TPA6304-Q1 Class-D Audio Amplifier Texas Instruments TPA6304-Q1 Class-D Audio Amplifier is a four-channel analog-input Class-D Burr-Brown™ audio amplifier that implements a 2.1MHz PWM switching frequency. This device enables a cost-optimized solution in a very small 2.7cm2 PCB size, high impedance single-ended inputs, and full operation down to 4.5V for start/stop events.