View KB4863M_1536816.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

kb4863 dual 2.2w audio amplifier plus stereo headphone function general description the kb4863 is a dual bridge-connected audio power ampli- fier which, when connected to a 5v supply, will deliver 2.2w toa4 ? load (note 1) or 2.5w to a 3 ? load (note 2) with less than 1.0% thd+n. in addition, the headphone input pin allows the amplifiers to operate in single-ended mode when driving stereo headphones. boomer audio power amplifiers were designed specifically to provide high quality output power from a surface mount package while requiring few external components. to sim- plify audio system design, the kb4863 combines dual bridge speaker amplifiers and stereo headphone amplifiers on one chip. the kb4863 features an externally controlled, low-power consumption shutdown mode, a stereo headphone amplifier mode, and thermal shutdown protection. it also utilizes cir- cuitry to reduce clicks and pops during device turn-on. note 1: an KB4863Mte or kb4863lq that has been properly mounted to a circuit board will deliver 2.2w into 4 ? . the other package options for the kb4863 will deliver 1.1w into 8 ? . see the application information sections for further information concerning the KB4863Mte and kb4863lq. note 2: an KB4863Mte or kb4863lq that has been properly mounted to a circuit board and forced-air cooled will deliver 2.5w into 3 ? . key specifications n p o at 1% thd+n n kb4863lq, 3 ? ,4 ? loads 2.5w(typ), 2.2w(typ) n KB4863Mte, 3 ? ,4 ? loads 2.5w(typ), 2.2w(typ) n KB4863Mte, 8 ? load 1.1w(typ) n kb4863, 8 ? 1.1w(typ) n single-ended mode thd+n at 75mw into 32 ? 0.5%(max) n shutdown current 0.7a(typ) n supply voltage range 2.0v to 5.5v features n stereo headphone amplifier mode n click and pop suppression circuitry n unity-gain stable n thermal shutdown protection circuitry n soic, dip, tssop and exposed-dap tssop and llp packages applications n multimedia monitors n portable and desktop computers n portable televisions typical application note: pin out shown for dip and so packages. refer to the connection diagrams for the pinout of the tssop, exposed-dap tssop, and exposed-dap llp packages. kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 1/19 rev: 1.1 2005-12-05
connection diagrams top view order number KB4863M, kb4863n m16b for so n16e for dip top view order number KB4863Mt mtc20 for tssop top view order number KB4863Mte mxa20a for exposed-dap tssop top view order number kb4863lq lqa24a for exposed-dap llp kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 2/19 rev: 1.1 2005-12-05
absolute maximum ratings (note 3) if military/aerospace specified devices are required, please contact the kingbor semiconductor sales office/ distributors for availability and specifications. supply voltage 6.0v storage temperature ?65?c to +150?c input voltage ?0.3v to v dd +0.3v power dissipation (note 4) internally limited esd susceptibility(note 5) 2000v esd susceptibility (note 6) 200v junction temperature 150?c solder information small outline package vapor phase (60 sec.) 215?c infrared (15 sec.) 220?c see an-450 surface mounting and their effects on product reliablilty for other methods of soldering surface mount devices. thermal resistance jc (typ) m16b 20?c/w ja (typ) m16b 80?c/w jc (typ) n16a 20?c/w ja (typ) n16a 63?c/w jc (typ) mtc20 20?c/w ja (typ) mtc20 80?c/w jc (typ) mxa20a 2?c/w ja (typ) mxa20a 41?c/w (note 7) ja (typ) mxa20a 51?c/w (note 8) ja (typ) mxa20a 90?c/w(note 9) jc (typ) lq24a 3.0?c/w ja (typ) lq24a 42?c/w (note 10) operating ratings temperature range t min t a t max ?40?c t a 85?c supply voltage 2.0v v dd 5.5v electrical characteristics for bridged-mode operation (notes 3, 11) the following specifications apply for v dd = 5v unless otherwise specified. limits apply for t a = 25?c. symbol parameter conditions kb4863 units (limits) typical (note 12) limit (note 13) v os output offset voltage v in = 0v 5 50 mv (max) p o output power (note 15) thd+n = 1%, f = 1khz (note 16) KB4863Mte, r l =3 ? kb4863lq, r l =3 ? 2.5 2.5 w w KB4863Mte, r l =4 ? kb4863lq, r l =4 ? 2.2 2.2 w w kb4863, r l =8 ? 1.1 1.0 w (min) thd+n = 10%, f = 1khz (note 16) KB4863Mte, r l =3 ? kb4863lq, r l =3 ? 3.2 3.2 w w kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 3/19 rev: 1.1 2005-12-05
