TPA301DGN

TPA301 TI | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 22

Technical content

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 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 /C0068Output Power for RL = 8 W – 350 mW at VDD = 5 V, BTL – 250 mW at VDD = 3.3 V, BTL /C0068Ultra-Low Quiescent Current in Shutdown Mode . . . 0.15 mA /C0068Thermal and Short-Circuit Protection /C0068Surface-Mount Packaging – SOIC – PowerPAD MSOP

description

The TPA301 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 TPA301 can deliver 250-mW of continuous power into a BTL 8-W load at less than 1% THD+N throughout voice band frequencies. Although this device is characterized out to 20 kHz, its operation was optimized for narrower band applications such as cellular 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 quiescent current of 0.15 mA during shutdown. The TPA301 is available in an 8-pin SOIC surface-mount package and the surface-mount PowerPAD MSOP, which reduces board space by 50% and height by 40%. Audio Input Bias Control VDD 350 mW VO + VDD BYPASS IN – VDD /2 C I R I C S 1 mF C B 0.1 mF 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  2000, 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) PowerPAD is a trademark of Texas Instruments.

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

2 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

MSOPTA SMALL OUTLINE † (D) MSOP † (DGN) MSOP Symbolization –40°C to 85°C TPA301D TPA301DGN AAA † The D and DGN packages are available taped and reeled. To order a taped and reeled part, add the suffix R to the part number (e.g., TPA301DR). Terminal Functions TERMINAL I/O DESCRIPTION NAME NO. I/O DESCRIPTION BYPASS 2 I BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be connected to a 0.1-mF to 1-mF capacitor when used as an audio amplifier. GND 7 GND is the ground connection. IN– 4 I IN– is the inverting input. IN– is typically used as the audio input terminal. IN+ 3 I IN+ is the noninverting input. IN+ is typically tied to the BYPASS terminal. SHUTDOWN 1 I SHUTDOWN places the entire device in shutdown mode when held high (IDD < 1 mA). VDD 6 VDD is the supply voltage terminal. VO + 5 O VO + is the positive BTL output. VO – 8 O VO – is the negative BTL output. 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 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 § Please see the Texas Instruments document, PowerPAD Thermally Enhanced Package Application Report (literature number 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 the before mentioned document. recommended operating conditions MIN MAX UNIT ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply voltage, VDD ÁÁÁ ÁÁÁ 2.5 ÁÁÁ ÁÁÁ 5.5 ÁÁÁ ÁÁÁ V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Operating free-air temperature, TA ÁÁÁ ÁÁÁ –40 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 3POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 electrical characteristics at specified free-air temperature, VDD = 3.3 V, TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁ ÁÁÁ VOD ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Differential output voltage ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Note 1 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁ ÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁ ÁÁÁÁÁÁ VDD = 3.2 V to 3.4 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁ ÁÁÁ IDD(q) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current (see Figure 3) ÁÁÁÁÁÁ ÁÁÁÁÁÁ BTL mode ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.7 ÁÁÁ ÁÁÁ 1.5 ÁÁÁ ÁÁÁ mA ÁÁÁ ÁÁÁ IDD(sd) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode (see Figure 4) ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.15 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mA NOTE 1: At 3 V < VDD < 5 V the dc output voltage is approximately VDD /2. operating characteristics, VDD = 3.3 V, TA = 25°C, RL = 8 W PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Output power, see Note 2 ÁÁÁÁÁ ÁÁÁÁÁ THD = 0.5%, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 9 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 250 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mW ÁÁÁÁ Á ÁÁ Á ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Á ÁÁÁÁÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁÁ Á ÁÁÁ Á ÁÁÁÁÁ PO = 250 mW, Gain = 2, ÁÁÁÁÁÁ Á ÁÁÁÁ Á ÁÁÁÁÁÁ f = 20 Hz to 4 kHz, See Figure 7 ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ 1.3% ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁÁ ÁÁÁÁÁ Gain = 2, See Figure 7 ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 3%, ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Unity-gain bandwidth ÁÁÁÁÁ ÁÁÁÁÁ Open Loop, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 15 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 1.4 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ MHz ÁÁÁÁ Á ÁÁ Á ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Á ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁ Á ÁÁÁ Á ÁÁÁÁÁ f = 1 kHz, See Figure 2 ÁÁÁÁÁÁ Á ÁÁÁÁ Á ÁÁÁÁÁÁ C B = 1 mF, ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Noise output voltage ÁÁÁÁÁ ÁÁÁÁÁ Gain = 1, R L = 32 W , ÁÁÁÁÁÁ ÁÁÁÁÁÁ C B = 0.1 mF, See Figure 19 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV(rms) NOTE 2: 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 ÁÁÁ VOD ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Differential output voltage ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV ÁÁÁ ÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁ ÁÁÁÁÁÁ VDD = 4.9 V to 5.1 V ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ dB ÁÁÁ ÁÁÁ IDD(q) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Quiescent current (see Figure 3) ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.7 ÁÁÁ ÁÁÁ 1.5 ÁÁÁ ÁÁÁ mA ÁÁÁ ÁÁÁ IDD(sd) ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Quiescent current, shutdown mode (see Figure 4) ÁÁÁÁÁÁ ÁÁÁÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 0.15 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mA operating characteristics, VDD = 5 V, TA = 25°C, RL = 8 W PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Output power ÁÁÁÁÁ ÁÁÁÁÁ THD = 0.5%, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 13 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 700 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mW ÁÁÁÁ Á ÁÁ Á ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Á ÁÁÁÁÁÁÁÁÁÁÁÁÁ Total harmonic distortion plus noise ÁÁÁÁÁ Á ÁÁÁ Á ÁÁÁÁÁ PO = 250 mW, Gain = 2, ÁÁÁÁÁÁ Á ÁÁÁÁ Á ÁÁÁÁÁÁ f = 20 Hz to 4 kHz, See Figure 11 ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth ÁÁÁÁÁ ÁÁÁÁÁ Gain = 2, See Figure 11 ÁÁÁÁÁÁ ÁÁÁÁÁÁ THD = 2%, ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ kHz ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Unity-gain bandwidth ÁÁÁÁÁ ÁÁÁÁÁ Open Loop, ÁÁÁÁÁÁ ÁÁÁÁÁÁ See Figure 16 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ 1.4 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ MHz ÁÁÁÁ Á ÁÁ Á ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Á ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁ Á ÁÁÁ Á ÁÁÁÁÁ f = 1 kHz, See Figure 2 ÁÁÁÁÁÁ Á ÁÁÁÁ Á ÁÁÁÁÁÁ C B = 1 mF, ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ ÁÁÁ Á Á Á ÁÁÁ dB ÁÁÁÁ ÁÁÁÁ Vn ÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Noise output voltage ÁÁÁÁÁ ÁÁÁÁÁ Gain = 1, R L = 32 W , ÁÁÁÁÁÁ ÁÁÁÁÁÁ C B = 0.1 mF, See Figure 20 ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ mV(rms)

