July 1994

8

Philips Semiconductors

Product specification

2 x 12 W hi-fi audio power amplifier

TDA1521

TDA1521Q

APPLICATION INFORMATION

Input mute circuit

The input mute circuit operates only during switching on and off of the supply voltage. The circuit compares the 1/2 supply

at pin 3 is determined by an internal voltage divider and the external 100

µF capacitor.

During switching on, a time delay is created between the reference voltage and the voltage at pin 3, during which the

input terminal is disconnected, (as illustrated in Fig.3).

Fig.3 Input mute circuit; time delay.