The TPA3112D1 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure that 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.

Optimum decoupling is achieved by using a network of capacitors of different types that target specific types of noise on the power supply leads. For higher frequency transients due to parasitic circuit elements such as bond wire and copper trace inductances as well as lead frame capacitance, a good-quality, low equivalent-series-resistance (ESR) ceramic capacitor from 220 pF to 1000 pF works well. This capacitor must be placed as close to the device PVCC pins and system ground (either PGND pins or PowerPAD) as possible. For mid-frequency noise due to filter resonances or PWM switching transients as well as digital hash on the line, another good-quality capacitor typically 0.1 µF to 1 µF placed as close as possible to the device PVCC leads works best. For filtering lower frequency noise signals, a larger aluminum electrolytic capacitor of 220 µF or greater placed near the audio power amplifier works well. The 220-µF capacitor also serves as a local storage capacitor for supplying current during large signal transients on the amplifier outputs. The PVCC pins provide the power to the output transistors, so a 220-µF or larger capacitor must be placed on each PVCC pin. A 10-µF capacitor on the AVCC pin is adequate. Also, a small decoupling resistor between AVCC and PVCC can be used to keep high frequency, Class-D noise from entering the linear input amplifiers.