Typical circuit of LM4809/LM4810 for dual-channel headphone amplifier

As shown in the figure, this is a typical circuit of LM4809/4810 for dual-channel headphone amplifier. The left and right channel audio signals are input into the 2nd and 6th pins of LM4809/4810 (SOP/MSOP package) respectively, and are output from the 1st and 7th pins respectively after being amplified by the internal amplifier. They are added to the speakers of their respective channels through the coupling capacitor Co, and the amplifier gain Av = Rf/Ri. The 5th pin of LM4809 is connected to the shutdown control externally. When the 5th pin is connected to VDD (high level), it is allowed to work; when the 5th pin is grounded (low level), it is forbidden to work.