TPA6112A2DGQG4

TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 150-mW STEREO AUDIO POWER AMPLIFIER FEATURES • • • • • • • DGQ PACKAGE (TOP VIEW) 150 mW Stereo Output Differential Inputs PC Power Supply Compatible – Fully Specified for 3.3 V and 5 V Operation – Operation to 2.5 V Pop Reduction Circuitry Internal Mid-Rail Generation Thermal and Short-Circuit Protection Surface-Mount Packaging – PowerPAD™ MSOP VO1 IN1– IN1+ BYPASS GND 1 10 2 9 3 8 4 7 5 6 VDD VO2 IN2– IN2+ SHUTDOWN DESCRIPTION The TPA6112A2 is a stereo audio power amplifier with differential inputs packaged in a 10-pin PowerPAD MSOP package capable of delivering 150 mW of continuous RMS power per channel into 16-Ω loads. Amplifier gain is externally configured by means of two resistors per input channel and does not require external compensation for settings of 1 to 10. TYPICAL APPLICATION CIRCUIT 325 kΩ 325 kΩ VDD 10 VDD Ri C(S) VDD/2 Ri 2 – Right In (Differential) IN1– – + Ci Ri 3 + Ci C(C) IN1+ Rf C(B) VO1 1 4 BYPASS 7 IN2+ Bias Control SHUTDOWN 6 From Shutdown Control Circuit Rf Ri + Left In (Differential) Ci Ri 8 – Ci IN2– + VO2 9 – 5 C(C) Rf 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. PowerPAD is a trademark of Texas Instruments. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2000–2004, Texas Instruments Incorporated TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 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. DESCRIPTION (CONTINUED) THD+N when driving an 16-Ω load from 5 V is 0.03% at 1 kHz, and less than 1% across the audio band of 20 Hz to 20 kHz. For 32-Ω loads, the THD+N is reduced to less than 0.02% at 1 kHz, and is less than 1% across the audio band of 20 Hz to 20 kHz. For 10-kΩ loads, the THD+N performance is 0.005% at 1 kHz, and less than 0.5% across the audio band of 20 Hz to 20 kHz. AVAILABLE OPTIONS PACKAGED DEVICE TA -40°C to 85°C (1) MSOP SYMBOLIZATION MSOP (1) TPA6112A2DGQ TI APD The DGQ package isavailable in left-ended tape and reel only (e.g., TPA6112A2DGQR). Terminal Functions TERMINAL NAME NO I/O DESCRIPTION BYPASS 4 I Tap to voltage divider for internal mid-supply bias supply. Connect to a 0.1 µF to 1 µF low ESR capacitor for best performance. GND 5 I GND is the ground connection. IN1- 2 I IN1- is the negative input for channel 1. IN1+ 3 I IN1+ is the positive input for channel 1. IN2- 8 I IN2- is the negative input for channel 2. IN2+ 7 I IN2+ is the positive input for channel 2. SHUTDOWN 6 I Puts the device in a low quiescent current mode when held high. VDD 10 I VDD is the supply voltage terminal. VO1 1 O VO1 is the audio output for channel 1. VO2 9 O VO2 is the audio output for channel 2. ABSOLUTE MAXIMUM RATINGS over operating free-air temperature (unless otherwise noted (1)) UNITS VDD Supply voltage VI Input voltage 6V -0.3 V to VDD + 0.3 V Continuous total power dissipation internally limited TJ Operating junction temperature range -40°C to 150°C Tstg Storage temperature range -65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds (1) 2 260°C Stresses beyond thoselisted under absolute maximum ratings may cause permanent damage to the device.These are stress ratings only, and functional operation of the device at theseor