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lm4901 1.6 watt audio power amplifier with selectable shutdown logic level general description the lm4901 is an audio power amplifier primarily designed for demanding applications in mobile phones and other por- table communication device applications. it is capable of delivering 1 watt of continuous average power to an 8 w btl load and 1.6 watts of continuous avearge power to a 4 w btl load with less than 1% distortion (thd+n) from a 5v dc power supply. boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. the lm4901 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage appli- cations where minimal power consumption is a primary re- quirement. the lm4901 features a low-power consumption shutdown mode. to facilitate this, shutdown may be enabled by either logic high or low depending on mode selection. driving the shutdown mode pin either high or low enables the shutdown pin to be driven in a likewise manner to enable shutdown. the lm4901 contains advanced pop & click circuitry which eliminates noise which would otherwise occur during turn-on and turn-off transitions. the lm4901 is unity-gain stable and can be configured by external gain-setting resistors. key specifications j improved psrr at 217hz & 1khz 62db j power output at 5.0v, 1% thd, 4 w 1.6w (typ) j power output at 5.0v, 1% thd, 8 w 1.07w (typ) j power output at 3.0v, 1% thd, 4 w 525mw (typ) j power output at 3.0v, 1% thd, 8 w 390mw (typ) j shutdown current 0.1a (typ) features n available in space-saving packages: llp, micro smd, and msop n ultra low current shutdown mode n btl output can drive capacitive loads n improved pop & click circuitry eliminates noise during turn-on and turn-off transitions n 2.0 - 5.5v operation n no output coupling capacitors, snubber networks or bootstrap capacitors required n unity-gain stable n external gain configuration capability n user selectable shutdown high or low logic level applications n mobile phones n pdas n portable electronic devices typical application boomer ? is a registered trademark of national semiconductor corporation. ds200198-1 figure 1. typical audio amplifier application circuit may 2002 lm4901 1.6 watt audio power amplifier with selectable shutdown logic level ? 2002 national semiconductor corporation ds200198 www.national.com
connection diagrams 9 bump micro smd ds200198-23 top view order number LM4901IBL, LM4901IBLx see ns package number bla09aac mini small outline (msop) package ds200198-36 top view order number lm4901mm see ns package number mub10a llp package ds200198-b3 top view order number lm4901ld see ns package number lda10b micro smd marking ds200198-70 top view x - date code t - die traceability g - boomer family q - LM4901IBL msop marking ds200198-71 top view g - boomer family c1 - lm4901mm ds200198-b4 lm4901 www.national.com 2
absolute maximum ratings (note 2) if military/aerospace specified devices are required, please contact the national semiconductor sales office/ distributors for availability and specifications. supply voltage (note 11) 6.0v storage temperature ?65c to +150c input voltage ?0.3v to v dd +0.3v power dissipation (notes 3, 13) internally limited esd susceptibility (note 4) 2000v esd susceptibility (note 5) 200v junction temperature 150c thermal resistance q ja (micro smd) (note 12) 180c/w q jc (msop) 56c/w q ja (msop) 190c/w q ja (llp) 63c/w (note 14) q jc (llp) 12c/w (note 14) soldering information see an-1112 'microsmd wafers level chip scale package.' see an-1187 'leadless leadframe package (llp).' operating ratings temperature range t min t a t max ?40c t a 85c supply voltage 2.0v v dd 5.5v electrical characteristics v dd =5v (notes 1, 2) the following specifications apply for the circuit shown in figure 1, unless otherwise specified. limits apply for t a = 25c. symbol parameter conditions lm4901 units (limits) typical limit (note 6) (notes 7, 9) i dd quiescent power supply current v in = 0v, i o = 0a, no load 3 7 ma (max) v in = 0v, i o = 0a, 8 w load 4 10 ma (max) i sd shutdown current v sd =v sd mode (note 8) 0.1 2.0 a (max) v sdih shutdown voltage input high v sd mode =v dd 1.5 v (min) v sdil shutdown voltage input low v sd mode =v dd 1.3 v (max) v sdih shutdown voltage input high v sd mode = gnd 1.5 v (min) v sdil shutdown voltage input low v sd mode = gnd 1.3 v (max) v os output offset voltage 7 50 mv (max) r out resistor output to gnd (note 10) 8.5 9.7 k w (max) 7.0 k w (min) p o