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LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 LME49724 high performance, high fidelity, fully-differential audio operational amplifier check for samples: LME49724 1 features description the LME49724 is an ultra-low distortion, low noise, 2 ? drives 600 ? loads with full output signal high slew rate fully-differential operational amplifier swing optimized and fully specified for high performance, ? optimized for superior audio signal fidelity high fidelity applications. combining advanced ? output short circuit protection leading-edge process technology with state of the art circuit design, the LME49724 fully-differential audio ? psrr and cmrr exceed 100db (typ) operational amplifier delivers superior audio signal ? available in so powerpad package amplification for outstanding audio performance. the LME49724 combines extremely low voltage noise applications density (2.1nv/ hz) with vanishingly low thd+n (0.00003%) to easily satisfy the most demanding ? ultra high quality audio amplification audio applications. to ensure that the most ? high fidelity preamplifiers and active filters challenging loads are driven without compromise, the ? simple single-ended to differential LME49724 has a high slew rate of 18v/ s and an conversion output current capability of 80ma. further, dynamic range is maximized by an output stage that drives ? state of the art d-to-a converters 600 ? loads to 52v p-p while operating on a 15v ? state of the art a-to-d input amplifiers supply voltage. ? professional audio the LME49724's outstanding cmrr (102db), psrr ? high fidelity equalization and crossover (125db), and v os (0.2mv) results in excellent networks operational amplifier dc performance. ? high performance line drivers and receivers the LME49724 has a wide supply range of 2.5v to 18v. over this supply range the LME49724 ? s input circuitry maintains excellent common-mode and power supply rejection, as well as maintaining its low input bias current. the LME49724 is unity gain stable. this fully-differential audio operational amplifier achieves outstanding ac performance while driving complex loads with capacitive values as high as 100pf. table 1. key specifications power supply voltage range 2.5v to 18v r l = 2k ? 0.00003% (typ) thd+n (a v = 1, v out = 3v rms , f in = 1khz) r l = 600 ? 0.00003% (typ) input noise density 2.1nv/ hz (typ) slew rate 18v/ s (typ) gain bandwidth product 50 mhz (typ) open loop gain (r l = 600 ? ) 125 db (typ) input bias current 60na (typ) input offset voltage 0.2mv (typ) dc gain linearity error 0.000009% 1 please be aware that an important notice concerning availability, standard warranty, and use in critical applications of texas instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. 2 all trademarks are the property of their respective owners. production data information is current as of publication date. copyright ? 2008 ? 2013, texas instruments incorporated products conform to specifications per the terms of the texas instruments standard warranty. production processing does not necessarily include testing of all parameters.
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com typical application figure 1. typical application circuit connection diagram figure 2. 8-pin so powerpad see dda0008b package 2 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724 - + - + 8 3 v in- 2 6 1 4 7 5 v in+ v ocm v cc v out+ v out- enable v ee
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 pin descriptions pin name pin function type 1 v in- input pin analog input sets the output dc voltage. internally set by a resistor divider to the 2 v ocm midpoint of the voltages on the v cc and v ee pins. can be forced analog input externally to a different voltage (50k ? input impedance). 3 v cc positive power supply pin. power supply output pin. signal is inverted relative to v in- where the feedback loop is 4 v out+ analog output connected. output pin. signal is inverted relative to v in+ where the feedback loop is 5 v out- analog output connected. 6 v ee negative power supply pin or ground for a single supply configuration. power supply enables the LME49724 when the voltage is greater than 2.35v above the voltage on the v ee pin. disable the LME49724 by connecting to the 7 enable analog input same voltage as on the v ee pin which will reduce current consumption to less than 0.3ma (typ). 