unisonic technologies co., ltd lm4811 preliminary cmos ic www.unisonic.com.tw 1 of 9 copyright ? 2011 unisonic technologies co., ltd qw-r502-560.a dual 105mw headphone amplifier with digital volume control and shutdown mode ? description the utc lm4811 is a dual audio power amplifier with digital volume control and shutdown mode function. it is featured in unity-gain stability. the digital volume control sets the amplifier?s gain from +12db to -33db in 16 discrete steps using a two-wire interface. the shutdown mode is externally controlled, active-high and micropower consumption. an internal thermal shutdown protection circuit is contained in the device. operating on a 5v powe r supply, it can drive 16 ? load at 105mw per channel of continuous average power with 0.1% (thd+n). this device is mainly used to provide customers with higher quality output power but less requi red external components. the utc lm4811 reduces the use of bootstr ap capacitors or snubber networks that make making it ideal for low-power portable systems applications. the utc lm4811 is generally applied in cellular phones, mp3, cd, dvd players, pda?s and other portable electronics. ? features * digital volume control range: +12db~ -33db * "click and pop" suppression circuitry * saving the use of bootstrap capacitors * low shutdown current ? ordering information ordering number lead free halogen free package packing LM4811L-SM2-R lm4811g-sm2-r msop-10 tape reel
lm4811 preliminary cmos ic unisonic technologies co., ltd 2 of 9 www.unisonic.com.tw qw-r502-560.a ? pin configuration 1 2 3 4 56 7 8 9 10 v dd v out2 v in2 shutdown up/dn gnd clock bypass v in1 v out1 msop-10 top view ? pin description pin no. pin name description 1 v out1 channel 1 output 2 v in1 channel 1 audio input 3 bypass connect to internal voltage divider for middle supply bias 4 clock external clock input for the volume control 5 gnd ground 6 up/dn volume up/down control 7 shutdown shutdown mode control input, high ac tive, place lm4811 into shutdown mode, when held high 8 v in2 channel 2 audio input 9 v out2 channel 2 output 10 v dd supply voltage
lm4811 preliminary cmos ic unisonic technologies co., ltd 3 of 9 www.unisonic.com.tw qw-r502-560.a ? block diagram digital volume control v in1 v dd 50k bypass v in2 50k up/dn clock gnd 20k 20k v out2 v out1 + + - - shutdown v dd 2 3 8 6 4 bias 7 5 9 1 10
lm4811 preliminary cmos ic unisonic technologies co., ltd 4 of 9 www.unisonic.com.tw qw-r502-560.a ? absolute maximum rating (t c = 25c, unless otherwise specified) parameter symbol ratings unit supply voltage v cc 6.0 v junction temperature t j 150 storage temperature t stg -65~ +150 notes: 1. absolute maximum ratings are those values be yond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? thermal data parameter symbol ratings unit junction to ambient ja 194 c/w junction to case jc 52 c/w ? operating ratings parameter symbol ratings unit supply voltage v cc 2.0 ~ 5.5 v operating temperature t a -40 ~ 85 c ? electrical characteristics (t a =25c, unless otherwise s pecified) (note 4, 5) for v dd =5v parameter symbol test conditions min typ max unit supply voltage v dd 2.0 5.5 v supply current i dd v in =0v, i o =0a 1.3 3.0 ma shutdown current i sd v in =0v 0.3 a output offset voltage v os v in =0v 4.0 50 mv r l =16 ? 105 mw output power p o thd+n=0.1%, f=1khz r l =32 ? 70 mw total harmonic distortion thd+n p o =50mw, r l =32 ? , f=20hz~20khz 0.3 % channel separation crosstalk r l =32 ? , f=1khz, p o =70mw 100 db power supply rejection ratio psrr c b =1.0 f,v ripple =100mv pp , f=217hz 60 db high v ih 1.4 v input voltage (clock, up/dn, shutdown) low v il 0.4 v input referred minimum gain -33 db digital volume range input referred maximum gain +12 db digital volume stepsize all 16 discrete steps 3.0 db stepsize error all 16 discrete steps 0.3 db channel-to-channel volume tracking error all gain settings from -33db ~ +12db 0.15 db shutdown attenuation shutdown mode active -100 db
lm4811 preliminary cmos ic unisonic technologies co., ltd 5 of 9 www.unisonic.com.tw qw-r502-560.a ? electrical characteristics(cont.) for v dd =3.3v parameter symbol test conditions min typ max unit supply current i dd v in =0v, i o =0a 1.1 ma shutdown current i sd v in =0v 0.3 a output offset voltage v os v in =0v 4.0 mv r l =16 ? 40 mw output power p o thd+n=0.1%, f=1khz r l =32 ? 28 mw total harmonic distortion thd+n p o =25mw, r l =32 ? , f=20hz~20khz 0.5 % power supply rejection ratio psrr c b =1.0 f,v ripple =100mv pp , f=217hz 60 db high v ih 1.4 v input voltage (clock, up/dn, shutdown) low v il 0.4 v input referred minimum gain -33 db digital volume range input referred maximum gain +12 db digital volume stepsize all 16 discrete steps 3.0 db stepsize error all 16 discrete steps 0.3 db channel-to-channel volume tracking error all gain settings from -33db ~ +12db 0.15 db shutdown attenuation shutdown mode active -100 db for v dd =2.6v parameter symbol test conditions min typ max unit supply current i dd v in =0v, i o =0a 1.0 ma shutdown current i sd v in =0v 0.3 a output offset voltage v os v in =0v 4.0 mv r l =16 ? 