electrical characteristics for bridged-mode operation (notes 3, 11) (continued) the following specifications apply for v dd = 5v unless otherwise specified. limits apply for t a = 25?c. symbol parameter conditions kb4863 units (limits) typical (note 12) limit (note 13) KB4863Mte, r l =4 ? kb4863lq, r l =4 ? 2.7 2.7 w w kb4863, r l =8 ? 1.5 w thd+n = 1%, f = 1khz, r l =32 ? 0.34 w thd+n total harmonic distortion+noise 20hz f 20khz, a vd =2 KB4863Mte, r l =4 ? ,p o =2w kb4863lq, r l =4 ? ,p o =2w 0.3 0.3 % kb4863, r l =8 ? ,p o = 1w 0.3 % psrr power supply rejection ratio v dd = 5v, v ripple = 200mv rms ,r l =8 ? , c b = 1.0f 67 db x talk channel separation f = 1khz, c b = 1.0f 90 db snr signal to noise ratio v dd = 5v, p o = 1.1w, r l =8 ? 98 db electrical characteristics for single-ended operation (notes 3, 4) the following specifications apply for v dd = 5v unless otherwise specified. limits apply for t a = 25?c. symbol parameter conditions kb4863 units (limits) typical (note 12) limit (note 13) v os output offset voltage v in = 0v 5 50 mv (max) p o output power thd+n = 0.5%, f = 1khz, r l =32 ? 85 75 mw (min) thd+n = 1%, f = 1khz, r l =8 ? 340 mw thd+n = 10%, f = 1khz, r l =8 ? 440 mw thd+n total harmonic distortion+noise a v = ?1, p o = 75mw, 20hz f 20khz, r l =32 ? 0.2 % psrr power supply rejection ratio c b = 1.0f, v ripple = 200mv rms , f = 1khz 52 db x talk channel separation f = 1khz, c b = 1.0f 60 db snr signal to noise ratio v dd = 5v, p o = 340mw, r l =8 ? 95 db note 3: absolute maximum ratings indicate limits beyond which damage to the device may occur. operating ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. electrical characteristics state dc and ac electrical specifications under particu lar test conditions which guarantee specific performance limits. this assumes that the device is within the operating ratings. specifications are not guaranteed for paramet ers where no limit is given, however, the typical value is a good indication of device performance. note 4: the maximum power dissipation is dictated by t jmax , ja , and the ambient temperature t a and must be derated at elevated temperatures. the maximum allowable power dissipation is p dmax =(t jmax ?t a )/ ja . for the kb4863, t jmax = 150?c. for the ja s for different packages, please see the application information section or the absolute maximum ratings section. note 5: human body model, 100 pf discharged through a 1.5 k ? resistor. note 6: machine model, 220 pfC240 pf discharged through all pins. note 7: the given ja is for an kb4863 packaged in an mxa20a with the exposed?dap soldered to an exposed 2in 2 area of 1oz printed circuit board copper. note 8: the given ja is for an kb4863 packaged in an mxa20a with the exposed?dap soldered to an exposed 1in 2 area of 1oz printed circuit board copper. note 9: the given ja is for an kb4863 packaged in an mxa20a with the exposed-dap not soldered to printed circuit board copper. note 10: the given ja is for an kb4863 packaged in an lqa24a with the exposed?dap soldered to an exposed 2in 2 area of 1oz printed circuit board copper. note 11: all voltages are measured with respect to the ground (gnd) pins unless otherwise specified. note 12: typicals are measured at 25?c and represent the parametric norm. note 13: limits are guaranteed to kingbors aoql (average outgoing quality level). note 14: the quiescent power supply current depends on the offset voltage when a practical load is connected to the amplifier. note 15: output power is measured at the device terminals. note 16: when driving 3 ? or 4 ? and operating on a 5v supply, the kb4863lq and KB4863Mte must be mounted to the circuit board that has a minimum of 2.5in 2 of exposed, uninterrupted copper area connected to the llp packages exposed dap. kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 4/19 rev: 1.1 2005-12-05
typical performance characteristics mte specific characteristics KB4863Mte thd+n vs output power KB4863Mte thd+n vs frequency KB4863Mte thd+n vs output power KB4863Mte thd+n vs frequency KB4863Mte power dissipation vs power output KB4863Mte power derating curve kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 5/19 rev: 1.1 2005-12-05
typical performance characteristics mte specific characteristics (continued) KB4863Mte (note 17) power derating curve note 17: this curve shows the KB4863Mtes thermal dissipation ability at different ambient temperatures given these conditions: 500lfpm + jedec board: the part is soldered to a 1s2p 20-lead exposed-dap tssop test board with 500 linear feet per minute of forced-air flow across it. board information - copper dimensions: 74x74mm, copper coverage: 100% (buried layer) and 12% (top/bottom layers), 16 vias under the exposed-dap. 500lfpm + 2.5in 2 : the part is soldered to a 2.5in 2 , 1 oz. copper plane with 500 linear feet per minute of forced-air flow across it. 2.5in 2 : the part is soldered to a 2.5in 2 , 1oz. copper plane. not attached: the part is not soldered down and is not forced-air cooled. non-mte specific characteristics thd+n vs frequency thd+n vs frequency thd+n vs frequency thd+n vs output power kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 6/19 rev: 1.1 2005-12-05
