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

(mV)

pin 9

(mA)

ST-BY

MUTE

PLAY

MUTE

ST-BY

+18

1.8

0.8

pin 8

4.1

2.3

OFF

OFF

D02AU1411

(V)

2.9

1.3