TPA751DGN

TPA751 TI | Alldatasheet

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700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 /C0068Fully Specified for 3.3-V and 5-V Operation /C0068Wide Power Supply Compatibility 2.5 V – 5.5 V /C0068Power Supply Rejection at 217 Hz – 84 dB at V DD = 5 V – 81 dB at VDD = 3.3 V /C0068Output Power for RL = 8 Ω – 700 mW at VDD = 5 V – 250 mW at VDD = 3.3 V /C0068Ultralow Supply Current in Shutdown Mode . . . 1.5 nA /C0068Thermal and Short-Circuit Protection /C0068Surface-Mount Packaging – SOIC – PowerPAD MSOP – MicroStar Junior (BGA)

description

The TPA751 is a bridge-tied load (BTL) audio power amplifier developed especially for low-voltage applications where internal speakers are required. Operating with a 3.3-V supply, the TPA751 can deliver 250-mW of continuous power into a BTL 8-Ω load at less than 0.6% THD+N throughout voice band frequencies. Although this device is characterized out to 20 kHz, its operation is optimized for narrower band applications such as wireless communications. The BTL configuration eliminates the need for external coupling capacitors on the output in most applications, which is particularly important for small battery-powered equipment. This device features a shutdown mode for power-sensitive applications with a supply current of 1.5 nA during shutdown. The TPA751 is available in a 3.0 × 3.0 mm MicroStar Junior (BGA), 8-pin SOIC surface-mount package and a surface-mount PowerPAD MSOP. Audio Input Bias Control VDD 700 mW VO + VDD BYPASS IN – VDD /2 C I R I C S C B R F SHUTDOWN VO –8 GND From System Control

3 IN+

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. Copyright  2002, Texas Instruments IncorporatedPRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. SHUTDOWN BYPASS IN+ IN– VO – GND VDD VO + D OR DGN PACKAGE (TOP VIEW) (SIDE VIEW) MicroStar Junior/C0116 (GQS) Package (TOP VIEW) SHUTDOWN VO – BYPASS IN+ IN– GND VDD VO + NOTE: The shaded terminals are used for thermal connections to the ground plane. (E2) (E3) (E4) (E5) (A2) (A3) (A4) (A5) PowerPAD and MicroStar Junior are trademarks of Texas Instruments.

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

MicroStar-Junior (BGA)‡ (GQS) SMALL OUTLINE † (D) MSOP ‡ (DGN) Device TPA751GQS TPA751D TPA751DGN † In the SOIC package, the maximum RMS output power is thermally limited to 350 mW; 700 mW peaks can be driven, as long as the RMS value is less than 350 mW. ‡ The D, DGN, and GQS packages are available taped and reeled. To order a taped and reeled part, add the suffix R to the part number (e.g., TPA751DR). Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION NAME GQS D, DGN I/O DESCRIPTION BYPASS E3 2 I BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be connected to a 0.1-µF to 2.2-µF capacitor when used as an audio amplifier. GND § 7 GND is the ground connection. IN– E5 4 I IN– is the inverting input. IN– is typically used as the audio input terminal. IN+ E4 3 I IN+ is the noninverting input. IN+ is typically tied to the BYPASS terminal for SE input. SHUTDOWN E2 1 I SHUTDOWN places the entire device in shutdown mode when held low (IDD = 1.5 nA). VDD A4 6 VDD is the supply voltage terminal. VO + A5 5 O VO + is the positive BTL output. VO – A2 8 O VO – is the negative BTL output. § A1, A3, A5, B1–B5, C1–C5, D1–D5 are electrical and thermal connections to the ground plane. absolute maximum ratings over operating free-air temperature range (unless otherwise noted)¶ ¶ Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATING TABLE PACKAGE TA = 25°C DERATING FACTOR TA = 70°C TA = 85°C GQS || 1.66 W|| 13.3 mW/°C 1.06 W 866 mW D 725 mW 5.8 mW/°C 464 mW 377 mW DGN 2.14 W# 17.1 mW/°C 1.37 W 1.11 W # See the Texas Instruments document, PowerPAD Thermally Enhanced Package Application Report (SLMA002), for more information on the PowerPAD package. The thermal data was measured on a PCB layout based on the information in the section entitled Texas Instruments Recommended Board for PowerPAD on page 33 of that document. ||See the Texas Instruments document, MicroStar Junior Made Easy Application Brief (SSYA009A) for board layout information on the MicroStar Junior package.

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 3POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 recommended operating conditions MIN MAX UNIT ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply voltage, VDD ÁÁÁ ÁÁÁ 2.5 ÁÁÁÁ ÁÁÁÁ 5.5 ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ High-level input voltage, VIH, (SHUTDOWN ) ÁÁÁ ÁÁÁ 0.9VDD ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Low-level input voltage, VIL, (SHUTDOWN ) ÁÁÁ ÁÁÁ ÁÁÁÁ ÁÁÁÁ 0.1VDD ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Operating free-air temperature, TA ÁÁÁ ÁÁÁ –40 ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁ electrical characteristics at specified free-air temperature, VDD = 3.3 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ |VOS | ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output offset voltage (measured differentially) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = VDD , RL = 8 Ω , RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁÁ ÁÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ VDD = 3.2 V to 3.4 V ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ IDD ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply current ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = VDD , RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ 1.25 ÁÁÁ ÁÁÁ 2.5 ÁÁÁ ÁÁÁ mA ÁÁÁÁ ÁÁÁÁ IDD(SD) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode (see Figure 4) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = 0 V, RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ 1.5 ÁÁÁ ÁÁÁ 1000 ÁÁÁ ÁÁÁ nA ÁÁÁÁ ÁÁÁÁ |IIH| ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN , VDD = 3.3 V, Vi = VDD ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁÁ ÁÁÁÁ |IIL| ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN , VDD = 3.3 V, Vi = 0 V ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 8 Ω PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Output power, See Note 1 ÁÁÁÁÁ ÁÁÁÁÁ THD = 0.2%, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 9 ÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 250 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mW ÁÁÁÁ ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁÁ ÁÁÁÁÁ PO = 250 mW, ÁÁÁÁÁÁ ÁÁÁÁÁÁ f = 200 Hz to 4 kHz, ÁÁÁÁÁ ÁÁÁÁÁ See Figure 7 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.55% ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ BOM ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁÁ ÁÁÁÁÁ AV = –2 V/V, ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 2%, ÁÁÁÁÁ ÁÁÁÁÁ See Figure 7 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Unity-gain bandwidth ÁÁÁÁÁ ÁÁÁÁÁ Open loop, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 15 ÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 1.4 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ MHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁ ÁÁÁÁÁ f = 1 kHz, ÁÁÁÁÁÁ ÁÁÁÁÁÁ C B = 1 µF, ÁÁÁÁÁ ÁÁÁÁÁ See Figure 2 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ Noise output voltage ÁÁÁÁÁ ÁÁÁÁÁ AV = –1V/V, ÁÁÁÁÁÁ ÁÁÁÁÁÁ C B = 0.1 µF, ÁÁÁÁÁ ÁÁÁÁÁ See Figure 19 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µV(rms) NOTE 1: Output power is measured at the output terminals of the device at f = 1 kHz. electrical characteristics at specified free-air temperature, VDD = 5 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ |VOS | ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Output offset voltage (measured differentially) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = VDD , RL = 8 Ω , RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁÁÁÁÁ VDD = 4.9 V to 5.1 V ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ IDD ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply current ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = VDD , RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ 1.45 ÁÁÁ ÁÁÁ 2.5 ÁÁÁ ÁÁÁ mA ÁÁÁÁ ÁÁÁÁ IDD(SD) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode (see Figure 4) ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = 0 V, RF = 10 kΩ ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 1500 ÁÁÁ ÁÁÁ nA ÁÁÁÁ ÁÁÁÁ |IIH| ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN , VDD = 5.5 V, Vi = VDD ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA ÁÁÁÁ ÁÁÁÁ |IIL| ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN , VDD = 5.5 V, Vi = 0 V ÁÁ ÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µA operating characteristics, VDD = 5 V, TA = 25°C, RL = 8 Ω PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ Output power ÁÁÁÁ ÁÁÁÁ THD = 0.5%, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ See Figure 13 ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 700† ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mW ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁ PO = 250 mW, ÁÁÁÁÁÁÁ f = 200 Hz to 4 kHz, ÁÁÁÁ See Figure 11 ÁÁÁ ÁÁÁ 0.5% ÁÁÁ ÁÁÁÁÁÁÁ ÁÁÁÁ BOM ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁ ÁÁÁÁ AV = –2 V/V, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ THD = 2%, ÁÁÁÁ ÁÁÁÁ See Figure 11 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ Unity-gain bandwidth ÁÁÁÁ ÁÁÁÁ Open loop, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ See Figure 16 ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 1.4 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ MHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁ ÁÁÁÁ f = 1 kHz, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ C B = 1 µF, ÁÁÁÁ ÁÁÁÁ See Figure 2 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ Noise output voltage ÁÁÁÁ ÁÁÁÁ AV = –1 V/V, ÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁ C B = 0.1 µF, ÁÁÁÁ ÁÁÁÁ See Figure 20 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ µV(rms) † The GQS and DGN packages, properly mounted, can conduct 700 mW RMS power continuously. The D package, can only conduct 350 mW RMS power continuously, with peaks to 700 mW.

