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TDA7266D

P1-P3P4-P6P7-P9P10-P12P13-P13
TDA7266D
4/13
APPLICATIVE SUGGESTIONS
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
µ
P) goes high and the voltage across the St-by terminal (Pin 9) 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 (C1, C3) 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
2
5
7
Vref
ST-BY
9
IN1
C1 0.22µF
V
CC
156
D02AU1409
+
-
-
+
OUT1+
OUT1-
19
16
14
MUTE
8
IN2
C3 0.22µF
+
-
-
+
OUT2+
OUT2-
20
13
S-GND
PW-GND
C5
470µF
C6
100nF
R1 10K
C2
10µF
µP
R2 10K
C4
1µF
1
10
11
5/13
TDA7266D
Figure 2. Microprocessor Driving Signals
B) Low Cost Application
In low cost applications where the mP is not present, 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.
So to avoid any popping or clicking sond, it is important to clock:
a Correct Sequence: At turn-ON, the Stand-by must be removed at first, then the Mute must be re-
leased after a delay of about 100-200ms. On the contrary at turn-OFF the Mute must be activated
as first and then the Stand-by.
With the values suggested in the Application circuit the right operation is guaranteed.
b Correct Threshold Voltages: In order to avoid that due to the spread in the internal thresholds (see
the above limits) a wrong external voltage causes uncertain commutations for the two functions we
suggest to use the following values:
Mute for Vcc>6.4V : VT = 2.3V
Mute for Vcc<6.4V : VT = Vcc/2 - 1
Stand-by : VT = 0.8V
+V
S
(V)
V
IN
(mV)
V
ST-BY
pin 9
I
q
(mA)
ST-BY
MUTE
PLAY MUTE ST-BY
+18
1.8
0.8
V
MUTE
pin 8
4.1
2.3
OFF
OFF
D02AU1411
V
OUT
(V)
2.9
1.3
TDA7266D
6/13
Figure 3. Stand-alone low-cost Application
PCB Layout and External Components:
Regarding the PCB layout care must be taken for three main subjects:
c) Signal and Power Gnd separation
d) Dissipating Copper Area
e) Filter Capacitors positioning
)Signal and Power Gnd separation:
c To the Signal GND must be referred the Audio Input Signals, the Mute and Stand-by Voltages and
the device PIN.13. This Gnd path must be as clean as possible in order to improve the device
THD+Noise and to avoid spurious oscillations across the speakers.
The Power GND is directly connected to the Output power Stage transistors (Emitters) and is crossed
by large amount of current, this path is also used in this device to dissipate the heating generated (no
needs of external heatsinker).
Referring to the typical application circuit, the separation between the two GND paths must be ob-
tained connecting them separately (star routing) to the bulk
Electrolithic capacitor C1 (470µF).
Regarding the Power Gnd dimensioning we have to consider the Dissipated Power the Thermal Pro-
tection Threshold and the Package thermal Characteristics.
2
5
7
Vref
ST-BY
9
IN1
C3 0.22µF
V
CC
156
D02AU1410
+
-
-
+
OUT1+
OUT1-
19
16
14
MUTE
8
IN2
C5 0.22µF
+
-
-
+
OUT2+
OUT2-
20
13
S-GND
PW-GND
C1
470µF
C2
100nF
C7
100nF
R1
47K
C4
10µF
R2
47K
1
10
11
P1-P3P4-P6P7-P9P10-P12P13-P13

TDA7266D

Mfr. #:
Buy TDA7266D
Manufacturer:
STMicroelectronics
Description:
Audio Amplifiers DUAL BRDGE AMPLIFIER
Lifecycle:
New from this manufacturer.
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