Portable Class D Amplifier

The portable class D loudspeaker circuit is shown in Figure 1. This is a portable class D loudspeaker (commonly known as a loud speaker, hawker, electric horn) made with a phase-locked loop CD4046 and a TWH8751 high-power switch integrated circuit.

The audio signal is input from the 9th pin of IC2 phase-locked loop circuit, converted into variable frequency square wave by internal voltage-controlled oscillator VCO, compared and amplified by internal phase comparator 1 and output from 2nd pin, driven by VT1 to work IC3, and then driven by IC3 to make sound. When there is no signal input to the 9th pin of IC2 phase-locked loop circuit, the output level of 2nd pin is 0V, and IC3 stops working.

In the circuit of Figure 1, VT1 uses 9014, VD1 uses 1N4001, IC1 op amp uses CA3160, IC2 phase-locked loop circuit uses CD4046, and IC3 uses the high-power switch integrated circuit TWH8751 produced by Dahua Electronics Factory. High-power field-effect transistors and Darlington transistors can also be used as substitutes.