non-mte specific characteristics (continued) thd+n vs output power thd+n vs output power thd+n vs output power thd+n vs frequency thd+n vs output power thd+n vs frequency kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 7/19 rev: 1.1 2005-12-05
non-mte specific characteristics (continued) output power vs load resistance power dissipation vs supply voltage output power vs supply voltage output power vs supply voltage output power vs supply voltage output power vs load resistance kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 8/19 rev: 1.1 2005-12-05
non-mte specific characteristics (continued) output power vs load resistance power dissipation vs output power dropout voltage vs supply voltage power derating curve power dissipation vs output power noise floor kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 9/19 rev: 1.1 2005-12-05
non-mte specific characteristics (continued) channel separation channel separation power supply rejection ratio open loop frequency response supply current vs supply voltage kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 10/19 rev: 1.1 2005-12-05
external components description (refer to figure 1 .) components functional description 1. r i the inverting input resistance, along with r f , set the closed-loop gain. r i , along with c i , form a high pass filter with f c = 1/(2 r i c i ). 2. c i the input coupling capacitor blocks dc voltage at the amplifiers input terminals. c i , along with r i , create a highpass filter with f c = 1/(2 r i c i ). refer to the section, selecting proper external components , for an explanation of determining the value of c i . 3. r f the feedback resistance, along with r i , set the closed-loop gain. 4. c s the supply bypass capacitor. refer to the power supply bypassing section for information about properly placing, and selecting the value of, this capacitor. 5. c b the capacitor, c b , filters the half-supply voltage present on the bypass pin. refer to the selecting proper external components section for information concerning proper placement and selecting c b s value. application information exposed-dap package pcb mounting considerations the kb4863s exposed-dap (die attach paddle) packages (mte and lq) provide a low thermal resistance between the die and the pcb to which the part is mounted and soldered. this allows rapid heat transfer from the die to the surround- ing pcb copper traces, ground plane and, finally, surround- ing air. the result is a low voltage audio power amplifier that produces 2.2w at 1% thd with a 4 ? load. this high power is achieved through careful consideration of necessary ther- mal design. failing to optimize thermal design may compro- mise the kb4863s high power performance and activate unwanted, though necessary, thermal shutdown protection. the mte and lq packages must have their daps soldered to a copper pad on the pcb. the daps pcb copper pad is connected to a large plane of continuous unbroken copper. this plane forms a thermal mass and heat sink and radiation area. place the heat sink area on either outside plane in the case of a two-sided pcb, or on an inner layer of a board with more than two layers. connect the dap copper pad to the inner layer or backside copper heat sink area with 32(4x8) (mte) or 6(3x2) (lq) vias. the via diameter should be 0.012in - 0.013in with a 1.27mm pitch. ensure efficient ther- mal conductivity by plating-through and solder-filling the vias. best thermal performance is achieved with the largest prac- tical copper heat sink area. if the heatsink and amplifier share the same pcb layer, a nominal 2.5in 2 (min) area is necessary for 5v operation with a 4 ? load. heatsink areas not placed on the same pcb layer as the kb4863 should be 5in 2 (min) for the same supply voltage and load resistance. the last two area recommendations apply for 25?c ambient temperature. increase the area to compensate for ambient temperatures above 25?c. in systems using cooling fans, the KB4863Mte can take advantage of forced air cooling. with an air flow rate of 450 linear-feet per minute and a 2.5in 2 exposed copper or 5.0in 2 inner layer copper plane heatsink, the KB4863Mte can continuously drive a 3 ? load to full power. the kb4863lq achieves the same output power level without forced air cooling. in all circumstances and conditions, the junction temperature must be held below 150?c to prevent activating the kb4863s thermal shutdown protection. the kb4863s power de-rating curve in the typi- cal performance