The integrated circuit U4083B is a low-power audio amplifier for telephone loudspeakers. It has differential speaker outputs to maximize the output swing at low supply voltages. There is no need for coupler capacitors. The U4083B has an open-loop gain of 80 dB where the closed-loop gain is adjusted with two external resistors. A chip disable pin permits powering down and/or muting the input signal. Figure 1-1.