any other conditions beyond those indicated under recommended operatingconditions is not implied. Exposure to absolute-maximum-rated conditions forextended periods may affect device reliability. TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 DISSIPATION RATING TABLE (1) PACKAGE TA≤ 25°C POWER RATING DERATING FACTOR ABOVE TA = 25°C TA = 70°C POWER RATING TA = 85°C POWER RATING DGQ 2.14 W (1) 17.1 mW/°C 1.37 W 1.11 W Please see the Texas Instrumentsdocument, PowerPAD Thermally EnhancedPackage Application Report (literature number SLMA002), for moreinformation on the PowerPAD package. The thermal data was measured on a PCBlayout based on the information in the section entitledTexas Instruments Recommended Board forPowerPAD on page 33 of the before mentioneddocument. RECOMMENDED OPERATING CONDITIONS MIN MAX UNIT VDD Supply voltage 2.5 5.5 V TA Operating free-air temperature -40 85 °C VIH, (SHUTDOWN) High-level input voltage VIL, (SHUTDOWN) Low-level input voltage 60% x VDD V 25% x VDD V DC ELECTRICAL CHARACTERISTICS At TA = 25°C, VDD = 2.5 V (Unless Otherwise Noted) PARAMETER TEST CONDITIONS MIN TYP VOO Output offset voltage AV = 2 V/V PSRR Power supply rejection ratio VDD = 3.2 V to 3.4 V 83 IDD Supply current SHUTDOWN = 0 V IDD(SD) Supply current in SHUTDOWN mode SHUTDOWN = VDD Zi Input impedance MAX UNIT 15 mV 1.5 3 mA 10 50 µA dB >1 MΩ AC OPERATING CHARACTERISTICS VDD = 3.3 V, TA = 25°C, RL = 16 Ω PARAMETER TEST CONDITIONS MIN TYP MAX Output power (each channel) THD≤ 0.1%, f = 1 kHz THD+N Total harmonic distortion + noise PO = 40 mW, 20 - 20 kHz 0.4% BOM Maximum output power BW G = 10, THD < 5% > 20 Phase margin Open loop 96° Supply ripple rejection ratio f = 1 kHz 71 dB 89 dB Channel/channel output separation f = 1 kHz SNR Signal-to-noise ratio PO = 50 mW, AV = 1 Vn Noise output voltage AV = 1 60 UNIT PO mW kHz 100 dB 11 µV(rms) DC ELECTRICAL CHARACTERISTICS At TA = 25°C, VDD = 5 .5 V (Unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP VOO Output offset voltage AV = 2 V/V PSRR Power supply rejection ratio VDD = 4.9 V to 5.1 V 76 IDD Supply current SHUTDOWN = 0 V IDD(SD) Supply current in SHUTDOWN mode SHUTDOWN = VDD |IIH| High-level input current (SHUTDOWN) |IIL| Low-level input current (SHUTDOWN) Zi Input impedance MAX UNIT 15 mV 1.5 3 mA 60 100 µA VDD = 5.5 V, VI = VDD 1 µA VDD = 5.5 V, VI = 0 V 1 >1 dB µA MΩ 3 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 AC OPERATING CHARACTERISTICS VDD = 5 V, TA = 25°C, RL = 16 Ω PARAMETER TEST CONDITIONS MIN TYP MAX 150 UNIT PO Output power (each channel) THD≤ 0.1%, f = 1 kHz THD+N Total harmonic distortion + noise PO = 100 mW, 20 - 20 kHz 0.6% mW BOM Maximum output power BW G = 10, THD < 5% > 20 Phase margin Open loop 96° Supply ripple rejection ratio f = 1 kHz 61 dB Channel/channel output separation f = 1 kHz 90 dB SNR Signal-to-noise ratio PO = 100 mW, AV = 1 100 dB Vn Noise output voltage AV = 1 11.7 µV(rms) kHz AC OPERATING CHARACTERISTICS VDD = 3.3 V, TA = 25°C, RL = 32 Ω PARAMETER TEST CONDITIONS MIN TYP MAX 40 UNIT PO Output power (each channel) THD≤ 0.1%, f = 1 kHz THD+N Total harmonic distortion + noise PO = 30 mW, 20 - 20 kHz 0.4% mW BOM Maximum output power BW AV = 10, THD < 2% > 20 