characteristics shows the maximum power dissipation versus temperature. example pcb layouts for the exposed-dap tssop and llp packages are shown in the demonstration board layout section. further de- tailed and specific information concerning pcb layout, fabri- cation, and mounting an llp package is available from kingbor semiconductors package engineering group. when contacting them, ask for preliminary application note for the assembly of the llp package on a printed circuit board, revision a dated 11/24/05. pcb layout and supply regulation considerations for driving 3 ? and 4 ? loads power dissipated by a load is a function of the voltage swing across the load and the loads impedance. as load imped- ance decreases, load dissipation becomes increasingly de- pendent on the interconnect (pcb trace and wire) resistance between the amplifier output pins and the loads connec- tions. residual trace resistance causes a voltage drop, which results in power dissipated in the trace and not in the load as desired. for example, 0.1 ? trace resistance reduces the output power dissipated by a 4 ? load from 2.1w to 2.0w. this problem of decreased load dissipation is exacerbated as load impedance decreases. therefore, to maintain the highest load dissipation and widest output voltage swing, pcb traces that connect the output pins to a load must be as wide as possible. poor power supply regulation adversely affects maximum output power. a poorly regulated supplys output voltage decreases with increasing load current. reduced supply voltage causes decreased headroom, output signal clipping, and reduced output power. even with tightly regulated sup- plies, trace resistance creates the same effects as poor supply regulation. therefore, making the power supply traces as wide as possible helps maintain full output voltage swing. kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 11/19 rev: 1.1 2005-12-05
application information (continued) bridge configuration explanation as shown in figure 1 , the kb4863 consists of two pairs of operational amplifiers, forming a two-channel (channel a and channel b) stereo amplifier. (though the following discusses channel a, it applies equally to channel b.) external resistors r f and r i set the closed-loop gain of amp1a, whereas two internal 20k ? resistors set amp2as gain at -1. the kb4863 drives a load, such as a speaker, connected between the two amplifier outputs, -outa and +outa. figure 1 shows that amp1as output serves as amp2as input. this results in both amplifiers producing signals iden- tical in magnitude, but 180? out of phase. taking advantage of this phase difference, a load is placed between -outa and +outa and driven differentially (commonly referred to as bridge mode). this results in a differential gain of a vd =2x(r f /r i ) (1) bridge mode amplifiers are different from single-ended am- plifiers that drive loads connected between a single amplifi- ers output and ground. for a given supply voltage, bridge mode has a distinct advantage over the single-ended con- figuration: its differential output doubles the voltage swing across the load. this produces four times the output power when compared to a single-ended amplifier under the same conditions. this increase in attainable output power as- sumes that the amplifier is not current limited or that the output signal is not clipped. to ensure minimum output sig- nal clipping when choosing an amplifiers closed-loop gain, refer to the audio power amplifier design section. another advantage of the differential bridge output is no net dc voltage across the load. this is accomplished by biasing channel as and channel bs outputs at half-supply. this eliminates the coupling capacitor that single supply, single-ended amplifiers require. eliminating an output cou- pling capacitor in a single-ended configuration forces a single-supply amplifiers half-supply bias voltage across the load. this increases internal ic power dissipation and may permanently damage loads such as speakers. power dissipation power dissipation is a major concern when designing a successful single-ended or bridged amplifier. equation (2) states the maximum power dissipation point for a single- ended amplifier operating at a given supply voltage and driving a specified output load p dmax =(v dd ) 2 /(2 2 r l ) single-ended (2) however, a direct consequence of the increased power de- livered to the load by a bridge amplifier is higher internal power dissipation for the same conditions. the kb4863 has two operational amplifiers per channel. the maximum internal power dissipation per channel operating in the bridge mode is four times that of a single-ended