As shown in the figure, the LM4906 audio power amplifier is a typical application circuit (MSOP package). After the audio signal is input, it is applied to the inverting input terminal (4 pins) of the amplifier through C2 coupling. After power amplification, it is added to the speaker as a bridge output from Vo1 (5 pins) and Vo2 (8 pins). The LM4906 has two internal amplifiers. The gain of the first amplifier can be controlled by the gain selection terminal (3 pins). When the 3 pin is low, the gain is 6dB. When the 3 pin is high, the gain is 12dB. The second amplifier gain is fixed to 1 by two internal 20kΩ resistors. When the LM4906 is output in the form of bridge differential, the gain Av of the power amplifier is 2 × 20kΩ / 20kΩ or 2 × 40kΩ / 20kΩ. When the 1 pin is logic low, the amplifier's micropower is turned off. When it is logic high, the amplifier operates at full power. Sealed Special Transformer,Oil Immersed Distribution Power Transformer,Low Noise Distribution Transformer,Oil Immersed Distribution Transformer Shaoxing AnFu Energy Equipment Co.Ltd , https://www.sxanfu.com