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Figure 1. BTL Mode Test Circuit

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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VDD – Supply Voltage – V OUTPUT POWER vs SUPPLY VOLTAGE 600 400 200 2.5 3.5 3 4 5.5 1000 P 4.5 5 O – Output Power – mW 800 THD+N 1% f = 1 kHz R L = 32 Ω R L = 8 Ω Figure 5 R L – Load Resistance – Ω OUTPUT POWER vs LOAD RESISTANCE 300 200 100 16 32 24 40 64 800 P 48 56 O – Output Power – mW 400 THD+N = 1% f = 1 kHz VDD = 5 V 500 600 VDD = 3.3 V 700 Figure 6

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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f – Frequency – Hz THD+N –Total Harmonic Distortion + Noise – % TOTAL HARMONIC DISTORTION PLUS NOISE vs FREQUENCY AV = –2 V/V VDD = 5 V PO = 700 mW R L = 8 Ω 20 1k 10k 0.01 0.1 20k100 AV = –20 V/V AV = –10 V/V Figure 12 f – Frequency – Hz THD+N –Total Harmonic Distortion + Noise – % TOTAL HARMONIC DISTORTION PLUS NOISE vs FREQUENCY PO = 700 mW VDD = 5 V R L = 8 Ω AV = –2 V/V 20 1k 10k 0.01 0.1 20k100 PO = 50 mW PO = 350 mW Figure 13 PO – Output Power – W THD+N –Total Harmonic Distortion + Noise – % TOTAL HARMONIC DISTORTION PLUS NOISE vs OUTPUT POWER R L = 8 Ω VDD = 5 V f = 1 kHz AV = –2 V/V 0.01 0.1 0.3 0.6 0.9 Figure 14 PO – Output Power – W THD+N –Total Harmonic Distortion + Noise – % TOTAL HARMONIC DISTORTION PLUS NOISE vs OUTPUT POWER f = 20 Hz VDD = 5 V R L = 8 Ω C B = 1 µF AV = –2 V/V 0.01 0.1 1 0.01 0.1 f = 1 kHz f = 10 kHz f = 20 kHz

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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CLOSED-LOOP GAIN AND PHASE vs FREQUENCY –0.5 –1.5 f – Frequency – Hz –0.25 –0.75 –1.25 –1.75 0.5 Closed-Loop Gain – dB 0.25 0.75 130° 120° 140° Phase 150° 160° VDD = 3.3 V R L = 8 Ω PO = 250 mW 170° 180° Gain Phase 101 102 103 104 105 106 Figure 17 CLOSED-LOOP GAIN AND PHASE vs FREQUENCY –0.5 –1.5 f – Frequency – Hz –0.25 –0.75 –1.25 –1.75 0.5 Closed-Loop Gain – dB 0.25 0.75 130° 120° 140° Phase 150° 160° VDD = 5 V R L = 8 Ω PO = 700 m W 170° 180° Gain Phase 101 102 103 104 105 106 Figure 18