ampli- fier. from equation (3), assuming a 5v power supply and an 4 ? load, the maximum single channel power dissipation is 1.27w or 2.54w for stereo operation. p dmax =4x(v dd ) 2 /(2 2 r l ) bridge mode (3) the lm4973s power dissipation is twice that given by equa- tion (2) or equation (3) when operating in the single-ended * refer to the section proper selection of external components, for a detailed discussion of c b size. figure 1. typical audio amplifier application circuit pin out shown for dip and so packages. refer to the connection diagrams for the pinout of the tssop, exposed-dap tssop, and exposed-dap llp packages. kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 12/19 rev: 1.1 2005-12-05
application information (continued) mode or bridge mode, respectively. twice the maximum power dissipation point given by equation (3) must not ex- ceed the power dissipation given by equation (4): p dmax =(t jmax ?t a )/ ja (4) the kb4863s t jmax = 150?c. in the lq (llp) package soldered to a dap pad that expands to a copper area of 5in 2 on a pcb, the kb4863s ja is 20?c/w. in the mte package soldered to a dap pad that expands to a copper area of 2in 2 on a pcb , the kb4863s ja is 41?c/w. at any given ambient temperature t j\a , use equation (4) to find the maxi- mum internal power dissipation supported by the ic packag- ing. rearranging equation (4) and substituting pdmax for pdmax results in equation (5). this equation gives the maximum ambient temperature that still allows maximum stereo power dissipation without violating the kb4863s maximum junction temperature. t a =t jmax ?2xp dmax ja (5) for a typical application with a 5v power supply and an 4 ? load, the maximum ambient temperature that allows maxi- mum stereo power dissipation without exceeding the maxi- mum junction temperature is approximately 99?c for the llp package and 45?c for the mte package. t jmax =p dmax ja +t a (6) equation (6) gives the maximum junction temperature t j - max . if the result violates the kb4863s 150?c, reduce the maximum junction temperature by reducing the power sup- ply voltage or increasing the load resistance. further allow- ance should be made for increased ambient temperatures. the above examples assume that a device is a surface mount part operating around the maximum power dissipation point. since internal power dissipation is a function of output power, higher ambient temperatures are allowed as output power or duty cycle decreases. if the result of equation (2) is greater than that of equation (3), then decrease the supply voltage, increase the load impedance, or reduce the ambient temperature. if these measures are insufficient, a heat sink can be added to reduce ja . the heat sink can be created using additional copper area around the package, with connections to the ground pin(s), supply pin and amplifier output pins. external, solder attached smt heatsinks such as the thermalloy 7106d can also improve power dissipation. when adding a heat sink, the ja is the sum of jc , cs , and sa .( jc is the junction?to?case thermal impedance, cs is the case?to?sink thermal impedance, and sa is the sink?to?ambient thermal impedance.) refer to the typical performance characteris- tics curves for power dissipation information at lower output power levels. power supply bypassing as with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. applications that employ a 5v regulator typically use a 10f in parallel with a 0.1f filter capacitors to stabi- lize the regulators output, reduce noise on the supply line, and improve the supplys transient response. however, their presence does not eliminate the need for a local 1.0f tantalum bypass capacitance connected between the kb4863s supply pins and ground. do not substitute a ce- ramic capacitor for the tantalum. doing so may cause oscil- lation in the output signal. keep the length of leads and traces that connect capacitors between the kb4863s power supply pin and ground as short as possible. connecting a 1f capacitor, c b , between the bypass pin and ground improves the internal bias voltages stability and improves the amplifiers psrr. the psrr improvements increase as the bypass pin capacitor value increases. too large, how- ever, increases turn-on time and can compromise amplifiers click and pop performance. the selection of bypass capaci- tor values, especially c b , depends on desired psrr require- ments, click and pop performance (as explained in the sec- tion, proper selection of external components ), system cost, and size constraints. micro-power shutdown the voltage applied to the shutdown pin controls the kb4863s shutdown function. activate micro-power shut- down by