8 v in+ input pin analog input exposed pad for improved thermal performance. connect to the same exposed pad potential as the v ee pin or electrically isolate. these devices have limited built-in esd protection. the leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the mos gates. absolute maximum ratings (1) (2) (3) power supply voltage (v s = v cc + |v ee |) 38v storage temperature ? 65 c to 150 c input voltage (v ee ) ? 0.7v to (v cc ) + 0.7v output short circuit continuous power dissipation (4) internally limited esd rating (5) 2000v esd rating (6) 200v junction temperature (t jmax ) 150 c soldering information vapor phase (60sec.) 215 c infrared (60sec.) 220 c thermal resistance ja (mr) 49.6 c/w (1) absolute maximum ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. functional operation of the device and/or non-degradation at the absolute maximum ratings or other conditions beyond those indicated in the recommended operating conditions is not implied. the recommended operating conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. all voltages are measured with respect to the ground pin, unless otherwise specified. (2) the electrical characteristics tables list specifications under the listed recommended operating conditions except as otherwise modified or specified by the electrical characteristics conditions and/or notes. typical specifications are estimations only and are not ensured. (3) if military/aerospace specified devices are required, please contact the texas instruments sales office/distributors for availability and specifications. (4) the maximum power dissipation must be derated at elevated temperatures and is dictated by t jmax , ja , and the ambient temperature, t a . the maximum allowable power dissipation is p dmax = (t jmax - t a ) / ja or the number given in absolute maximum ratings , whichever is lower. (5) human body model, applicable std. jesd22-a114c. (6) machine model, applicable std. jesd22-a115-a. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 3 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com operating ratings (1) (2) temperature range t min t a t max ? 40 c t a +85 c supply voltage range 2.5v v s 18v (1) absolute maximum ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. functional operation of the device and/or non-degradation at the absolute maximum ratings or other conditions beyond those indicated in the recommended operating conditions is not implied. the recommended operating conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. all voltages are measured with respect to the ground pin, unless otherwise specified. (2) the electrical characteristics tables list specifications under the listed recommended operating conditions except as otherwise modified or specified by the electrical characteristics conditions and/or notes. typical specifications are estimations only and are not ensured. electrical characteristics (1) (2) the following specifications apply for v s = 15v, r l = 2k ? , f in = 1khz, and t a = 25 c, unless otherwise specified. LME49724 units symbol parameter conditions (limits) typical (3) limit (4) power supply 2.5v v (min) v s operating power supply 18v v (max) v o = 0v, i o = 0ma i ccq total quiescent current enable = gnd 10 15 ma (max) enable = v ee 0.3 0.5 ma (max) psrr power supply rejection ratio v s = 5v to 15v (5) 125 95 db (min) v enih enable high input voltage device active, t a = 25 c (6) v ee + 2.35 v v enil enable low input voltage device disabled, t a = 25 c (6) v ee + 1.75 v dynamic performance a v = 1, v out = 3v rms thd+n total harmonic distortion + noise r l = 2k ? 0.00003 % r l = 600 ? 0.00003 0.00009 % (max) a v = 1, v out = 3v rms imd intermodulation distortion 0.0005 % two-tone, 60hz & 7khz 4:1 gbwp gain bandwidth product 50 35 mhz (min) v out = 1v p-p , ? 3db fpbw full power bandwidth referenced to output magnitude 13 mhz at f = 1khz sr sew rate r l = 2k ? 18 13 v/ s (min) a v = ? 1, 10v step, c l = 100pf t s settling time 0.2 s settling time to 0.1% ? 10v < v out < 10v, r l = 600 ? 125 100 db (min) a vol open-loop voltage gain ? 10v < v out < 10v, r l = 2k ? 125 db ? 10v < v out < 10v, r l = 10k ? 