Circuit knowledge

A simple class AB power amplifier electronic project can be designed using the STA543SA a 3-channels audio amplifier IC with DC volume control dedicated for each single channel. STA543SA it is a device suitable for 2.1 audio system thank to its output configuration with two single ended channels and one bridge. This class AB power amplifier based on the STA543SA will provide a 24 watts output power on a single channel and 7 watts output power on the rest of channels . All output channels require a 4 ohms load .The Short Circuit Protection, the Thermal Protection and the Diagnostics Functions are integrated in the STA543SA power amplifier IC.
With this class AB power amplifier it is possible to amplify three analog signals Left, Right, Subwoofer coming from separated sources or to generate the BASS part to be sent to the Subwoofer via a passive crossover network .
The input Cut-off frequency is set by the external capacitor (C4,C8,C10) values and by the internal Input Impedance Rin ( 30KΩ typ) .
The stand-by can be easily activated by means of a CMOS level applied to pin 9 through a RC filter. In order to avoid the thermal protection intervention that is placed at Tj=150°C (Thermal Muting) or Tj=160°C (Thermal Shut-down), it is important the Heat Sinker RTH (°C/W)dimensioning.
A thermal heatsink with a value 4.3 °C/W will be required for three outputs (24W + 2 x 7 W) powered from a 14.4 volts DC .