applying v dd to the shutdown pin. when active, the kb4863s micro-power shutdown feature turns off the amplifiers bias circuitry, reducing the supply current. the logic threshold is typically v dd /2. the low 0.7a typical shutdown current is achieved by applying a voltage that is as near as v dd as possible to the shutdown pin. a voltage thrat is less than v dd may increase the shutdown current. there are a few ways to control the micro-power shutdown. these include using a single-pole, single-throw switch, a microprocessor, or a microcontroller. when using a switch, connect an external 10k ? pull-up resistor between the shutdown pin and v dd . connect the switch between the shutdown pin and ground. select normal amplifier opera- tion by closing the switch. opening the switch connects the shutdown pin to v dd through the pull-up resistor, activat- ing micro-power shutdown. the switch and resistor guaran- tee that the shutdown pin will not float. this prevents unwanted state changes. in a system with a microprocessor or a microcontroller, use a digital output to apply the control voltage to the shutdown pin. driving the shutdown pin with active circuitry eliminates the pull up resistor. table 1. logic level truth table for shutdown and hp-in operation shutdown hp-in pin operational mode low logic low bridged amplifiers low logic high single-ended amplifiers high logic low micro-power shutdown high logic high micro-power shutdown hp-in function applying a voltage between 4v and v dd to the kb4863s hp-in headphone control pin turns off amp2a and amp2b, muting a bridged-connected load. quiescent current con- sumption is reduced when the ic is in this single-ended mode. figure 2 shows the implementation of the kb4863s head- phone control function. with no headphones connected to the headphone jack, the r1-r2 voltage divider sets the voltage applied to the hp-in pin (pin 16) at approximately 50mv. this 50mv enables amp1b and amp2b, placing the kb4863s in bridged mode operation. the output coupling capacitor blocks the amplifiers half-supply dc voltage, pro- tecting the headphones. while the kb4863 operates in bridged mode, the dc poten- tial across the load is essentially 0v. the hp-in threshold is set at 4v. therefore, even in an ideal situation, the output swing cannot cause a false single-ended trigger. connecting headphones to the headphone jack disconnects the head- kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 13/19 rev: 1.1 2005-12-05
application information (continued) phone jack contact pin from -outa and allows r1 to pull the hp sense pin up to v dd . this enables the headphone func- tion, turns off amp2a and amp2b, and mutes the bridged speaker. the amplifier then drives the headphones, whose impedance is in parallel with resistor r2 and r3. these resistors have negligible effect on the kb4863s output drive capability since the typical impedance of headphones is 32 ? . figure 2 also shows the suggested headphone jack electri- cal connections. the jack is designed to mate with a three-wire plug. the plugs tip and ring should each carry one of the two stereo output signals, whereas the sleeve should carry the ground return. a headphone jack with one control pin contact is sufficient to drive the hp-in pin when connecting headphones. a microprocessor or a switch can replace the headphone jack contact pin. when a microprocessor or switch applies a voltage greater than 4v to the hp-in pin, a bridge-connected speaker is muted and amp1a and amp2a drive a pair of headphones. selecting proper external components optimizing the kb4863s performance requires properly se- lecting external components. though the kb4863 operates well when using external components with wide tolerances, best performance is achieved by optimizing component val- ues. the kb4863 is unity-gain stable, giving a designer maximum design flexibility. the gain should be set to no more than a given application requires. this allows the amplifier to achieve minimum thd+n and maximum signal-to-noise ra- tio. these parameters are compromised as the closed-loop gain increases. however, low gain demands input signals with greater voltage swings to achieve maximum output power. fortunately, many signal sources such as audio co- decs have outputs of 1v rms (2.83v p-p ). please refer to the audio power amplifier design section for more informa- tion on selecting the proper gain. input capacitor value selection amplifying the lowest audio frequencies requires high value input coupling capacitor (c i in figure 1 ). a high value capaci- tor can be expensive and may compromise space efficiency in portable designs. in many