TDA7266D
Figure 2. Microprocessor Driving Signals
+VS(V)
+18
VIN
(mV)
VST-BY
pin 9
1.8
1.3
0.8
VMUTE
pin 8
4.1
2.9
2.3
Iq
(mA)
VOUT
(V)
OFF
PLAY
MUTE
ST-BY
OFF
ST-BY
MUTE
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
5/13
STMICROELECTRONICS [ ST ]
