uvlo) the pam8902a incorporates circuitry designed to detect supply voltage. when the supply vo ltage drops to 2.2v or below, the pam8 902a goes into a state of shutdown, and the device comes out of its shutdown state and restore to normal function only when reset the pow er supply or ena pin. over-temperature protection (otp) thermal protection on the pam8902a prevents the device from damage w hen the internal die temperature exceeds +150c. there is a 15c tolerance on this trip point from device to device. once the die temperature exce eds the set point, the device will enter the s hutdown state and the outputs are disabled, in this condition both outp and outn will become high impedance. this is not a latched fault. the the rmal fault is cleared once the temperature of the die dec reased by 30c. this large hysteresis will prevent motor boating sound well and the device begins normal operation at this point with no external system interaction.
pam8902a document number: dsxxxxx rev. 1 - 3 9 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated ordering information part number part marking package type standard package pam8902azer bn yw csp-16l 3000units/tape&reel PAM8902AKER p8902a xxxyw qfn4x4-16l 3000units/tape&reel marking information
pam8902a document number: dsxxxxx rev. 1 - 3 10 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated package outline dimensions (all dimensions in mm.) csp-16
pam8902a document number: dsxxxxx rev. 1 - 3 11 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated package outline dimensions (cont.) (all dimensions in mm.) qfn4x4-16
pam8902a document number: dsxxxxx rev. 1 - 3 12 of 12 www.diodes.com february 2013 ? diodes incorporated pam8902a a product line o f diodes incorporated important notice diodes incorporated makes no warranty of any kind, express or implied, with regards to this document, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries rese rve the right to make modifications, enhanc ements, improvements, corrections or ot her changes without further notice to this document and any product descri bed herein. diodes incorporated does not assume any liability ari sing out of the application or use of this document or an y product described herein; neither does di odes incorporated convey any license under its patent or trademark rights, nor the rights of others. any customer or us er of this document or products described herein in such applica tions shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability w hatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes inco rporated products for any unintended or una uthorized application, customers shall i ndemnify and hold diodes incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death a ssociated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or foreign patents pending. product names and markings noted herein may also be covered by one or more united states, international or foreign trademarks. this document is written in english but may be translated into multiple languages for reference. only the english version of t his document is the final and determinative format released by diodes incorporated. life support diodes incorporated products are specifically not authorized for use as critical component s in life support devices or systems without the express written approval of the chief executive offi cer of diodes incorporated. as used herein: a. life support devices or syst ems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when proper ly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support devic e or system whose failure to perform can be reasonably expect ed to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifi cations of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-rel ated requirements concerning the ir products and any use of diodes incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or s ystems-related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporate d and its representatives against any damages arisi ng out of the use of diodes incorporated pr oducts in such safety-critical, life suppor t devices or systems. copyright ? 2013, diodes incorporated www.diodes.com

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