125 db (1) absolute maximum ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. functional operation of the device and/or non-degradation at the absolute maximum ratings or other conditions beyond those indicated in the recommended operating conditions is not implied. the recommended operating conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. all voltages are measured with respect to the ground pin, unless otherwise specified. (2) the electrical characteristics tables list specifications under the listed recommended operating conditions except as otherwise modified or specified by the electrical characteristics conditions and/or notes. typical specifications are estimations only and are not ensured. (3) typical values represent most likely parametric norms at t a = +25 o c, and at the recommended operation conditions at the time of product characterization and are not ensured. (4) datasheet min/max specification limits are specified by test or statistical analysis. (5) psrr is measured as follows: v os is measured at two supply voltages, 5v and 15v. psrr = | 20log( v os / v s ) |. (6) the enable threshold voltage is determined by v be voltages and will therefore vary with temperature. the typical values represent the most likely parametric norms at t a = +25 c. 4 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 electrical characteristics (1) (2) (continued) the following specifications apply for v s = 15v, r l = 2k ? , f in = 1khz, and t a = 25 c, unless otherwise specified. LME49724 units symbol parameter conditions (limits) typical (3) limit (4) noise v rms equivalent input noise voltage f bw = 20hz to 20khz 0.30 0.64 (max) e n f = 1khz 2.1 nv / hz equivalent input noise density f = 10hz 3.7 (max) input characteristics v os offset voltage 0.2 1 mv (max) average input offset voltage drift vs v os / temp ? 40 c t a 85 c 0.5 v/ c temperature i b input bias current v cm = 0v 60 200 na (max) i os input offset current v cm = 0v 10 65 na (max) input bias current drift vs i os / temp ? 40 c t a 85 c 0.1 na/ c temperature v cc ? 1.5 v (min) v in-cm common-mode input voltage range 14 v ee + 1.5 v (min) cmrr common-mode rejection ? 10v < v cm < 10v 102 95 db (min) differential input impedance 16 k ? z in common-mode input impedance ? 10v < v cm < 10v 500 m ? output characteristics r l = 600 ? 52 50 v p-p (min) v outmax maximum output voltage swing r l = 2k ? 52 v p-p r l = 10k ? 53 v p-p i out-cc instantaneous short circuit current 80 ma f in = 10khz r out output impedance closed-loop 0.01 ? open-loop 23 ? c load capacitive load drive overshoot c l = 100pf 5 % copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 5 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com typical performance characteristics thd+n thd+n vs vs frequency frequency v s = 2.5v, v o = 0.5v rms , differential input v s = 2.5v, v o = 0.8v rms , differential input r l = 600 ? , 2k ? , 10k ? , 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 3. figure 4. thd+n thd+n vs vs frequency frequency v s = 15v, v o = 3v rms , differential input v s = 15v, v o = 10v rms , differential input r l = 600 ? , 2k ? , 10k ? , 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 5. figure 6. thd+n thd+n vs vs frequency frequency v s = 18v, v o = 3v rms , differential input v s = 18v, v o = 10v rms , differential input r l = 600 ? , 2k ? , 10k ? , 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 7. figure 8. 6 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 typical performance characteristics (continued) thd+n thd+n vs vs output voltage output voltage v s = 2.5v, r l = 600 ? , differential input v s = 15v, r l = 600 ? , differential input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 9. figure 10. thd+n thd+n vs vs output voltage output voltage v s = 18v, r l = 600 ? , differential input v s = 2.5v, r l = 2k ? , differential input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 11. figure 12. thd+n thd+n vs vs output voltage output voltage v s = 15v, r l = 2k ? , differential input v s = 18v, r l = 2k ? , differential input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 13. figure 14. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 7 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com typical performance characteristics (continued) thd+n thd+n vs vs output voltage output voltage v s = 2.5v, r l = 10k ? , differential input v s = 15v, r l = 10k ? , differential input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 15. figure 16. thd+n thd+n vs vs output voltage frequency v s = 18v, r l = 10k ? , differential input v s = 2.5v, v o = 0.5v rms , single-ended input f = 20hz, 1khz, 20khz, 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 17. figure 18. thd+n thd+n vs vs frequency frequency v s = 2.5v, v o = 0.8v rms , single-ended input v s = 15v, v o = 3v rms , single-ended input r l = 600 ? , 2k ? , 10k ? , 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 19. figure 20. 