output power (8 w ) thd = 1% (max) ;f=1khz 1.07 0.9 w (min) (4 w ) (notes 14, 15) thd = 1% (max) ;f=1khz 1.6 w t wu wake-up time 100 ms (max) thd+n total harmonic distortion+noise p o = 0.5 wrms ; f = 1khz 0.2 % psrr power supply rejection ratio v ripple = 200mv sine p-p input terminated with 10 w 60 (f = 217hz) 64 (f = 1khz) 55 db (min) electrical characteristics v dd =3v (notes 1, 2) the following specifications apply for the circuit shown in figure 1, unless otherwise specified. limits apply for t a = 25c. symbol parameter conditions lm4901 units (limits) typical limit (note 6) (notes 7, 9) i dd quiescent power supply current v in = 0v, i o = 0a, no load 2 7 ma (max) v in = 0v, i o = 0a, 8 w load 3 9 ma (max) i sd shutdown current v sd =v sd mode (note 8) 0.1 2.0 a (max) v sdih shutdown voltage input high v sd mode =v dd 1.1 v (min) v sdil shutdown voltage input low v sd mode =v dd 0.9 v (max) v sdih shutdown voltage input high v sd mode = gnd 1.3 v (min) v sdil shutdown voltage input low v sd mode = gnd 1.0 v (max) lm4901 www.national.com 3
electrical characteristics v dd =3v (notes 1, 2) the following specifications apply for the circuit shown in figure 1, unless otherwise specified. limits apply for t a = 25c. (continued) symbol parameter conditions lm4901 units (limits) typical limit (note 6) (notes 7, 9) v os output offset voltage 7 50 mv (max) r out resistor output to gnd (note 10) 8.5 9.7 k w (max) 7.0 k w (min) p o output power (8 w ) thd = 1% (max) ;f=1khz 390 mw (4 w ) thd = 1% (max) ;f=1khz 525 mw t wu wake-up time 75 ms (max) thd+n total harmonic distortion+noise p o = 0.25 wrms ; f = 1khz 0.1 % psrr power supply rejection ratio v ripple = 200mv sine p-p input terminated with 10 w 62 (f = 217hz) 68 (f = 1khz) 55 db (min) electrical characteristics v dd = 2.6v (notes 1, 2) the following specifications apply for the circuit shown in figure 1, unless otherwise specified. limits apply for t a = 25c. symbol parameter conditions lm4901 units (limits) typical limit (note 6) (notes 7, 9) i dd quiescent power supply current v in = 0v, i o = 0a, no load 2.0 ma (max) v in = 0v, i o = 0a, 8 w load 3.0 ma (max) i sd shutdown current v sd =v sd mode (note 8) 0.1 a (max) v sdih shutdown voltage input high v sd mode =v dd 1.0 v (min) v sdil shutdown voltage input low v sd mode =v dd 0.9 v (max) v sdih shutdown voltage input high v sd mode = gnd 1.2 v (min) v sdil shutdown voltage input low v sd mode = gnd 1.0 v (max) v os output offset voltage 5 50 mv (max) r out resistor output to gnd (note 10) 8.5 9.7 k w (max) 7.0 k w (min) p o output power ( 8 w ) thd = 1% (max) ;f=1khz 275 mw (4 w ) thd = 1% (max) ;f=1khz 340 t wu wake-up time 70 ms (max) thd+n total harmonic distortion+noise p o = 0.15 wrms ; f = 1khz 0.1 % psrr power supply rejection ratio v ripple = 200mv sine p-p input terminated with 10 w 51 (f = 217hz) 51 (f = 1khz) db (min) note 1: all voltages are measured with respect to the ground pin, unless otherwise specified. note 2: 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 particular 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 3: the maximum power dissipation must be derated at elevated temperatures and is dictated by t jmax , q ja , and the ambient temperature t a . the maximum allowable power dissipation is p dmax =(t jmax t a )/ q ja or the number given in absolute maximum ratings, whichever is lower. for the lm4901, see power derating curves for additional information. note 4: human body model, 100 pf discharged through a 1.5 k w resistor. note 5: machine model, 220 pf240 pf discharged through all pins. note 6: typicals are measured at 25c and represent the parametric norm. note 7: limits are guaranteed to national's aoql (average outgoing quality level). note 8: for micro smd only, shutdown current is measured in a normal room environment. exposure to direct sunlight will increase i sd by a maximum of 2a. note 9: datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. note 10: r rout is measured from the output pin to ground. this value represents the parallel combination of the 10k w output resistors and the two 20k w resistors. lm4901 www.national.com 4