Phase margin Open loop 96° Supply ripple rejection ratio f = 1 kHz 71 dB Channel/channel output separation f = 1 kHz 95 dB SNR Signal-to-noise ratio PO = 40 mW, AV = 1 Vn Noise output voltage AV = 1 kHz 100 dB 11 µV(rms) AC OPERATING CHARACTERISTICS VDD = 5 V, TA = 25°C, RL = 32 Ω PARAMETER TEST CONDITIONS MIN TYP 90 MAX UNIT PO Output power (each channel) THD≤ 0.1%, f = 1 kHz THD+N Total harmonic distortion + noise PO = 60 mW, 20 - 20 kHz 0.4% mW BOM Maximum output power BW AV = 10, THD < 2% > 20 Phase margin Open loop 97° Supply ripple rejection ratio f = 1 kHz 61 dB 98 dB kHz Channel/channel output separation f = 1 kHz SNR Signal-to-noise ratio PO = 90 mW, AV = 1 100 dB Vn Noise output voltage AV = 1 11.7 µV(rms) 4 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 TYPICAL CHARACTERISTICS Table of Graphs FIGURE THD+N vs Frequency Total harmonic distortion plus noise Vn 1, 3, 5, 6, 7, 9, 11, 13, vs Output power 2, 4, 8, 10, 12, 14 Supply ripple rejection ratio vs Frequency 15, 16 Output noise voltage vs Frequency 17, 18 Crosstalk vs Frequency 19 - 24 Shutdown attenuation vs Frequency 25, 26 Open-loop gain and phase margin vs Frequency 27, 28 Output power vs Load resistance 29, 30, IDD Supply current vs Supply voltage 31 SNR Signal-to-noise ratio vs Voltage gain 32 Power dissipation/amplifier vs Load power 33, 34 TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 1 10 VDD = 3.3 V, PO = 25 mW, CB = 1 µF, RL = 32 Ω, AV = −1 V/V THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 10 0.1 0.01 0.001 20 100 TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 1k 10k 20k 1 VDD = 3.3 V, RL = 32 Ω, AV = −1 V/V, CB = 1 µF 20 kHz 20 Hz 0.1 1 kHz 0.01 0.001 10 50 f − Frequency − Hz PO − Output Power − mW Figure 1. Figure 2. 100 5 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 1 10 VDD = 5 V, PO = 60 mW, CB = 1 µF, RL = 32 Ω, THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 10 AV = −5 V/V AV = −1 V/V AV = −10 V/V 0.1 0.05 0.01 0.001 20 100 TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 1k f − Frequency − Hz 1 kHz 0.01 100 500 Figure 4. TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 10 THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 0.1 Figure 3. VDD = 3.3 V, PO = 100 mW, CB = 1 µF, RL = 10 kΩ, AV = −1 V/V 0.01 100 1k f − Frequency − Hz Figure 5. 6 20 kHz PO − Output Power − mW 0.1 0.001 20 20 Hz 0.001 10 10k 20k 10 1 1 VDD = 5 V, RL = 32 Ω, AV = −1 V/V, CB = 1 µF 10k 20k 1 VDD = 5 V, PO = 100 mW, CB = 1 µF, RL = 10 kΩ AV = −5 V/V AV = −1 V/V 0.1 AV = −10 V/V 0.01 0.001 20 100 1k f − Frequency − Hz Figure 6. 10k 20k TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 10 1 THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 10 VDD = 3.3 V, PO = 60 mW, CB = 1 µF, RL = 8 Ω, AV = −1 V/V 0.1 0.01 0.001 20 100 1k f − Frequency − Hz 1 kHz 0.01 100 Figure 8. TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 500 10 VDD = 5 V, PO = 150 mW, CB = 1 µF, RL = 8 Ω THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 0.1 Figure 7. AV = −5 V/V 0.1 0.001 20 20 kHz PO − Output Power − mW AV = −1 V/V 0.01 20 Hz 0.001 10 10k 20k 10 1 1 VDD = 3.3 V, RL = 8 Ω, AV = −1 V/V, CB = 1 µF AV = −10 V/V 100 1k f − Frequency − Hz Figure 9. 