TDA7266D
APPLICATIVE SUGGESTIONS
STAND-BY AND MUTE FUNCTIONS
(A) Microprocessor Application
In order to avoid annoying "Pop-Noise" during Turn-On/Off transients, it is necessary to guarantee the right St-
by and mute signals sequence.It is quite simple to obtain this function using a microprocessor (Fig. 1 and 2).
At first St-by signal (from µP) goes high and the voltage across the St-by terminal (Pin 9) starts to increase ex-
ponentially. The external RC network is intended to turn-on slowly the biasing circuits of the amplifier, this 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 (C1, C3) start to charge.
It's necessary to mantain the mute signal low until the capacitors are fully charged, this to avoid that the device
goes in play mode causing a loud "Pop Noise" on the speakers.
A delay of 100-200ms between St-by and mute signals is suitable for a proper operation.
Figure 1. Microprocessor Application
V
CC
C5
470µF
C6
100nF
C1 0.22µF
6
15
7
9
IN1
+
-
2
OUT1+
R1 10K
ST-BY
C2
10µF
S-GND
µP
13
-
5
OUT1-
OUT2+
Vref
+
C3 0.22µF
14
IN2
+
-
19
R2 10K
MUTE
8
C4
1µF
1
10
11
20
-
16
OUT2-
PW-GND
+
D02AU1409
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STMICROELECTRONICS [ ST ]