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 11POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 TYPICAL CHARACTERISTICS Figure 19 – Output Noise Voltage – VµVn f – Frequency – Hz OUTPUT NOISE VOLTAGE vs FREQUENCY 20 1k 10k 100 20k100 VO BTL VDD = 3.3 V BW = 22 Hz to 22 kHz R L = 8 Ω or 32 Ω AV = –1 V/V VO+ (rms) Figure 20 f – Frequency – Hz OUTPUT NOISE VOLTAGE vs FREQUENCY 20 1k 10k 100 20k100 VDD = 5 V BW = 22 Hz to 22 kHz R L = 8 Ω or 32 Ω AV = –1 V/V VO BTL VO+ – Output Noise Voltage – VµVn (rms) Figure 21 PD – Output Power – mW POWER DISSIPATION vs OUTPUT POWER 6000 150 100 350 PD – Power Dissipation – mW 200 250

300 R L = 8 Ω

R L = 32 Ω VDD = 3.3 V Figure 22 PD – Output Power – mW POWER DISSIPATION vs OUTPUT POWER 400 6000 1000 400 300 100 800 PD – Power Dissipation – mW 500 700 600

200 R L = 32 Ω

VDD = 5 V R L = 8 Ω

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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APPLICATION INFORMATION

Figure 23 shows a linear audio power amplifier (APA) in a BTL configuration. The TPA751 BTL amplifier consists of two linear amplifiers driving both ends of the load. There are several potential benefits to this differential drive configuration, but initially consider power to the load. The differential drive to the speaker means that as one side is slewing up, the other side is slewing down, and vice versa. This, in effect, doubles the voltage swing on the load as compared to a ground referenced load. Plugging 2 × V O(PP) into the power equation, where voltage is squared, yields 4× the output power from the same supply rail and load impedance (see equation 1). Power /C0043 V (rms) R L (1) V (rms)/C0043 V O(PP) 22/C0504 R L 2x VO(PP) VO(PP) –VO(PP) VDD VDD Figure 23. Bridge-Tied Load Configuration

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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BTL amplifier efficiency (continued) Although the voltages and currents for SE and BTL are sinusoidal in the load, currents from the supply are very different between SE and BTL configurations. In an SE application, the current waveform is a half-wave rectified shape, whereas in BTL it is a full-wave rectified waveform. This means RMS conversion factors are different. Keep in mind that for most of the waveform both the push and pull transistors are not on at the same time, which supports the fact that each amplifier in the BTL device only draws current from the supply for half the waveform. The following equations are the basis for calculating amplifier efficiency. Efficiency of a BTL amplifier/C0043 P L P SUP (3) where (4) P L /C0043 V Lrms2 R L , and VLRMS /C0043 V P 2/C0504, therefore, PL /C0043 V P 2R L PL = Power delivered to load PSUP = Power drawn from power supply VLRMS = RMS voltage on BTL load R L = Load resistance VP = Peak voltage on BTL load IDD avg = Average current drawn from the power supply V DD = Power supply voltage ηBTL = Efficiency of a BTL amplifier and P SUP /C0043V DD IDD avg and IDD avg /C00431 /C0112/C0341 /C0112 V P R L sin(t) dt/C00431 /C0112/C0032 V P R L [cos(t)] /C0112 0 /C0043 2V P /C0112R L therefore, P SUP /C0043 2V DD V P /C0112R L substituting PL and PSUP into equation 7, Efficiency of a BTL amplifier/C0043 V P 2R L 2V DD V P /C0112R L /C0043 /C0112V P 4V DD V P /C00432P L R L/C0504 /C0104BTL /C0043 /C01122P L R L/C0504 4V DD where therefore,

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 15POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 Figure 26 is a schematic diagram of a typical handheld audio application circuit, configured for a gain of –10 V/V. Audio Input Bias Control VDD 700 mW VO + VDD BYPASS IN – VDD /2 C I R I 10 kΩ C S 1 µF C B 2.2 µF SHUTDOWN VO – 8 GND From System Control 50 kΩ Figure 26. TPA751 Application Circuit –10 V/V with a differential input. Figure 27. TPA751 Application Circuit With Differential Input