8 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 typical performance characteristics (continued) thd+n thd+n vs vs frequency frequency v s = 15v, v o = 5v rms , single-ended input v s = 18v, v o = 3v rms , single-ended input r l = 600 ? , 2k ? , 10k ? , 80khz bw r l = 600 ? , 2k ? , 10k ? , 80khz bw figure 21. figure 22. thd+n thd+n vs vs frequency output voltage v s = 18v, v o = 5v rms , single-ended input v s = 2.5v, r l = 600 ? , single-ended input r l = 600 ? , 2k ? , 10k ? , 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 23. figure 24. thd+n thd+n vs vs output voltage output voltage v s = 15v, r l = 600 ? , single-ended input v s = 18v, r l = 600 ? , single-ended input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 25. figure 26. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 9 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com typical performance characteristics (continued) thd+n thd+n vs vs output voltage output voltage v s = 2.5v, r l = 2k ? , single-ended input v s = 15v, r l = 2k ? , single-ended input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 27. figure 28. thd+n thd+n vs vs output voltage output voltage v s = 18v, r l = 2k ? , single-ended input v s = 2.5v, r l = 10k ? , single-ended input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 29. figure 30. thd+n thd+n vs vs output voltage output voltage v s = 15v, r l = 10k ? , single-ended input v s = 18v, r l = 10k ? , single-ended input f = 20hz, 1khz, 20khz, 80khz bw f = 20hz, 1khz, 20khz, 80khz bw figure 31. figure 32. 10 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 typical performance characteristics (continued) psrr psrr vs vs frequency frequency v s = 2.5v, r l = 600 ? , inputs to gnd v s = 15v, r l = 600 ? , inputs to gnd v ripple = 200mv p-p , 80khz bw v ripple = 200mv p-p , 80khz bw figure 33. figure 34. psrr psrr vs vs frequency frequency v s = 18v, r l = 600 ? , inputs to gnd v s = 2.5v, r l = 2k ? , inputs to gnd v ripple = 200mv p-p , 80khz bw v ripple = 200mv p-p , 80khz bw figure 35. figure 36. psrr psrr vs vs frequency frequency v s = 15v, r l = 2k ? , inputs to gnd v s = 18v, r l = 2k ? , inputs to gnd v ripple = 200mv p-p , 80khz bw v ripple = 200mv p-p , 80khz bw figure 37. figure 38. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 11 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com typical performance characteristics (continued) psrr psrr vs vs frequency frequency v s = 2.5v, r l = 10k ? , inputs to gnd v s = 15v, r l = 10k ? , inputs to gnd v ripple = 200mv p-p , 80khz bw v ripple = 200mv p-p , 80khz bw figure 39. figure 40. psrr cmrr vs vs frequency frequency v s = 18v, r l = 10k ? , inputs to gnd v s = 2.5v, v cmrr = 1v p-p v ripple = 200mv p-p , 80khz bw r l = 600 ? , 2k ? , 10k ? figure 41. figure 42. cmrr cmrr vs vs frequency frequency v s = 15v, v cmrr = 1v p-p v s = 18v, v cmrr = 1v p-p r l = 600 ? , 2k ? , 10k ? r l = 600 ? , 2k ? , 10k ? figure 43. figure 44. 12 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 typical performance characteristics (continued) output voltage output voltage vs vs load resistance load resistance v s = 2.5v, r l = 500 ? ? 10k ? v s = 15v, r l = 500 ? ? 10k ? thd+n 1%, 80khz bw thd+n 1%, 80khz bw figure 45. figure 46. output voltage output voltage vs vs load resistance supply voltage v s = 18v, r l = 500 ? ? 10k ? r l = 600 ? , 2k ? , 10k ? , thd+n 1% thd+n 1%, 80khz bw 80khz bw figure 47. figure 48. supply current vs supply voltage v in = 0v, r l = no load figure 49. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 13 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com application information general operation the LME49724 is a fully differential amplifier with an integrated common-mode reference input (v ocm ). fully differential amplification provides increased noise immunity, high dynamic range, and reduced harmonic distortion products. differential amplifiers typically have high cmrr providing improved immunity from noise. when input, output, and supply line trace pairs are routed together, noise pick up is common and easily rejected by the LME49724. cmrr performance is directly proportional to the tolerance and matching of the gain configuring resistors. with 0.1% tolerance resistors the worst case cmrr performance will be about 60db (20log(0.001)). a differential output has a higher dynamic range than a single-ended output because of the doubling of output voltage. the dynamic range is increased by 6db as a result of the outputs being equal in magnitude but opposite in phase. as an example, a single-ended output with a 1v pp signal will be two 1v pp signals with a differential output. the increase is 20log(2) = 6db. differential amplifiers are ideal for low voltage