TDA7297SA Datasheet, PDF (3/11 Pages) STMicroelectronics – 10W+10W DUAL BRIDGE AMPLIFIER

TDA7297SA
ELECTRICAL CHARACTERISTCS (continued)
(V_CC = 13V, R_L = 8Ω, f = 1KHz, T_amb = 25°C unless otherwise specified)
Symbol
Parameter
Test Condition
R_i Input Resistance
VT_MUTE Mute Threshold
Vo = -30dB
VT_ST-BY St-by Threshold
I_ST-BY St-by Current V6 = GND
e_N Total Output Voltage
A Curve;
f = 20Hz to 20KHz
Min. Typ. Max. Unit
25
30
KΩ
2.3
2.9
4.1
V
0.8
1.3
1.8
V
100
µA
150
µV
220 500
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 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 7) 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 (C3, C5) 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
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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