TDA7266L Datasheet, PDF (3/7 Pages) STMicroelectronics – 5W MONO BRIDGE AMPLIFIER

TDA7266L
ELECTRICAL CHARACTERISTICS (Continued)
Symbol
VTST-BY
I_ST-BY
eN
Parameter
St-by Threshold
ST-BY current V6 = GND
Total Output Noise Voltage
Test Condition
A curve
f = 20Hz to 20kHz
Min. Typ. Max. Unit
0.8
1.3
1.8
V
100
µA
150
µV
APPLICATION SUGGESTION
STAND-BY AND MUTE FUNCTIONS
(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 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, 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) start to charge.
Figure 1: Microprocessor Driving Signals.
+V_S(V)
+18
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.
(B) Low Cost Application
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 the supply line
and the external capacitor C4 is intended to delay
the St-by and mute threshold exceeding, avoiding
"Popping" problems.
V_IN
(mV)
V_ST-BY
pin 7
1.8
1.3
0.8
V_MUTE
pin 6
4.1
2.9
2.3
I_q
(mA)
V_OUT
(V)
OFF
ST-BY
MUTE
PLAY
MUTE
ST-BY
OFF
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