10k 20k 1 VDD = 5 V, RL = 8 Ω, AV = −1 V/V, CB = 1 µF 1 kHz 20 kHz 0.1 0.01 0.001 10 20 Hz 100 PO − Output Power − mW 500 Figure 10. 7 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 10 1 THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 10 VDD = 3.3 V, PO = 40 mW, CB = 1 µF, RL = 16 Ω, AV = −1 V/V 0.1 0.01 0.001 20 100 1k f − Frequency − Hz 500 TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER 10 THD+N − Total Harmonic Distortion + Noise − % THD+N − Total Harmonic Distortion + Noise − % 100 PO − Output Power − mW TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY VDD = 5 V, PO = 100 mW, CB = 1 µF, RL = 16 Ω AV = −5 V/V AV = −10 V/V 100 1k f − Frequency − Hz Figure 13. 8 0.01 Figure 12. 0.1 0.001 20 1 kHz 0.1 Figure 11. AV = −1 V/V 0.01 20 Hz 20 kHz 0.001 10 10k 20k 10 1 1 VDD = 3.3 V, RL =16 Ω, AV = −1 V/V, CB = 1 µF 10k 20k 1 VDD = 5 V, RL = 16 Ω, AV = −1 V/V, CB = 1 µF 20 Hz 20 kHz 1 kHz 0.1 0.01 0.001 10 100 PO − Output Power − mW Figure 14. 500 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 SUPPLY RIPPLE REJECTION RATIO vs FREQUENCY SUPPLY RIPPLE REJECTION RATIO vs FREQUENCY 0 0.1 µF −10 VDD = 3.3 V, RL = 16 Ω, AV = −1 V/V 0.47 µF −20 1 µF −30 −40 −50 −60 −70 −80 Bypass = 1.65 V −90 −100 −110 K SVR − Supply Ripple Rejection Ratio − dB K SVR − Supply Ripple Rejection Ratio − dB 0 −120 VDD = 5 V, RL = 16 Ω, AV = −1 V/V 0.47 µF −20 1 µF −30 −40 −50 −60 −70 −80 Bypass = 2.5 V −90 −100 −110 −120 20 100 1k f − Frequency − Hz 10k 20k 20 100 1k f − Frequency − Hz Figure 15. Figure 16. OUTPUT NOISE VOLTAGE vs FREQUENCY OUTPUT NOISE VOLTAGE vs FREQUENCY 10k 20k 100 VDD = 3.3 V, BW = 10 Hz to 22 kHz RL = 16 Ω AV = −10 V/V AV = −1 V/V 10 1 V n − Output Noise Voltage − µ V(RMS) 100 V n − Output Noise Voltage − µ V(RMS) 0.1 µF −10 AV = −10 V/V AV = −1 V/V 10 VDD = 5 V, BW = 10 Hz to 22 kHz RL = 16 Ω 1 20 100 1k f − Frequency − Hz Figure 17. 10k 20k 20 100 1k f − Frequency − Hz 10k 20k Figure 18. 9 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 CROSSTALK vs FREQUENCY CROSSTALK vs FREQUENCY 0 10 −10 −20 Crosstalk − dB −30 THD+N − Total Harmonic Distortion + Noise − % VDD = 3.3 V, PO = 25 mW, CB = 1 µF, RL = 32 Ω, AV = −1 V/V −40 −50 −60 −70 −80 IN2− to VO1 −90 −100 −110 −120 IN1− to VO2 20 100 1k f − Frequency − Hz 0.01 AV = −10 V/V 100 1k f − Frequency − Hz Figure 20. CROSSTALK vs FREQUENCY CROSSTALK vs FREQUENCY 10k 20k 0 −20 −30 −20 −30 −40 −50 −60 −70 IN2− to VO1 −80 VDD = 5 V, PO = 60 mW, CB = 1 µF, RL = 32 Ω, AV = −1 V/V −10 Crosstalk − dB Crosstalk − dB 0.1 Figure 19. VDD = 3.3 V, PO = 60 mW, CB = 1 µF, RL = 8 Ω, AV = −1 V/V −10 −40 −50 −60 −70 −80 −90 IN2− to VO1 −90 −100 −100 IN1− to VO2 −110 IN1− to VO2 −110 20 100 1k f − Frequency − Hz Figure 21. 10 AV = −5 V/V AV = −1 V/V 0.001 20 10k 20k 0 −120 1 VDD = 5 V, PO = 150 mW, CB = 1 µF, RL = 8 kΩ 10k 20k −120 20 100 1k f − Frequency − Hz Figure 22. 10k 20k TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 CROSSTALK vs FREQUENCY CROSSTALK vs FREQUENCY 0 0 VDD = 5 V, PO = 100 mW, CB = 1 µF, RL = 16 Ω, AV = −1 V/V −10 −20 −20 −30 −40 Crosstalk − dB Crosstalk − dB −30 −50 −60 −70 −80 −50 −60 −70 IN2− to VO1 −90 −100 −100 IN1− to VO2 −110 20 0 −10 100 1k f − Frequency − Hz −120 10k 20k 20 100 1k f − Frequency − Hz Figure 23. Figure 24. SHUTDOWN ATTENUATION vs FREQUENCY SHUTDOWN ATTENUATION vs FREQUENCY 10k 20k 0 VDD = 3.3 V, RL = 16 Ω, CB = 1 µF −10 Shutdown Attenuation − dB −20 −30 −40 −50 −60 −70 −40 −50 −60 −70 −80 −90 −90 100 1k f − Frequency − Hz Figure 25. 