LM4901 audio power amplifier circuit (MSOP package)

As shown in the figure, this is the LM4901 audio power amplifier circuit (MSOP package). After the audio signal is input, it is coupled to the inverting input terminal (pin 5) of the amplifier through Ci and Ri, while the non-inverting input terminal (pin 4) of the amplifier is connected to ground through CB. After power amplification, it is added to the speaker from Vo1 (pin 6) and Vo2 (pin 10) in the form of bridge output. There are two amplifiers inside the LM4901. The gain of the first amplifier is determined by the ratio of the external resistors RF and R, and the gain of the second amplifier is fixed to 1 by two internal 20kΩ resistors. When the LM4901 outputs in the form of bridge differential, the gain of the power amplifier circuit Av=-RF／Ri. The maximum power consumption of the LM4901 bridge differential output form is PD(MAX)=4VCC2／2π2RL, which is usually 4 times that of the single-ended output form. The SD Mode pin (pin 3) is used to select the shutdown level. If this pin is grounded, the micro-power is shut down when the Shutdown pin (pin 1) is at a low level, and the amplifier works at full power when pin 1 is at a high level; if this pin is connected to VDD, the amplifier works at full power when pin 1 is at a low level, and the micro-power is shut down when pin 1 is at a high level.