8.2.2.1 Select the PWM Frequency

Set the PWM frequency by using AM0, AM1 and AM2 pins.

8.2.2.2 Select the Amplifier Gain and Master or Slave Mode

In order to select the amplifier gain setting, the designer must determine the maximum power target and the speaker impedance. Once these parameters have been determined, calculate the required output-voltage swing which delivers the maximum output power.

Choose the lowest analog gain setting that produces an output-voltage swing greater than the required output swing for maximum power. The analog gain and master or slave mode can be set by selecting the voltage divider resistors (R1 and R2) on the GAIN/SLV pin.

8.2.2.3 Select Input Capacitance

Select the bulk capacitors at the PVCC inputs for proper voltage margin and adequate capacitance to support the power requirements. In practice, with a well-designed power supply, two 100-μF, 50-V capacitors should be sufficient. One capacitor should be placed near the PVCC inputs at each side of the device. PVCC capacitors should be a low-ESR type because they are being used in a high-speed switching application.

8.2.2.4 Select Decoupling Capacitors

Good-quality decoupling capacitors must be added at each of the PVCC inputs to provide good reliability, good audio performance, and to meet regulatory requirements. X5R or better ratings should be used in this application. Consider temperature, ripple current, and voltage overshoots when selecting decoupling capacitors. Also, these decoupling capacitors should be located near the PVCC and GND connections to the device in order to minimize series inductances.

8.2.2.5 Select Bootstrap Capacitors

Each of the outputs requires bootstrap capacitors to provide gate drive for the high-side output FETs. For this design, use 0.22-μF, 25-V capacitors of X5R quality or better.