10 k 20 k VDD = 5 V, RL = 16 Ω, CB = 1 µF −30 −80 −100 10 IN1− to VO2 −110 −20 Shutdown Attenuation − dB −40 −80 IN2− to VO1 −90 −120 VDD = 5 V, PO = 150 mW, CB = 1 µF, RL = 8 Ω, AV = −1 V/V −10 −100 10 100 1k 10 k 20 k f − Frequency − Hz Figure 26. 11 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 OPEN-LOOP GAIN AND PHASE MARGIN vs FREQUENCY VDD = 3.3 V RL = 10 kΩ 100 180 120 150 100 Gain 120 Phase 90 30 Gain 0 40 −30 20 −60 −90 0 Open-Loop Gain − dB 60 60 150 120 90 80 Φ m − Phase Margin − Deg 80 VDD = 5 V RL = 10 kΩ 60 60 30 Phase 0 40 −30 20 −60 −90 0 −120 −20 −150 −40 1k 10 k 100 k 1M −180 10 M Φm − Phase Margin − Deg 180 120 Open-Loop Gain − dB OPEN-LOOP GAIN AND PHASE MARGIN vs FREQUENCY −120 −20 −150 −40 1k 10 k f − Frequency − Hz 100 k 1M −180 10 M f − Frequency − Hz Figure 27. Figure 28. OUTPUT POWER vs LOAD RESISTANCE OUTPUT POWER vs LOAD RESISTANCE 100 250 VDD = 3.3 V, THD+N = 1%, AV = −1 V/V VDD = 5 V, THD+N = 1%, AV = −1 V/V 200 P − Output Power − mW O P − Output Power − mW O 75 50 25 0 100 50 0 8 12 16 20 24 28 32 36 40 44 45 52 56 60 64 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 RL − Load Resistance − Ω RL − Load Resistance − Ω Figure 29. 12 150 Figure 30. TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 SUPPLY CURRENT vs SUPPLY VOLTAGE SIGNAL-TO-NOISE RATIO vs VOLTAGE GAIN 120 2.5 SNR − Signal-to-Noise Ratio − dB VDD = 5 V I DD − Supply Current − mA 2 1.5 1 0.5 100 80 60 40 20 0 0 0.5 1 1.5 2 2.5 3 3.5 4 VDD − Supply Voltage − V 4.5 5 0 5.5 2 3 4 5 6 7 8 9 10 AV − Voltage Gain − V/V Figure 31. Figure 32. POWER DISSIPATION/AMPLIFIER vs LOAD POWER POWER DISSIPATION/AMPLIFIER vs LOAD POWER 180 80 VDD = 3.3 V VDD = 5 V Power Dissipation/Amplifier − mW 8Ω 70 Power Dissipation/Amplifier − mW 1 60 50 40 16 Ω 30 32 Ω 20 140 120 100 16 Ω 80 60 32 Ω 40 64 Ω 10 8Ω 160 64 Ω 20 0 0 0 20 40 60 80 100 120 140 160 180 Load Power − mW Figure 33. 200 0 20 40 60 80 100 120 140 160 180 200 Load Power − mW Figure 34. 13 TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 APPLICATION INFORMATION f c(highpass)
GAIN SETTING RESISTORS, Rf and Ri The gain for the TPA6112A2 is set by resistors Rf and Ri according to Equation 1. Gain 
 Rf Ri (1) Given that the TPA6112A2 is a MOS amplifier, the input impedance is very high. Consequently input leakage currents are not generally a concern. However, noise in the circuit increases as the value of Rf increases. In addition, a certain range of Rf values is required for proper start-up operation of the amplifier. Considering these factors, it is recommended that the effective impedance seen by the inverting node of the amplifier be set between 5 kΩ and 20 kΩ. The effective impedance is calculated using Equation 2. Effective Impedance  R fR i Rf