20 mw output power p o thd+n=0.1%, f=1khz r l =32 ? 16 mw total harmonic distortion thd+n p o =15mw, r l =32 ? , f=20hz~20khz 0.6 % power supply rejection ratio psrr c b =1.0 f,v ripple =100mv pp , f=217hz 60 db high v ih 1.4 v input voltage (clock, up/dn, shutdown) low v il 0.4 v input referred minimum gain -33 db digital volume range input referred maximum gain +12 db digital volume stepsize all 16 discrete steps 3.0 db stepsize error all 16 discrete steps 0.3 db channel-to-channel volume tracking error all gain settings from -33db ~ +12db 0.15 db shutdown attenuation shutdown mode active -75 db notes: 4. absolute maxi mum ratings indicate limits beyond which damage to the device may occur. 5. all voltages are measured with respec t to the ground pin, unless otherwise specified.
lm4811 preliminary cmos ic unisonic technologies co., ltd 6 of 9 www.unisonic.com.tw qw-r502-560.a ? application information digital volume control the utc lm4811 is dual audio power amplifier with digital volume control and shutdown mode function. the clock pin is drived by an external clock. it? s gain is controlled by the signals applied to the clock and up/dn inputs. the audio power amplifier?s gain is fixed by the signal s, which are applied to the clock and up/dn inputs. the gain is controlled by the logic voltage level applied to the up/dn pin at each rising edge of the clock signal. at each rising edge of the clock signal, when a logic high voltage leve l is applying to the up/dn pin, 3db is increased, in verse when a logic low voltage is applying to the up/dn pin, 3db is decreased on the contrary. for both the clock and up/dn inputs, the trigger point is 1.4v (min.) for a logic high level, and 0.4v (max.) for a logic low level. the utc lm4811 contains16 discrete gain settings varying from +12db (max.) to -33db (mi n.), amplifier?s gain is set to a default value of 0db during power on condition. however, when coming out of shutdown mode, the utc lm4811 will revert back to its previous gain setting. in order to avoid undesired state changes during transitions between v il and v ih , the utc lm4811 ?s clock and up/dn pins should be debounced. this will ensure co rrect operation of the di gital volume control. a microcontroller or microprocessor output is ex pected to drive the clock and up/dn pins. 1 0 0 1 up/dn clock volume default up up down down figure 2. timing diagram power supply bypassing to obtain low noise performance and high power supply rejection, proper supply bypassing is essentially needed for any power amplifier. capacitor on both the by pass and power supply pins should be placed closely as possible. bypass capacitor value is also critical as it directly affects t he device?s half-supply voltage stability and psrr. the stability and supply rejection increase as t he bypass capacitor?s value increases. in the typical applications, employing a 5v regulator with 10 f and a 0.1 f bypass capacitors which aid in supply stability. this, however, is not saving the need for bypassing the supply nodes of the utc lm4811 . the issue of selecting bypass capacitors, especially c b , is thus dependent upon desired low frequenc y psrr, click and pop pe rformance, system cost, and size constraints. shutdown function the utc lm4811 contains a bias circuitry shutdown to reduce power consumption while not is use. by applying a logic high to the shutdown pin, the sh utdown function is active. for a logic high level, the trigger point is 1.4v (min.), and 0.4v (max.) for a logic low. for a better shutdown performance, it is best to switch between ground and v dd . by switching the shutdown pin to v dd , the utc lm4811 supply current draw will be minimized in idle mode. whereas the device will be disabled with shutdown voltages less than v dd , the idle current may be greater than 0.3 a (typ.). in either case, the shutdown pin should be tied to a fixed voltage to avoid undesired state changes. in many applications, a microcontroller or microprocessor output is used to control t he shutdown circuitry. this provides a quick, smooth shutdown trans ition. another solution is to use a single-pole, single-throw switch in conjunction with an external pull-up resistor. when the swit ch is closed, the shutdown pin is connected to ground and enables the amplifier. if the switch is open, the external pull-up resistor, r pu , will disable the utc lm4811 . this scheme guarantees that the shutdo wn pin will not float, thus pr eventing undesired state changes.