electrical characteristics v dd = 2.6v (notes 1, 2) the following specifications apply for the circuit shown in figure 1, unless otherwise specified. limits apply for t a = 25c. (continued) note 11: if the product is in shutdown mode and v dd exceeds 6v (to a max of 8v v dd ), then most of the excess current will flow through the esd protection circuits. if the source impedance limits the current to a max of 10ma, then the device will be protected. if the device is enabled when v dd is greater than 5.5v and less than 6.5v, no damage will occur, although operation life will be reduced. operation above 6.5v with no current limit will result in permanent damage. note 12: all bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. the LM4901IBL demo board (views featured in the application information section) has two inner layers, one for v dd and one for gnd. the planes each measure 611mils x 661mils (15.52mm x 16.79mm) and aid in spreading heat due to power dissipation within the ic. note 13: maximum power dissipation in the device (p dmax ) occurs at an output power level significantly below full output power. p dmax can be calculated using equation 1 shown in the application information section. it may also be obtained from the power dissipation graphs. note 14: the exposed-dap of the lda10b package should be electrically connected to gnd or an electrically isolated copper area. the lm4901ld demo board (views featured in the application information section) has the exposed-dap connected to gnd with a pcb area of 86.7mils x 585mils (2.02mm x 14.86mm) on the copper top layer and 550mils x 710mils (13.97mm x 18.03mm) on the copper bottom layer. note 15: the thermal performance of the llp package (lm4901ld) when used with the exposed-dap connected to a thermal plane is sufficient for driving 4 w loads. the lm4901ld demo board (views featured in the application information section) can drive 4 w loads at the maximum power dissipation point (1.267w) without thermal shutdown circuitry being activated. the other available packages (msop & micro smd) do not have the thermal performance necessary fo r driving 4 w loads with a 5v supply and are not recommended for this application. external components description ( figure 1 ) components functional description 1. r i inverting input resistance which sets the closed-loop gain in conjunction with r f . this resistor also forms a high pass filter with c i at f c = 1/(2 p r i c i ). 2. c i input coupling capacitor which blocks the dc voltage at the amplifiers input terminals. also creates a highpass filter with r i at f c = 1/(2 p r i c i ). refer to the section, proper selection of external components , for an explanation of how to determine the value of c i . 3. r f feedback resistance which sets the closed-loop gain in conjunction with r i . 4. c s supply bypass capacitor which provides power supply filtering. refer to the power supply bypassing section for information concerning proper placement and selection of the supply bypass capacitor. 5. c b bypass pin capacitor which provides half-supply filtering. refer to the section, proper selection of external components , for information concerning proper placement and selection of c b . typical performance characteristics thd+n vs frequency at v dd =5v,8 w r l , and pwr = 500mw ds200198-30 thd+n vs frequency at v dd =3v,8 w r l , and pwr = 250mw ds200198-31 lm4901 www.national.com 5
typical performance characteristics (continued) thd+n vs frequency at v dd = 2.6v, 8 w r l , and pwr = 150mw ds200198-32 thd+n vs frequency at v dd = 2.6v, 4 w r l , and pwr = 150mw ds200198-33 thd+n vs power out at v dd =5v,8 w r l , 1khz ds200198-34 thd+n vs power out at v dd =3v,8 w r l , 1khz ds200198-83 thd+n vs power out at v dd = 2.6v, 8 w r l , 1khz ds200198-84 thd+n vs power out at v dd = 2.6v, 4 w r l , 1khz ds200198-85 lm4901 www.national.com 6
typical performance characteristics (continued) power supply rejection ratio (psrr) vs frequency at v dd =5v,8 w r l ds200198-86 input terminated with 10 w power supply rejection ratio (psrr) vs frequency at v dd =5v,8 w r l ds200198-87 input floating power supply rejection ratio (psrr) vs frequency at v dd =3v,8 w r l ds200198-88 input terminated with 10 w power supply rejection ratio (psrr) vs frequency at v dd =3v,8 w r l ds200198-89 input floating power supply rejection ratio (psrr) vs frequency at v dd = 2.6v, 8 w r l ds200198-90 input terminated with 10 w power supply rejection ratio (psrr) vs frequency at v dd = 2.6v, 8 w r l ds200198-91 input floating lm4901 www.national.com 7
typical performance characteristics (continued) open loop frequency response, 5v ds200198-92 open loop frequency response, 3v ds200198-93 open loop frequency response, 2.6v ds200198-94 noise floor, 5v, 8 w 80khz bandwidth, input to gnd ds200198-95 power derating curves ds200198-69 ds200198-b5 lm4901 www.national.com 8
