5

Application suggestion

Standby and mute functions

(A) Microprocessor application

Turn-on/off transients, guarantee the right ST-BY and mute signal sequence.

This function can be got thanks to a microprocessor (Figure 3. Microprocessor application and

Figure 4. Microprocessor driving signals).

At first ST-BY signal (from microprocessor) goes high and the voltage across the ST-BY terminal (Pin 7) starts to

increase exponentially. The external RC network turns on slowly the biasing circuits of the amplifier, 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, C5) start to charge.

The mute signal must be kept low until the capacitors are fully charged, so to avoid that the device goes to play

mode causing a loud "Pop Noise" on the speakers.

A delay of 100 - 200 ms between ST-BY and mute signals is suitable for a proper operation.

Figure 3. Microprocessor application

1

2

4

Vref

ST-BY

7

IN1

C1 0.22µF

VCC

13

3

+

-

-

+

OUT1+

OUT1-

15

14

12

MUTE

6

IN2

C3 0.22µF

+

-

-

+

OUT2+

OUT2-

8

9

S-GND

PW-GND

C5

470µF

C6

100nF

R1 10K

C2

10µF

µP

R2 10K

C4

1µF

TDA7266

Application suggestion

DS0184 - Rev 11

page 6/17