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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application schematics (continued) It is important to note that using the additional RF resistor connected between IN+ and BYPASS causes VDD /2 to shift slightly, which could influence the THD+N performance of the amplifier. Although an additional external operational amplifier could be used to buffer BYPASS from R F, tests in the lab have shown that the THD+N performance is only minimally affected by operating in the fully differential mode as shown in Figure 27. The following sections discuss the selection of the components used in Figures 26 and 27. component selection gain setting resistors, RF and RI The gain for each audio input of the TPA751 is set by resistors RF and RI according to equation 5 for BTL mode. (5)BTL gain/C0043/C00422/C0466 R F R I /C0467 BTL mode operation brings about the factor 2 in the gain equation due to the inverting amplifier mirroring the voltage swing across the load. Given that the TPA751 is a MOS amplifier, the input impedance is very high; consequently input leakage currents are not generally a concern, although noise in the circuit increases as the value of R F increases. In addition, a certain range of RF values is required for proper start-up operation of the amplifier. Taken together 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 in equation 6. (6)Effective impedance/C0043 R FR I R F /C0041R I As an example, consider an input resistance of 10 kΩ and a feedback resistor of 50 kΩ . The BTL gain of the amplifier would be –10 V/V and the effective impedance at the inverting terminal would be 8.3 kΩ , which is well 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 when RF is greater than 50 kΩ . This, in effect, creates a low-pass filter network with the cutoff frequency defined in equation 7. (7) –3 dB fc fc /C00431 2/C0112R F C F For example, if RF is 100 kΩ and CF is 5 pF, then fc is 318 kHz, which is well outside of the audio range.

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 17POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 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 8. (8) –3 dB fc fc /C00431 2/C0112R IC I The value of CI is important to consider, as it directly affects the bass (low frequency) performance of the circuit. Consider the example where RI is 10 kΩ and the specification calls for a flat bass response down to 40 Hz. Equation 8 is reconfigured as equation 9. (9)C I /C00431 2/C0112R Ifc 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 (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. For this reason a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications, as the dc level there is held at V DD /2, which is likely higher than the source dc level. It is important to confirm the capacitor polarity in the application. power supply decoupling, CS The TPA751 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths 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 V DD lead, works best. For filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 10 µF or greater placed near the audio power amplifier is recommended.

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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midrail bypass capacitor, CB The midrail bypass capacitor, CB, is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, CB determines the rate at which the amplifier starts up. 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, which appears as degraded PSRR and THD + N. The capacitor is fed from a 250-kΩ source inside the amplifier. To keep the start-up pop as low as possible, the relationship shown in equation 10 should be maintained. This insures the input capacitor is fully charged before the bypass capacitor is fully charged and the amplifier starts up. (10) /C0466C B /C0032250 kΩ /C0467 /C01181 /C0466R F /C0041R I/C0467C I As an example, consider a circuit where CB is 2.2 µF, CI is 0.47 µF, RF is 50 kΩ , and RI is 10 kΩ . Inserting these values into the equation 10 we get: 18.2/C011835.5 which satisfies the rule. Bypass capacitor, CB, values of 0.1 µF to 2.2 µF ceramic or tantalum low-ESR capacitors are recommended for the best THD and noise performance. using low-ESR capacitors Low-ESR capacitors are recommended throughout this applications section. A real (as opposed to ideal) 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 TPA751 operates 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, as these are considered to be the two most common standard voltages. There are no special considerations for 3.3-V versus 5-V operation with respect to supply bypassing, gain setting, or stability. The most important consideration is that of output power. Each amplifier in TPA751 can produce a maximum voltage swing of V DD – 1 V. This means, for 3.3-V operation, clipping starts to occur when VO(PP) = 2.3 V as opposed to VO(PP) = 4 V at 5 V. The reduced voltage swing subsequently reduces maximum output power into an 8-Ω load before distortion becomes significant. Operation from 3.3-V supplies, as can be shown from the efficiency formula in equation 4, consumes approximately two-thirds the supply power of operation from 5-V supplies for a given output-power level.