cases, however, the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150hz. applications using speakers with this limited frequency response reap little improvement by using large input capacitor. besides effecting system cost and size, c i has an affect on the kb4863s click and pop performance. when the supply voltage is first applied, a transient (pop) is created as the charge on the input capacitor changes from zero to a quies- cent state. the magnitude of the pop is directly proportional to the input capacitors size. higher value capacitors need more time to reach a quiescent dc voltage (usually v dd /2) when charged with a fixed current. the amplifiers output charges the input capacitor through the feedback resistor, r f . thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired -3db frequency. a shown in figure 1 , the input resistor (r i ) and the input capacitor, c i produce a ?3db high pass filter cutoff frequency that is found using equation (7). (7) as an example when using a speaker with a low frequency limit of 150hz, c i , using equation (4), is 0.063f. the 1.0f c i shown in figure 1 allows the kb4863 to drive high effi- ciency, full range speaker whose response extends below 30hz. bypass capacitor value selection besides minimizing the input capacitor size, careful consid- eration should be paid to value of c b , the capacitor con- nected to the bypass pin. since c b determines how fast the kb4863 settles to quiescent operation, its value is critical when minimizing turn?on pops. the slower the kb4863s outputs ramp to their quiescent dc voltage (nominally 1/2 v dd ), the smaller the turn?on pop. choosing c b equal to 1.0f along with a small value of c i (in the range of 0.1f to 0.39f), produces a click-less and pop-less shutdown func- tion. as discussed above, choosing c i no larger than neces- sary for the desired bandwidth helps minimize clicks and pops. optimizing click and pop reduction performance the kb4863 contains circuitry to minimize turn-on and shut- down transients or clicks and pop. for this discussion, turn-on refers to either applying the power supply voltage or when the shutdown mode is deactivated. while the power supply is ramping to its final value, the kb4863s internal amplifiers are configured as unity gain buffers. an internal current source changes the voltage of the bypass pin in a controlled, linear manner. ideally, the input and outputs track the voltage applied to the bypass pin. the gain of the internal amplifiers remains unity until the voltage on the bypass pin reaches 1/2 v dd . as soon as the voltage on the bypass pin is stable, the device becomes fully operational. although the bypass pin current cannot be modified, chang- ing the size of c b alters the devices turn-on time and the magnitude of clicks and pops. increasing the value of c b reduces the magnitude of turn-on pops. however, this pre- figure 2. headphone circuit kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 14/19 rev: 1.1 2005-12-05
application information (continued) sents a tradeoff: as the size of c b increases, the turn-on time increases. there is a linear relationship between the size of c b and the turn-on time. here are some typical turn-on times for various values of c b : c b t on 0.01f 20 ms 0.1f 200 ms 0.22f 440 ms 0.47f 940 ms 1.0f 2 sec in order eliminate clicks and pops, all capacitors must be discharged before turn-on. rapidly switching v dd may not allow the capacitors to fully discharge, which may cause clicks and pops. in a single-ended configuration, the output is coupled to the load by c out . this capacitor usually has a high value. c out discharges through internal 20k ? resistors. depending on the size of c out , the discharge time constant can be relatively large. to reduce transients in single-ended mode, an external 1k ? -5k ? resistor can be placed in parallel with the internal 20k ? resistor. the tradeoff for using this resistor is increased quiescent current. no load stability the kb4863 may exhibit low level oscillation when the load resistance is greater than 10k ? . this oscillation only occurs as the output signal swings near the supply voltages. pre- vent this oscillation by connecting a 5k ? between the output pins and ground. audio power amplifier design audio amplifier design: driving 1w into an 8 ? load the following are the desired operational parameters: power output: 1wrms load impedance: 8 ? input level: 1vrms input impedance: 20k ? bandwidth: 100hz?20 khz 0.25 db the design begins by specifying the minimum supply voltage necessary to obtain the specified output power. one way to find the minimum supply voltage is to use the output power vs supply voltage curve