typical performance characteristics (continued) ds200198-b6 ds200198-b7 shutdown hysteresis voltage 5v,sdmode=v dd (high) ds200198-a0 shutdown hysteresis voltage 5v, sd mode = gnd (low) ds200198-a1 shutdown hysteresis voltage 3v,sdmode=v dd (high) ds200198-a2 shutdown hysteresis voltage 3v, sd mode = gnd (low) ds200198-a3 lm4901 www.national.com 9
typical performance characteristics (continued) shutdown hysteresis voltage 2.6v, sd mode = v dd (high) ds200198-a4 shutdown hysteresis voltage 2.6v, sd mode = gnd (low) ds200198-a5 ds200198-b8 output power vs supply voltage, 8 w ds200198-a6 output power vs supply voltage, 16 w ds200198-a7 output power vs supply voltage, 32 w ds200198-a8 lm4901 www.national.com 10
typical performance characteristics (continued) frequency response vs input capacitor size ds200198-54 lm4901 www.national.com 11
application information bridge configuration explanation as shown in figure 1 , the lm4901 has two internal opera- tional amplifiers. the first amplifier's gain is externally con- figurable, while the second amplifier is internally fixed in a unity-gain, inverting configuration. the closed-loop gain of the first amplifier is set by selecting the ratio of r f to r i while the second amplifier's gain is fixed by the two internal 20k w resistors. figure 1 shows that the output of amplifier one serves as the input to amplifier two which results in both amplifiers producing signals identical in magnitude, but out of phase by 180. consequently, the differential gain for the ic is a vd = 2 *(r f /r i ) by driving the load differentially through outputs vo1 and vo2, an amplifier configuration commonly referred to as abridged modeo is established. bridged mode operation is different from the classical single-ended amplifier configura- tion where one side of the load is connected to ground. a bridge amplifier design has a few distinct advantages over the single-ended configuration, as it provides differential drive to the load, thus doubling output swing for a specified supply voltage. four times the output power is possible as compared to a single-ended amplifier under the same con- ditions. this increase in attainable output power assumes that the amplifier is not current limited or clipped. in order to choose an amplifier's closed-loop gain without causing ex- cessive clipping, please refer to the audio power amplifier design section. a bridge configuration, such as the one used in lm4901, also creates a second advantage over single-ended amplifi- ers. since the differential outputs, vo1 and vo2, are biased at half-supply, no net dc voltage exists across the load. this eliminates the need for an output coupling capacitor which is required in a single supply, single-ended amplifier configura- tion. without an output coupling capacitor, the half-supply bias across the load would result in both increased internal ic power dissipation and also possible loudspeaker damage. power dissipation power dissipation is a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. a direct consequence of the increased power delivered to the load by a bridge amplifier is an increase in internal power dissipation. since the lm4901 has two opera- tional amplifiers in one package, the maximum internal power dissipation is 4 times that of a single-ended amplifier. the maximum power dissipation for a given application can be derived from the power dissipation graphs or from equa- tion 1. p dmax = 4*(v dd ) 2 /(2 p 2 r l ) (1) it is critical that the maximum junction temperature t jmax of 150c is not exceeded. t jmax can be determined from the power derating curves by using p dmax and the pc board foil area. by adding copper foil, the thermal resistance of the application can be reduced from the free air value of q ja , resulting in higher p dmax values without thermal shutdown protection circuitry being activated. additional copper foil can be added to any of the leads connected to the lm4901. it is especially effective when connected to v dd , gnd, and the output pins. refer to the application information on the lm4901 reference design board for an example of good heat sinking. if t jmax still exceeds 150c, then additional changes must be made. these changes can include re- duced supply voltage, higher load impedance, or reduced ambient temperature. internal power dissipation is a function of output power. refer to the typical performance charac- teristics curves for power dissipation information for differ- ent output powers and output loading. power supply bypassing as with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. the capacitor location on both the bypass and power supply pins should be as close to the device as possible. typical appli- cations employ a 5v regulator with 10 f tantalum or elec- trolytic capacitor and a ceramic bypass capacitor which aid in supply stability. this does not eliminate the need for bypassing the supply nodes of the lm4901. the selection of a bypass capacitor, especially c b , is dependent upon psrr requirements, click and pop performance (as explained in the section, proper selection of external components ), system cost, and size constraints. shutdown function in order to reduce power consumption while not in use, the lm4901 contains shutdown circuitry that is used to turn off the amplifier's bias circuitry. in addition, the lm4901 con- tains a shutdown mode pin, allowing the designer to desig- nate whether the part will be driven into shutdown with a high level logic signal or a low level logic signal. this allows the designer maximum flexibility in device use, as the shutdown mode pin may simply be tied permanently to either v dd or gnd to set the lm4901 as either a 'shutdown-high' device or a 'shutdown-low' device, respectively. the device may then be placed into shutdown mode by toggling the shutdown pin to the same state as the shutdown mode pin. for simplicity's sake, this is called 'shutdown same', as the lm4901 enters shutdown mode whenever the two pins are in the same logic state. the trigger point for either shutdown high or shutdown low is shown as a typical value in the supply current vs shutdown voltage graphs in the typical performance characteristics section. it is best to switch between ground and supply for maximum performance. while the device may be disabled with shutdown voltages in between ground and supply, the idle current may be greater than the typical value of 0.1a. in either case, the shutdown pin should be tied to a definite voltage to avoid unwanted state changes. in many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry, which pro- vides a quick, smooth transition to shutdown. another solu- tion is to use a single-throw switch in conjunction with an external pull-up resistor (or pull-down, depending on shut- down high or low application). this scheme guarantees that the shutdown pin will not float, thus preventing unwanted state changes. proper selection of external components proper selection of external components in applications us- ing integrated power amplifiers is critical to optimize device and system performance. while the lm4901 is tolerant of external component combinations, consideration to compo- nent values must be used to maximize overall system qual- ity. lm4901 www.national.com 12
application information (continued) the lm4901 is unity-gain stable which gives the designer maximum system flexibility. the lm4901 should be used in low gain configurations to minimize thd+n values, and maximize the signal to noise ratio. low gain configurations require large input signals to obtain a given output power. input signals equal to or greater than 1 vrms are available from sources such as audio codecs. please refer to the section, audio power amplifier design , for a more com- plete explanation of proper gain selection. besides gain, one of the major considerations is the closed- loop bandwidth of the amplifier. to a large extent, the band- width is dictated by the choice of external components shown in figure 1 . the input coupling capacitor, c i , forms a first order high pass filter which limits low frequency re- sponse. this value should be chosen based on needed frequency response for a few distinct reasons. selection of input capacitor size large input capacitors are both expensive and space hungry for portable designs. clearly, a certain sized capacitor is needed to couple in low frequencies without severe attenu- ation. but in many cases the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 100 hz to 150 hz. thus, using a large input capacitor may not increase actual system perfor- mance. in addition to system cost and size, click and pop perfor- mance is effected by the size of the input coupling capacitor, c i. 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 the feedback and is apt to create pops upon device enable. thus, by minimizing the capacitor size based on necessary low frequency response, turn-on pops can be minimized. besides minimizing the input capacitor size, careful consid- eration should be paid to the bypass capacitor value. bypass capacitor, c b , is the most critical component to minimize turn-on pops since it determines how fast the lm4901 turns on. the slower the lm4901's outputs ramp to their quiescent dc voltage (nominally 1/2 v dd ), the smaller the turn-on pop. choosing c b equal to 1.0 f along with a small value of c i (in the range of 0.1 f to 0.39 f), should produce a virtually clickless and popless shutdown function. while the device will function properly, (no oscillations or motorboating), with c b equal to 0.1 f, the device will be much more susceptible to turn-on clicks and pops. thus, a value of c b equal to 1.0 f is recommended in all but the most cost sensitive designs. audio power amplifier design a 1w/8 w audio amplifier given: power output 1 wrms load impedance 8 w input level 1 vrms input impedance 20 k w bandwidth 100 hz20 khz 0.25 db a designer must first determine the minimum supply rail to obtain the specified output power. by extrapolating from the output power vs supply voltage graphs in the typical per- formance characteristics section, the supply rail can be easily found. 5v is a standard voltage in most applications, it is chosen for the supply rail. extra supply voltage creates headroom that allows the lm4901 to reproduce peaks in excess of 1w without producing audible distortion. at this time, the de- signer must make sure that the power supply choice along with the output impedance does not violate the conditions explained in the power dissipation section. once the power dissipation equations have been addressed, the required differential gain can be determined from equa- tion 2. (2) r f /r i =a vd /2 from equation 2, the minimum a vd is 2.83; use a vd =3. since the desired input impedance was 20 k w , and with a a vd impedance of 2, a ratio of 1.5:1 of r f to r i results in an allocation of r i =20k w and r f =30k w . the final design step is to address the bandwidth requirements which must be stated as a pair of ?3 db frequency points. five times away from a ?3 db point is 0.17 db down from passband response which is better than the required 0.25 db specified. f l = 100 hz/5 = 20 hz f h =20khz*5=100khz as stated in the external components section, r i in con- junction with c i create a highpass filter. c i 3 1/(2 p *20 k w *20 hz) = 0.397 f; use 0.39 f the high frequency pole is determined by the product of the desired frequency pole, f h , and the differential gain, a vd . with a a vd = 3 and f h = 100 khz, the resulting gbwp = 300khz which is much smaller than the lm4901 gbwp of 2.5mhz. this figure displays that if a designer has a need to design an amplifier with a higher differential gain, the lm4901 can still be used without running into bandwidth limitations. lm4901 www.national.com 13
application information (continued) higher gain audio amplifier the lm4901 is unity-gain stable and requires no external components besides gain-setting resistors, an input coupling capacitor, and proper supply bypassing in the typical appli- cation. however, if a closed-loop differential gain of greater than 10 is required, a feedback capacitor (c4) may be needed as shown in figure 2 to bandwidth limit the amplifier. this feedback capacitor creates a low pass filter that elimi- nates possible high frequency oscillations. care should be taken when calculating the -3db frequency in that an incor- rect combination of r 3 and c 4 will cause rolloff before 20khz. a typical combination of feedback resistor and ca- pacitor that will not produce audio band high frequency rolloff is r 3 = 20k w and c 4 = 25pf. these components result in a -3db point of approximately 320 khz. ds200198-24 figure 2 lm4901 www.national.com 14
application information (continued) differential amplifier configuration for lm4901 ds200198-29 figure 3 lm4901 www.national.com 15
application information (continued) reference design board schematic ds200198-25 figure 4 lm4901 www.national.com 16
application information (continued) lm4901 micro smd board artwork silk screen ds200198-78 top layer ds200198-76 bottom layer ds200198-80 inner layer v dd ds200198-81 inner layer ground ds200198-82 lm4901 www.national.com 17