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 19POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 headroom and thermal considerations Linear power amplifiers dissipate a significant amount of heat in the package under normal operating conditions. A typical music CD requires 12 dB to 15 dB of dynamic headroom to pass the loudest portions without distortion as compared with the average power output. From the TPA751 data sheet, one can see that when the TPA751 is operating from a 5-V supply into an 8-Ω speaker that 700 mW peaks are available. Converting watts to dB: P dB /C004310Log P W P ref /C004310Log 700 mW 1W /C0043–1.5 dB Subtracting the headroom restriction to obtain the average listening level without distortion yields: –1.5 dB – 15 dB = –16.5 (15 dB headroom) –1.5 dB – 12 dB = –13.5 (12 dB headroom) –1.5 dB – 9 dB = –10.5 (9 dB headroom) –1.5 dB – 6 dB = –7.5 (6 dB headroom) –1.5 dB – 3 dB = –4.5 (3 dB headroom) Converting dB back into watts: P W /C004310PdB /C032410 xP ref = 22 mW (15 dB headroom) = 44 mW (12 dB headroom) = 88 mW (9 dB headroom) = 175 mW (6 dB headroom) = 350 mW (3 dB headroom) This is valuable information to consider when attempting to estimate the heat dissipation requirements for the amplifier system. Comparing the absolute worst case, which is 700 mW of continuous power output with 0 dB of headroom, against 12 dB and 15 dB applications drastically affects maximum ambient temperature ratings for the system. Using the power dissipation curves for a 5-V, 8-Ω system, the internal dissipation in the TPA751 and maximum ambient temperatures is shown in Table 1. Table 1. TPA751 Power Rating, 5-V, 8-Ω , BTL

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

20 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

GQS (S-PBGA-N24) PLASTIC BALL GRID ARRAY M0,05 0,50 0,08 0,50 4201012/A 04/00 2,80 3,20 3,20 2,80 1,00 MAX 0,25 0,35 A Seating Plane 2,00 TYP B C D E 345 2,00 TYP 0,21 0,11 (BOTTOM VIEW) NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. MicroStar Junior configuration

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002 21POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 MECHANICAL DATA D (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE

14 PINS SHOWN

0.228 (5,80) 0.244 (6,20) 0.069 (1,75) MAX 0.010 (0,25) 0.004 (0,10) 0.014 (0,35) 0.020 (0,51) A 0.157 (4,00) 0.150 (3,81) 0.044 (1,12) 0.016 (0,40) Seating Plane 0.010 (0,25) PINS ** 0.008 (0,20) NOM A MIN A MAX DIM Gage Plane 0.189 (4,80) (5,00) 0.197 (8,55) (8,75) 0.337 0.344 (9,80) 0.394 (10,00) 0.386 0.004 (0,10) M0.010 (0,25) 0.050 (1,27) 0°–/C02578° NOTES: D. All linear dimensions are in inches (millimeters). E. This drawing is subject to change without notice. F. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15). G. Falls within JEDEC MS-012

700-mW MONO LOW-VOLTAGE AUDIO POWER AMPLIFIER WITH DIFFERENTIAL INPUTS SLOS336C – DECEMBER 2000 – REVISED OCTOBER 2002

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DGN (S-PDSO-G8) PowerPAD  PLASTIC SMALL-OUTLINE PACKAGE 0,69 0,41 0,25 Thermal Pad (See Note D) 0,15 NOM Gage Plane 4073271/A 04/98 4,98 0,25 3,05 4,782,95 3,05 2,95 0,38 0,15 0,051,07 MAX Seating Plane 0,10 0,65 M0,25 0°–/C02576° NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. Body dimensions include mold flash or protrusions. D. The package thermal performance may be enhanced by attaching an external heat sink to the thermal pad. This pad is electrically and thermally connected to the backside of the die and possibly selected leads. E. Falls within JEDEC MO-187 PowerPAD is a trademark of Texas Instruments.

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