Application suggestions

TDA7266SAN

6/15

Doc ID 023621 Rev 1

4

Application suggestions

Standby and mute functions

4.1

Microprocessor application

In order to avoid annoying "pop noise" during turn-on/off transients, the correct sequence of

the st-by and mute signals must be ensured which is quite simple when using a

microprocessor (Figure 3 and 4).

First the st-by signal (from the microprocessor) goes high and the voltage across the st-by

terminal (pin 7) starts to increase exponentially. The external RC network is intended to turn

on slowly the biasing circuits of the amplifier, in order to avoid "pop" and "click" on the

outputs.

When this voltage reaches the st-by threshold level, the amplifier is switched on, and the

external capacitors in series to the input terminals (C3, C53) start to charge.

The mute signal must be held low until the capacitors are fully charged, in order to avoid that

the device goes in play mode causing a loud "pop noise" on the speakers.

A delay of 100 - 200 ms between the st-by and mute signals is suitable for proper operation.

Figure 3.

Microprocessor application

1

2

4

Vref

ST-BY

7

IN1

C1 0.22

µF

VCC

13

3

D95AU258A

+

-

-

+

OUT1+

OUT1-

15

14

12

MUTE

6

IN2

C3 0.22

µF

+

-

-

+

OUT2+

OUT2-

8

9

S-GND

PW-GND

C5

470

µF

C6

100nF

R1 10K

C2

10

µF

µP

R2 10K

C4

1

µF