application information (continued) lm4901 msop demo board artwork silk screen ds200198-75 top layer ds200198-79 bottom layer ds200198-77 lm4901 www.national.com 18
application information (continued) lm4901 llp demo board artwork composite view ds200198-a9 silk screen ds200198-b0 top layer ds200198-b1 bottom layer ds200198-b2 lm4901 www.national.com 19
application information (continued) mono lm4901 reference design boards bill of material part description quantity reference designator lm4901 audio amp 1 u1 tantalum capcitor, 1f 2 c1, c3 ceramic capacitor, 0.39f 1 c2 resistor, 20k w , 1/10w 2 r2, r3 resistor, 100k w , 1/10w 2 r1, r4 jumper header vertical mount 2x1 0.100a spacing 2 j1, j2 pcb layout guidelines this section provides practical guidelines for mixed signal pcb layout that involves various digital/analog power and ground traces. designers should note that these are only 'rule-of-thumb' recommendations and the actual results will depend heavily on the final layout. general mixed signal layout recommendation power and ground circuits for 2 layer mixed signal design, it is important to isolate the digital power and ground trace paths from the analog power and ground trace paths. star trace routing techniques (bring- ing individual traces back to a central point rather than daisy chaining traces together in a serial manner) can have a major impact on low level signal performance. star trace routing refers to using individual traces to feed power and ground to each circuit or even device. this technique will require a greater amount of design time but will not increase the final price of the board. the only extra parts required will be some jumpers. single-point power / ground connections the analog power traces should be connected to the digital traces through a single point (link). a 'pi-filter' can be helpful in minimizing high frequency noise coupling between the analog and digital sections. it is further recommended to put digital and analog power traces over the corresponding digi- tal and analog ground traces to minimize noise coupling. placement of digital and analog components all digital components and high-speed digital signal traces should be located as far away as possible from analog components and circuit traces. avoiding typical design / layout problems avoid ground loops or running digital and analog traces parallel to each other (side-by-side) on the same pcb layer. when traces must cross over each other do it at 90 degrees. running digital and analog traces at 90 degrees to each other from the top to the bottom side as much as possible will minimize capacitive noise coupling and cross talk. lm4901 www.national.com 20
physical dimensions inches (millimeters) unless otherwise noted note: unless otherwise specified. 1. epoxy coating. 2. 63sn/37pb eutectic bump. 3. recommend non-solder mask defined landing pad. 4. pin 1 is established by lower left corner with respect to text orientation pins are numbered counterclockwise. 5. reference jedec registration mo-211, variation bc. 9-bump micro smd order number LM4901IBL, LM4901IBLx ns package number bla09aac lm4901 www.national.com 21
physical dimensions inches (millimeters) unless otherwise noted (continued) msop order number lm4901mm ns package number mub10a lm4901 www.national.com 22
physical dimensions inches (millimeters) unless otherwise noted (continued) life support policy national's products are not authorized for use as critical components in life support devices or systems without the express written approval of the president and general counsel of national semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. a critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. national semiconductor corporation americas email: support@nsc.com national semiconductor europe fax: +49 (0) 180-530 85 86 email: europe.support@nsc.com deutsch tel: +49 (0) 69 9508 6208 english tel: +44 (0) 870 24 0 2171 fran?ais tel: +33 (0) 1 41 91 8790 national semiconductor asia pacific customer response group tel: 65-2544466 fax: 65-2504466 email: ap.support@nsc.com national semiconductor japan ltd. tel: 81-3-5639-7560 fax: 81-3-5639-7507 www.national.com llp order number lm4901ld ns package number lda10b lm4901 1.6 watt audio power amplifier with selectable shutdown logic level national does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and national reserves the righ t at any time without notice to change said circuitry and specifications.

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