applications because of the increase in signal amplitude relative to a single-ended amplifier and the resulting improvement in snr. differential amplifiers can also have reduced even order harmonics, all conditions equal, when compared to a single-ended amplifier. the differential output causes even harmonics to cancel between the two inverted outputs leaving only the odd harmonics. in practice even harmonics do not cancel completely, however there still is a reduction in total harmonic distortion. output common-mode voltage (v ocm pin) the output common-mode voltage is the dc voltage on each output. the output common-mode voltage is set by the v ocm pin. the v ocm pin can be driven by a low impedance source. if no voltage is applied to the v ocm pin, the dc common-mode output voltage will be set by the internal resistor divider to the midpoint of the voltages on the v cc and v ee pins. the input impedance of the v ocm pin is 50k ? . the v ocm pin can be driven up to v cc - 1.5v and v ee + 1.5v. the v ocm pin should be bypassed to ground with a 0.1 f to 1 f capacitor. the v ocm pin should be connected to ground when the desired output common-mode voltage is ground reference. the value of the external capacitor has an effect on the psrr performance of the LME49724. with the v ocm pin only bypassed with a low value capacitor, the psrr performance of the LME49724 will be reduced, especially at low audio frequencies. for best psrr performance, the v ocm pin should be connected to stable, clean reference. increasing the value of the bypass capacitor on the v ocm pin will also improve psrr performance. enable function the LME49724 can be placed into standby mode to reduce system current consumption by driving the enable pin below v ee + 1.75v. the LME49724 is active when the voltage on the enable pin is above v ee + 2.35v. the enable pin should not be left floating. for best performance under all conditions, drive the enable pin to the v ee pin voltage to enter standby mode and to ground for active operation when operating from split supplies. when operating from a single supply, drive the enable pin to ground for standby mode and to v cc for active mode. 14 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 fully differential operation the LME49724 performs best in a fully differential configuration. the circuit shown in figure 50 is the typical fully differential configuration. figure 50. fully differential configuration the closed-loop gain is shown in equation 1 below. a v = r f / r i (v/v) where ? r f1 = r f2 ? r i1 = r i2 ? using low value resistors will give the lowest noise performance (1) single-ended to differential conversion for many applications, it is required to convert a single-ended signal to a differential signal. the LME49724 can be used for a high performance, simple single-to-differential converter. figure 51 shows the typical single-to- differential converter circuit configuration. figure 51. single-ended input to differential output copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 15 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com single supply operation the LME49724 can be operated from a single power supply, as shown in figure 52 . the supply voltage range is limited to a minimum of 5v and a maximum of 36v. the common-mode output dc voltage will be set to the midpoint of the supply voltage. the v ocm pin can be used to adjust the common-mode output dc voltage on the outputs, as described previously, if the supply voltage midpoint is not the desired dc voltage. figure 52. single supply configuration driving a capacitive load the LME49724 is a high speed op amp with excellent phase margin and stability. capacitive loads up to 100pf will cause little change in the phase characteristics of the amplifiers and are therefore allowable. capacitive loads greater than 100pf must be isolated from the output. the most straightforward way to do this is to put a resistor in series with the output. this resistor will also prevent excess power dissipation if the output is accidentally shorted. thermal pcb design the LME49724's high operating supply voltage along with its high output current capability can result in significant power dissipation. for this reason the LME49724 is provided in the exposed dap so powerpad package for improved thermal dissipation performance compared to other surface mount packages. the exposed pad is designed to be soldered to a copper plane on the pcb which then acts as a heat sink. the thermal plane can be on any layer by using multiple thermal vias under and outside the ic package. the vias under the ic should have solder mask openings for the entire pad under the ic on the top layer but cover the vias on the bottom layer. this method prevents solder from being pulled away from the thermal vias during the reflow process resulting in optimum thermal conductivity. heat radiation from the pcb plane area is best accomplished when the thermal plane is on the top or bottom copper layers. the LME49724 should always be soldered down to a copper pad on the pcb for both optimum thermal performance as well as mechanical stability. the exposed pad is for heat transfer and the thermal plane should either be electrically isolated or connected to the same potential as the v ee pin. for high frequency applications (f > 1mhz) or lower impedance loads, the pad should be connected to a plane that is connected to the v ee potential. 16 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 supply bypassing the LME49724 should have its supply leads bypassed with low-inductance capacitors such as leadless surface mount (smt) capacitors located as close as possible to the supply pins. it is recommended that a 10 f tantalum or electrolytic capacitor be placed in parallel with a 0.1 f ceramic or film type capacitor on each supply pin. these capacitors should be star routed with a dedicated ground return plane or large trace for best thd performance. placing capacitors too far from the power supply pins, especially with thin connecting traces, can lead to excessive inductance, resulting in degraded high-frequency bypassing. poor high-frequency bypassing can result in circuit instabilities. when using high bandwidth power supplies, the value and number of supply bypass capacitors should be reduced for optimal power supply performance. balance cable driver with high peak-to-peak differential output voltage and plenty of low distortion drive current, the LME49724 makes an excellent balanced cable driver. combining the single-to-differential configuration with a balanced cable driver results in a high performance single-ended input to balanced line driver solution. although the LME49724 can drive capacitive loads up to 100pf, cable loads exceeding 100pf can cause instability. for such applications, series resistors are needed on the outputs before the capacitive load. analog-to-digital converter (adc) application figure 53 is a typical fully differential application circuit for driving an analog-to-digital converter (adc). the additional components of r 5 , r 6 , and c 7 are optional components and are for stability and proper adc sampling. adc's commonly use switched capacitor circuitry at the input. when the adc samples the signal the current momentarily increases and may disturb the signal integrity at the sample point causing a signal glitch. component c 7 is significantly larger than the input capacitance of a typical adc and acts as a charge reservoir greatly reducing the effect of the signal sample by the adc. resistors r 5 and r 6 decouple the capacitive load, c 7 , for stability. the values shown are general values. specific values should be optimized for the particular adc loading requirements. the output reference voltage from the adc can be used to drive the v ocm pin to set the common-mode dc voltage on the outputs of the LME49724. a buffer may be needed to drive the LME49724's v ocm pin if the adc cannot drive the 50k ? input impedance of the v ocm pin. in order to minimize circuit distortion when using capacitors in the signal path, the capacitors should be comprised of either npo ceramic, polystyrene, polypropylene or mica composition. other types of capacitors may provide a reduced distortion performance but for a cost improvement, so capacitor selection is dependent upon design requirements. the performance/cost tradeoff for a specific application is left up to the user. copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 17 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com * value is application and converted dependent. figure 53. typical analog-to-digital converter circuit distortion measurements the vanishing low residual distortion produced by the LME49724 is below the capabilities of commercially available equipment. this makes distortion measurements more difficult than simply connecting a distortion meter to the amplifier ? s inputs and outputs. the solution, however, is quite simple: an additional resistor. adding this resistor extends the resolution of the distortion measurement equipment. the LME49724 ? s low residual distortion is an input