1
2
4
Vref
ST-BY 7
IN1
C1 0.22µF
VCC
133
D95AU258A
+
-
-
+
OUT1+
OUT1-
15
14
12
MUTE 6
IN2
C3 0.22µF
+
-
-
+
OUT2+
OUT2-
8
9
S-GND
PW-GND
C5
470µFC6
100nF
R1 10K
C2
10µF
µP
R2 10K
C4
1µF
Figure 1: Microprocessor Application
ELECTRICA L CHARACTERI STICS (Continued)
Symbol Parameter Test Condition Min. Typ. Max. Unit
VTST-BY St-by Threshold 0.8 1.3 1.8 V
IST-BY ST-BY current V6 = GND 100 µA
eNTotal Output Noise Voltage A curve
f = 20Hz to 20kHz 150 µV
APPLICAT ION SUGGES TION
STAND-BY A ND MUTE FUNCTION S
(A) Microprocessor Application
In order to avoid annoying "Pop-Noise" during
Turn-On/Off transients, it is necessary to guaran-
tee the right St-by and mute signals sequence.
It is quite simple to obtain this function using a mi-
croprocessor (Fig. 1 and 2).
At first St-by signal (from mP) goes high and the
voltage across the S t-by terminal (Pin 7) starts t o
increase exponentially. The external RC network
is intended to t ur n-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 (C3,
C5) st ar t to charge.
It’s necessary t o 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.
TDA7266
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