lm4811 preliminary cmos ic unisonic technologies co., ltd 7 of 9 www.unisonic.com.tw qw-r502-560.a ? application information(cont.) proper selection of external components in applications, selection of external components when us ing integrated power amplifiers is critical for optimum device and system performance. moreover, t he vales of external components are al so important to consider as they directly affect the overall system quality. the utc lm4811 is tolerant to a variety external component combinations. the utc lm4811 is unity-gain stable, providing designers ma ximize system performance. low gain settings maximize signal-to-noise performance and minimizes thd+n. low gain configurations require large input signals to obtain a given output power. i nput signals reach 1vrms or higher are available from sources such as audio codecs. selection of input and output capacitor size another consideration is t he closed loop bandwidth besides gain. to a large extent, the bandwidth is dicated by the choice of external component s shown in figure 1. both the c i (input coupling capacitor) and the c o (output coupling capacitor) form first order high pass filters whic h limit low frequency response. the values of these capacitors should be based on the desired frequ ency response weighed against the following: large value input and output capacitor s are both expensive and space consum ing for portable designs. clearly a certain sized capacitor is needed to couple in low freque ncies without severe attenuat ion. but in many cases the speakers used in portable systems, whether internal or exter nal, have little ability to reproduce signals below 150hz. thus large input and output capacitors ma y not increase system performance. moreover, for the system cost and size, click and pop performance is affected by the size of the c i (input coupling capacitor). a larger input coupling capacitor requires more charge to reach its quiescent dc voltage (nominally 1/2 v dd ). this charge comes from the output via t he feedback and the pops are apt to be generated upon device enable. reducing the value of input coupling capa citor can minimize the turn on pops, which is based on necessary low frequency response. the value of bypass capacitor should be taken into c onsideration besides minimi zing the input and output capacitor values. for minimizing turn on pops, the bypass capacitor c b plays the most important role, since it determines how fast the utc lm4811 turns on. the slower the utc lm4811 ?s outputs ramp to their quiescent dc voltage (nominally 1/2 v dd ), the smaller the turn on pop. while the device will function properly, (no oscillations or motorboating), with c b equal to 1 f, the device will be much more susceptible to turn on clicks and pops. thus, a value of c b equal to 1 f or larger is recommended in all bu t the most cost sensitive designs. in addition, the type of capacitors should be given en ough consideration since diffe rent types of capacitors (tantalum, electrolytic, ceramic) have unique performan ce characteristics and may affect overall system performance.
lm4811 preliminary cmos ic unisonic technologies co., ltd 8 of 9 www.unisonic.com.tw qw-r502-560.a ? typical application circuit digital volume control bias audio input audio input c i 1 f v in1 + v dd r pu 100k v dd 50k + c b 1 f c i 1 f + v in2 50k up/dn clock gnd 20k 20k v out2 c o 100 f v out1 c o 100 f + + + + - - v dd c s 1 f + v dd v dd r p 100 c p 0.1 f r pd 100 bypass shutdown figure 1. typical audio amplifier application circuit * refer to the application information section for informa tion concerning proper selection of the input and output coupling capacitors.
lm4811 preliminary cmos ic unisonic technologies co., ltd 9 of 9 www.unisonic.com.tw qw-r502-560.a ? external components description pin no. pin name description 1 c i this is the input coupling capacitor. it blocks the dc voltage at, and couples the input signal to, the amplifier?s input terminals. c also creates a highpass filter with the internal input resistor, r i , at f c =1/(2 r i c i ). the minimum value of r i is 33k ? . refer to the section, proper selection of external components , for an explanation of how to determine the value of c i . 2 c s this is the supply bypass capacitor. it prov ides power supply filtering. refer to the application information section for proper placement and selection of the supply bypass capacitor. 3 c b this is the bypass pin capacitor. it provides hal f-supply filtering. re fer to the section, proper selection of external components , for information concerning proper placement and selection of c b . 4 c o this is the output coupling capacitor. it bl ocks the dc voltage at t he amplifier?s output and it forms a high pass filter with r l at fo = 1/(2 r l c o ) utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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