Ri (2) For example, if the input resistance is 20 kΩ and the feedback resistor is 20 kΩ, the gain of the amplifier is -1, and the effective impedance at the inverting terminal is 10 kΩ, a value within the recommended range. For high performance applications, metal-film resistors are recommended because they tend to have lower noise levels than carbon resistors. For values of Rf above 50 kΩ, the amplifier tends to become unstable due to a pole formed from Rf and the inherent input capacitance of the MOS input structure. For this reason, a small compensation capacitor of approximately 5 pF should be placed in parallel with Rf. This, in effect, creates a low-pass filter network with the cutoff frequency defined by Equation 3. f c(lowpass)
1 2
R f CF (3) For example, if Rf is 100 kΩ and CF is 5 pF then fc(lowpass) is 318 kHz, which is well outside the audio range. INPUT CAPACITOR, Ci In the typical application, an input capacitor, Ci, is required to allow the amplifier to bias the input signal to the proper dc level for optimum operation. In this case, Ci and Ri form a high-pass filter with the corner frequency determined in Equation 4. 14 1 2
R i Ci (4) The value of Ci directly affects the bass (low frequency) performance of the circuit. Consider the example where Ri is 20 kΩ and the specification calls for a flat bass response down to 20 Hz. Equation 4 is reconfigured as Equation 5. Ci
1 2
R i f c(highpass) (5) In this example, Ci is 0.40 µF, so one would likely choose a value in the range of 0.47 µF to 1 µF. A further consideration for this capacitor is the leakage path from the input source through the input network formed by Ri, Ci, and the feedback resistor (Rf) to the load. This leakage current creates a dc offset voltage at the input to the amplifier that reduces useful headroom, especially in high-gain applications (gain >10). For this reason a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, connect the positive side of the capacitor to the amplifier input in most applications. The dc level there is held at VDD/2—likely higher than the source dc level. It is important to confirm the capacitor polarity in the application. POWER SUPPLY DECOUPLING, C(S) The TPA6112A2 is a high-performance CMOS audio amplifier that requires adequate power-supply decoupling to minimize the output total harmonic distortion (THD). Power-supply decoupling also prevents oscillations when long lead lengths are used between the amplifier and the speaker. The optimum decoupling is achieved by using two capacitors of different types that target different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically 0.1 µF, placed as close as possible to the device VDD lead, works best. For filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near the power amplifier is recommended. TPA6112A2 www.ti.com SLOS342A – DECEMBER 2000 – REVISED SEPTEMBER 2004 MIDRAIL BYPASS CAPACITOR, C(B) The midrail bypass capacitor, C(B), serves several important functions. During start up, C(B) determines the rate at which the amplifier starts up. This helps to push the start-up pop noise into the subaudible range (so low it can not be heard). The second function is to reduce noise produced by the power supply caused by coupling into the output drive signal. This noise is from the midrail generation circuit internal to the amplifier. The capacitor is fed from a 230-kΩ source inside the amplifier. To keep the start-up pop as low as possible, maintain the relationship shown in Equation 6. 1 C(B)