4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Figure 1. Test Circuit

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

VDD – Supply Voltage – V OUTPUT POWER vs SUPPLY VOLTAGE 600 400 200 2.5 3.53 4 5.5 1000 P 4.5 5 O – Output Power – mW 800 THD+N 1% R L = 32 W R L = 8 W Figure 5 R L – Load Resistance – W 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% VDD = 5 V 500 600 VDD = 3.3 V 700 Figure 6

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

8 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

f – Frequency – Hz THD+N –Total Harmonic Distortion + Noise – % TOTAL HARMONIC DISTORTION PLUS NOISE vs FREQUENCY AV = –2 V/V VDD = 5 V PO = 350 mW R L = 8 W 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 = 175 mW VDD = 5 V R L = 8 W 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 W VDD = 5 V f = 1 kHz AV = –2 V/V 0.01 0.1 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 W AV = –2 V/V 0.01 0.1 1 0.01 0.1 f = 1 kHz f = 10 kHz f = 20 kHz

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

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 W PO = 0.25 W C I =1 mF 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 W PO = 0.35 W C I =1 mF 170 180 Gain Phase 101 102 103 104 105 106 Figure 18

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

APPLICATION INFORMATION

Figure 23 shows a linear audio power amplifier (APA) in a BTL configuration. The TPA301 BTL amplifier consists of two linear amplifiers driving both ends of the load. There are several potential benefits to this differential drive configuration but power to the load should be initially considered. 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

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

14 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

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. I DD rms /C0043 2V P /C0112R L P SUP /C0043V DD IDD rms /C0043 V DD 2V P /C0112R L Efficiency/C0043 P L P SUP Efficiency of a BTL Configuration/C0043 /C0112V P 2V DD /C0043 /C0112/C0466 P LR L 2 /C0467 1/C03242 2V DD (3) Where: (4) P L /C0043 V Lrms2 R L /C0043 V p 2R L V Lrms /C0043 V P 2/C0504 Table 1 employs equation 4 to calculate efficiencies for three different output power levels. The efficiency of the amplifier is quite low for lower power levels and rises sharply as power to the load is increased resulting in a nearly flat internal power dissipation over the normal operating range. The internal dissipation at full output power is less than in the half power range. Calculating the efficiency for a specific system is the key to proper power supply design. Table 1. Efficiency vs Output Power in 3.3-V 8-W BTL Systems † High-peak voltage values cause the THD to increase. indicates that as VDD goes down, efficiency goes up.

