TDA7266D
Figure 2. Microprocessor Driving Signals
+V
S
(V)
+18
V
IN
(mV)
V
ST-BY
pin 9
1.8
1.3
0.8
V
MUTE
pin 8
4.1
2.9
2.3
I
q
(mA)
V
OUT
(V)
OFF
ST-BY
PLAY
MUTE
MUTE
ST-BY
OFF
D02AU1411
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
Mute for Vcc<6.4V
Stand-by
: VT = 2.3V
: VT = Vcc/2 - 1
: VT = 0.8V
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STMICROELECTRONICS [ STMICROELECTRONICS ]
