Obsolete Product(s) - Obsolete Product(s) Obsolete Product(s) - Obsolete Product(s)
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
APPLICATION 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 to
increase exponentially. The external RC network
is intended to tur n-on slowly the biasing circuits of
the amplifier, t his 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.
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.
(B) Low Co s t Applica tion
In low cost applications where the µP is not pre-
sent, the suggested circuit is shown in fig.3.
The St-by and mute terminals are tied together
and they are connected to the supply line via an
external voltage divider.
The device is switched-on/off from t he supply line
and the external capacitor C4 is intended to delay
the St-by and mute threshold exceeding, avoiding
"Popping" problems.
+VS(V)
VIN
(mV)
VST-BY
pin 7
Iq
(mA)
ST-BY MUTE
PLAY MUTE ST-BY
+18
1.8
0.8
VMUTE
pin 6
4.1
2.3
OFF
OFF
D96AU259
VOUT
(V)
2.9
1.3
Figure 1: Microprocess or Driving Signals.
TDA7266L
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