referred internal error. as shown in figure 54 , adding a resistor connected between the amplifier ? s inputs changes the amplifier ? s noise gain. the result is that the error signal (distortion) is increased. although the amplifier ? s closed-loop gain is unaltered, the feedback available to correct distortion errors is reduced, which means that measurement resolution increases. to ensure minimum effects on distortion measurements, keep the value of r 5 low. the distortion reading on the audio analyzer must be divided by a factor of (r 3 + r 4 )/r 5 , where r 1 = r 2 and r 3 = r 4 , to get the actual measured distortion of the device under test. the values used for the LME49724 measurements were r 1 , r 2 , r 3 , r 4 = 1k ? and r 5 = 20 ? . this technique is verified by duplicating the measurements with high closed-loop gain and/or making the measurements at high frequencies. doing so produces distortion components that are within the measurement equipment ? s capabilities. 18 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 figure 54. thd+n and imd distortion test circuit performance variations the LME49724 has excellent performance with little variation across different supply voltages, load impedances, and input configuration (single-ended or differential). inspection of the thd+n vs frequency and thd+n vs output voltage performance graphs (see typical performance characteristics reveals only minimal differences with different load values. figure 55 and figure 56 below show the performance across different supply voltages with the same output signal level and load. figure 55 has plots at 5v, 12v, 15v, and 18v with a 3v rms output while figure 56 has plots at 12v, 15v, and 18v with a 10v rms output. both figures use a 600 ? load. the performance for each different supply voltage under the same conditions is so similar it is nearly impossible to discern the different plots lines. figure 55. thd+n vs frequency with r l = 600 ? v out = 3v rms , differential input, 80khz bw v s = 5v, 12v, 15v, and 18v copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 19 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com figure 56. thd+n vs frequency with r l = 600 ? v out = 10v rms , differential input, 80khz bw v s = 12v, 15v, and 18v whether the input configuration is single-ended or differential has only a minimal affect on thd+n performance at higher audio frequencies or higher signal levels. for easy comparison, figure 57 and figure 58 are a combination of the performance graphs found in typical performance characteristics . figure 57. thd+n vs frequency with r l = 10k ? v out = 3v rms , v s = 15v, 80khz bw single-ended and differential input 20 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 figure 58. thd+n vs output voltage with r l = 10k ? f = 20hz, 1khz, 20khz, v s = 15v, 80khz bw single-ended and differential input power supply rejection ratio does not vary with load value nor supply voltage. for easy comparison, figure 59 and figure 60 below are created by combining performance graphs found in typical performance characteristics . figure 59. psrr vs frequency with r l = 600 ? v s = 2.5v, 15v, and 18v, 80khz bw copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 21 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com figure 60. psrr vs frequency with v s = 15v r l = 600 ? , 2k ? , and 10k ? , 80khz bw although supply current may not be a critical specification for many applications, there is also no real variation in supply current with no load or with a 600 ? load. this is a result of the extremely low offset voltage, typically less than 1mv. figure 61 shows the supply current under the two conditions with no real difference discernable. figure 61. supply current vs supply voltage r l = no load and 600 ? 22 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
LME49724 www.ti.com snas438a ? november 2008 ? revised april 2013 demo board schematic figure 62. demonstration board circuit build of materials table 2. reference demo board bill of materials designator value tolerance part description comment r 1 , r 2 , r 3 , r 4 1k ? 1% 1/8w, 0603 resistor r 5 , r 6 40.2 ? 1% 1/8w, 0603 resistor c 1 , c 2 1000pf 10% 0603, npo ceramic capacitor, 50v c 3 , c 4 , c 8 , c 9 0.1 f ? 20%, +80% 0603, y5v ceramic capacitor, 25v c 5 , c 6 10 f 20% size c (6032), tantalum capacitor, 25v c 7 2700pf 10% 0805, npo ceramic capacitor, 50v u 1 LME49724mr j 1 , j 2 , j 3 , j 4 sma coaxial connector inputs & outputs j 5 0.100" 1x3 header, vertical mount v dd , v ee , gnd j 6 , j 7 , j 8 , j 9 , j 10 , inputs, outputs, v ocm , 0.100" 1x2 header, vertical mount j 11 enable copyright ? 2008 ? 2013, texas instruments incorporated submit documentation feedback 23 product folder links: LME49724