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 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 350 mW VO + VDD BYPASS IN – VDD /2 C S 1 mF C B 2.2 mF SHUTDOWN VO –8 GND From System Control 0.47 mF R I 10 kW R F 50 kW C F 5 pF Figure 26. TPA301 Application Circuit The following sections discuss the selection of the components used in Figure 26. The gain for each audio input of the TPA301 is set by resistors RF and RI according to equation 5 for BTL mode. amplifier be set between 5 kW and 20 kW . The effective impedance is calculated in equation 6.

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

16 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

component selection (continued) As an example, consider an input resistance of 10 kW and a feedback resistor of 50 kW . The BTL gain of the amplifier would be –10 V/V, and the effective impedance at the inverting terminal would be 8.3 kW , 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 kW 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, CF, of approximately 5 pF should be placed in parallel with RF when RF is greater than 50 kW . This, in effect, creates a low-pass filter network with the cutoff frequency defined in equation 7. (7) –3 dB fco fco(lowpass)/C00431 2/C0112R F C F For example, if RF is 100 kW and CF is 5 pF then fco is 318 kHz, which is well outside of 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 8. (8) –3 dB fco fco(highpass)/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 kW 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 Ifco

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 17POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 component selection (continued) In this example, CI is 0.40 mF so one would likely choose a value in the range of 0.47 mF to 1 mF. 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 TPA301 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 mF, 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 mF or greater placed near the audio power amplifier is recommended. 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-kW source inside the amplifier. To keep the start-up pop as low as possible, the relationship shown in equation 10 should be maintained, which insures the input capacitor is fully charged before the bypass capacitor is fully charged and the amplifier starts up. (10) /C0466C B /C0032250 kW /C0467 /C01181 /C0466R F /C0041R I/C0467C I As an example, consider a circuit where CB is 2.2 mF, CI is 0.47 mF, RF is 50 kW and RI is 10 kW . Inserting these values into the equation 10 we get: 18.2/C011835.5 which satisfies the rule. Bypass capacitor, CB, values of 2.2 mF to 1 mF 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 application. 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.

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

18 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

5-V versus 3.3-V operation The TPA301 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 TPA301 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-W 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 for a given output-power level than operation from 5-V supplies. 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 TPA301 data sheet, one can see that when the TPA301 is operating from a 5-V supply into a 8-W speaker 350 mW peaks are available. Converting watts to dB: P dB /C004310LogP W /C004310Log 3500 mW /C0043–4.6 dB Subtracting the headroom restriction to obtain the average listening level without distortion yields: –4.6 dB/C004215 dB /C0043/C004219.6 dB (15 dB headroom) –4.6 dB/C004212 dB /C0043/C004216.6 dB (12 dB headroom) –4.6 dB/C00429d B /C0043/C004213.6 dB (9 dB headroom) –4.6 dB/C00426d B /C0043/C004210.6 dB (6 dB headroom) –4.6 dB/C00423d B /C0043/C00427.6 dB (3 dB headroom) Converting dB back into watts: P W /C004310PdB /C032410 /C004311 mW (15 dB headroom) /C004322 mW (12 dB headroom) /C004344 mW (9 dB headroom) /C004388 mW (6 dB headroom) /C0043175 mW (3 dB headroom)

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 19POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 headroom and thermal considerations (continued) 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 350 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-W system, the internal dissipation in the TPA301 and maximum ambient temperatures is shown in Table 2. Table 2. TPA301 Power Rating, 5-V, 8-W , BTL

0 CFM

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000

20 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

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°–8° NOTES: A. All linear dimensions are in inches (millimeters). B. This drawing is subject to change without notice. C. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15). D. Falls within JEDEC MS-012

350-mW MONO AUDIO POWER AMPLIFIER SLOS208C – JANUARY1998 – REVISED MARCH 2000 21POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 MECHANICAL DATA 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°–6° 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.

Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using TI components. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright  2000, Texas Instruments Incorporated