in the typical performance char- acteristics section. another way, using equation (4), is to calculate the peak output voltage necessary to achieve the desired output power for a given load impedance. to ac- count for the amplifiers dropout voltage, two additional volt- ages, based on the dropout voltage vs supply voltage in the typical performance characteristics curves, must be added to the result obtained by equation (8). the result in equation (9). (8) v dd (v outpeak +(v od top +v od bot )) (9) the output power vs supply voltage graph for an 8 ? load indicates a minimum supply voltage of 4.6v. this is easily met by the commonly used 5v supply voltage. the additional voltage creates the benefit of headroom, allowing the kb4863 to produce peak output power in excess of 1w without clipping or other audible distortion. the choice of supply voltage must also not create a situation that violates maximum power dissipation as explained above in the power dissipation section. after satisfying the kb4863s power dissipation require- ments, the minimum differential gain is found using equation (10). (10) thus, a minimum gain of 2.83 allows the kb4863s to reach full output swing and maintain low noise and thd+n perfor- mance. for this example, let a vd =3. the amplifiers overall gain is set using the input (r i ) and feedback (r f ) resistors. with the desired input impedance set at 20k ? , the feedback resistor is found using equation (11). r f /r i =a vd /2 (11) the value of r f is 30k ? . the last step in this design example is setting the amplifiers ?3db frequency bandwidth. to achieve the desired 0.25db pass band magnitude variation limit, the low frequency re- sponse must extend to at least one?fifth the lower bandwidth limit and the high frequency response must extend to at least five times the upper bandwidth limit. the gain variation for both response limits is 0.17db, well within the 0.25db desired limit. the results are an f l = 100hz/5 = 20hz (12) and an f h = 20khzx5 = 100khz (13) as mentioned in the external components section, r i and c i create a highpass filter that sets the amplifiers lower bandpass frequency limit. find the coupling capacitors value using equation (12). the result is 1/(2 * 20k ? * 20hz) = 0.398f (14) use a 0.39f capacitor, the closest standard value. the product of the desired high frequency cutoff (100khz in this example) and the differential gain, a vd , determines the upper passband response limit. with a vd = 3 and f h = 100khz, the closed-loop gain bandwidth product (gbwp) is 300khz. this is less than the kb4863s 3.5mhz gbwp. with this margin, the amplifier can be used in designs that require more differential gain while avoiding performance-lrestricting bandwidth limitations. recommended printed circuit board layout figures 3 through 6 show the recommended two-layer pc board layout that is optimized for the 20-pin mte-packaged kb4863 and associated external components. figures 7 through 11 show the recommended four-layer pc board layout that is optimized for the 24-pin lq-packaged kb4863 and associated external components. these circuits are de- signed for use with an external 5v supply and 4 ? speakers. these circuit boards are easy to use. apply 5v and ground to the boards v dd and gnd pads, respectively. connect 4 ? speakers between the boards -outa and +outa and outb and +outb pads. kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 15/19 rev: 1.1 2005-12-05
physical dimensions inches (millimeters) unless otherwise noted 16-lead (0.300" wide) molded small outline package, jedec order number KB4863M package number m16b 16-lead (0.300" wide) molded dual-in-line package order number kb4863n package number n16e kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 16/19 rev: 1.1 2005-12-05
physical dimensions inches (millimeters) unless otherwise noted (continued) 20-lead molded pkg, tssop, jedec, 4.4mm body width order number KB4863Mt package number mtc20 kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 17/19 rev: 1.1 2005-12-05
physical dimensions inches (millimeters) unless otherwise noted (continued) 20-lead molded tssop, exposed pad, 6.5x4.4x0.9mm order number KB4863Mte package number mxa20a kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 18/19 rev: 1.1 2005-12-05
physical dimensions inches (millimeters) unless otherwise noted (continued) 24-lead molded pkg, leadframe package llp order number kb4863lq ns package number lqa24a kingbortechnologyco.,ltd tel:(86)0755-83095458 fax:(86)0755-88364052 kb4863 19/19 rev: 1.1 2005-12-05

▲Up To Search▲

Price & Availability of KB4863M

	To Download KB4863M Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .