Audio power amplifier circuit composed of LM4818

The picture shows the audio power amplifier circuit of LM4818. After the audio signal is input, it is coupled to the inverting input terminal (pin 4) of the amplifier through Ci and Ri coupling, while the non-inverting input terminal (pin 3) of the amplifier is AC grounded, and the amplified signal is output from pins 5 and 8. There is an indirect load between pins 5 and 8, such as a speaker, thus forming an inverting power amplifier circuit. There are two amplifiers inside LM4818. The external resistors RF and Ri determine the closed-loop gain of Amp A1; the two internal 20kΩ resistors can set the gain of the Amp A2 circuit to 1; the differential output gain Av=2RF/Ri.