230 kΩ  1 C i R i (6) Consider an example circuit where C(B) is 1 µF, Ci is 1 µF, and Ri is 20 kΩ. Subsitituting these values into the equation 9 results in: 6.25 ≤ 50 which satisfies the rule. Bypass capacitor, C(B), values of 0.1 µF to 1 µF ceramic or tantalum low-ESR capacitors are recommended for the best THD and noise performance. OUTPUT COUPLING CAPACITOR, C(C) In a typical single-supply, single-ended (SE) configuration, an output coupling capacitor (C(C)) is required to block the dc bias at the output of the amplifier, thus preventing dc currents in the load. As with the input coupling capacitor, the output coupling capacitor and impedance of the load form a high-pass filter governed by Equation 7. fc
1 2
R L C(C) (7) The main disadvantage, from a performance standpoint, is that the typically-small load impedance drives the low-frequency corner higher. Large values of C(C) are required to pass low frequencies into the load. Consider the example where a C(C) of 68 µF is chosen and loads vary from 32 Ω to 47 kΩ. Table 1 summarizes the frequency response characteristics of each configuration. Table 1. Common Load Impedances vs LowFrequency Output Characteristics in SE Mode RL C(C) LOWEST FREQUENCY 32 Ω 68 µF 73 Hz 10,000 Ω 68 µF 0.23 Hz 47,000 Ω 68 µF 0.05 Hz As Table 1 indicates, headphone response is adequate, and drive into line level inputs (a home stereo for example) is very good. The output coupling capacitor required in single-supply SE mode also places additional constraints on the selection of other components in the amplifier circuit. With the rules described earlier still valid, add the following relationship: 1 C(B)
230 kΩ  1 C i R i  1 RLC (C) (8) USING LOW-ESR CAPACITORS Low-ESR capacitors are recommended throughout this application. A real capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance, the more the real capacitor behaves like an ideal capacitor. 5-V VERSUS 3.3-V OPERATION The TPA6112A2 was designed for operation over a supply range of 2.5 V to 5.5 V. This data sheet provides full specifications for 5-V and 3.3-V operation, since these are considered to be the two most common supply voltages. There are no special considerations for 3.3-V versus 5-V operation as far as supply bypassing, gain setting, or stability. The most important consideration is that of output power. Each amplifier in theTPA6112A2 can produce a maximum voltage swing of VDD– 1 V. This means, for 3.3-V operation, clipping starts to occur when VO(PP) = 2.3 V as opposed when VO(PP) = 4 V while operating at 5 V. The reduced voltage swing subsequently reduces maximum output power into the load before distortion becomes significant. 15 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) TPA6112A2DGQ ACTIVE HVSSOP DGQ 10 80 RoHS & Green NIPDAU | NIPDAUAG Level-1-260C-UNLIM -40 to 85 APD TPA6112A2DGQR ACTIVE HVSSOP DGQ 10 2500 RoHS & Green NIPDAU | NIPDAUAG Level-1-260C-UNLIM -40 to 85 APD TPA6112A2DGQRG4 ACTIVE HVSSOP DGQ 10 2500 RoHS & Green Level-1-260C-UNLIM -40 to 85 APD NIPDAU (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of