LME49724 snas438a ? november 2008 ? revised april 2013 www.ti.com revision history rev date description 1.0 11/12/08 initial release. a 04/04/13 changed layout of national data sheet to ti format. 24 submit documentation feedback copyright ? 2008 ? 2013, texas instruments incorporated product folder links: LME49724
package option addendum www.ti.com 30-jun-2016 addendum-page 1 packaging information orderable device status (1) package type package drawing pins package qty eco plan (2) lead/ball finish (6) msl peak temp (3) op temp (c) device marking (4/5) samples LME49724mr/nopb active so powerpad dda 8 95 green (rohs & no sb/br) cu sn level-3-260c-168 hr -40 to 85 l49724 mr LME49724mrx/nopb active so powerpad dda 8 2500 green (rohs & no sb/br) cu sn level-3-260c-168 hr -40 to 85 l49724 mr (1) the marketing status values are defined as follows: active: product device recommended for new designs. lifebuy: ti has announced that the device will be discontinued, and a lifetime-buy period is in effect. nrnd: not recommended for new designs. device is in production to support existing customers, but ti does not recommend using this part in a new design. preview: device has been announced but is not in production. samples may or may not be available. obsolete: ti has discontinued the production of the device. (2) eco plan - the planned eco-friendly classification: pb-free (rohs), pb-free (rohs exempt), or green (rohs & no sb/br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. tbd: the pb-free/green conversion plan has not been defined. pb-free (rohs): ti's terms "lead-free" or "pb-free" mean semiconductor products that are compatible with the current rohs requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. where designed to be soldered at high temperatures, ti pb-free products are suitable for use in specified lead-free processes. pb-free (rohs exempt): this component has a rohs exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. the component is otherwise considered pb-free (rohs compatible) as defined above. green (rohs & no sb/br): ti defines "green" to mean pb-free (rohs compatible), and free of bromine (br) and antimony (sb) based flame retardants (br or sb do not exceed 0.1% by weight in homogeneous material) (3) msl, peak temp. - the moisture sensitivity level rating according to the jedec industry standard classifications, and peak solder temperature. (4) there may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) multiple device markings will be inside parentheses. only one device marking contained in parentheses and separated by a "~" will appear on a device. if a line is indented then it is a continuation of the previous line and the two combined represent the entire device marking for that device. (6) lead/ball finish - orderable devices may have multiple material finish options. finish options are separated by a vertical ruled line. lead/ball finish values may wrap to two lines if the finish value exceeds the maximum column width. important information and disclaimer: the information provided on this page represents ti's knowledge and belief as of the date that it is provided. ti bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. efforts are underway to better integrate information from third parties. ti has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ti and ti suppliers consider certain information to be proprietary, and thus cas numbers and other limited information may not be available for release.
package option addendum www.ti.com 30-jun-2016 addendum-page 2 in no event shall ti's liability arising out of such information exceed the total purchase price of the ti part(s) at issue in this document sold by ti to customer on an annual basis.
tape and reel information *all dimensions are nominal device package type package drawing pins spq reel diameter (mm) reel width w1 (mm) a0 (mm) b0 (mm) k0 (mm) p1 (mm) w (mm) pin1 quadrant LME49724mrx/nopb so power pad dda 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 q1 package materials information www.ti.com 8-apr-2013 pack materials-page 1
*all dimensions are nominal device package type package drawing pins spq length (mm) width (mm) height (mm) LME49724mrx/nopb so powerpad dda 8 2500 367.0 367.0 35.0 package materials information www.ti.com 8-apr-2013 pack materials-page 2

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