TDA7266SAN Datasheet, PDF (6/15 Pages) STMicroelectronics – 5 W + 5 W dual bridge amplifier

Application suggestions
4
Application suggestions
TDA7266SAN
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
C1 0.22µF
4
IN1
ST-BY R1 10K
7
C2
10µF
VCC
3
13
C5
470µF
+
1 OUT1+
-
C6
100nF
µP
S-GND
9
C3 0.22µF
IN2
Vref
12
MUTE ^{R2 10K}
6
C4
1µF
-
2 OUT1-
+
+
15 OUT2+
-
PW-GND
8
-
14 OUT2-
+
D95AU258A
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Doc ID 023621 Rev 1