TDA7576B

Principle of operation

Doc ID 023511 Rev 3

11/17

4

Principle of operation

The TDA7576B is an innovative stereo audio amplifier meant for 24 V battery vehicles. The

amplifier works in a single-ended configuration without the large decoupling capacitors on

the outputs normally required by the s.e. topology. Its principle of operation is depicted in

Figure 11.

Figure 11.

Amplifier structure

Channel 1 is electrically inverting its input signal whereas channel 2 is not; if the speakers

are connected with the positive pole of speaker 2 connected to Out2 and the negative pole

of speaker 1 connected to Out1, then the two channels both behave as non-inverting.

Speaker 1 and speaker 2 have one terminal in common and further connected to a half Vcc

(HVCC) buffer.

If the signals at In1 and In2 are identical, then the voltage at Out1 and Out2 is identical in

magnitude but inverted (Out1 = -Out2), and the current flowing through speaker 1 is all

coming from speaker 2, with no current going into the HVCC buffer. If the signal at In1 is not

identical to that at In2, then the signal at the two outputs will not be identical either, and

some current will flow into or out of the HVCC buffer, keeping the voltage at HVCC constant.

This structure allows therefore the amplifier to operate in a single-ended configuration with

no need for decoupling capacitors.

Mathematically this can be expressed as: