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PT2256 V1.7

- 7 -

August, 2006

Electronic Volume Controller IC

PT2256

INITIALIZATION WHEN POWER ON

PT2256 has an auto-initialization function during the Power On period. When Power is turned ON, the

volume level is set to the initial value of -46 dB by setting the RST pin to “L” level. Please refer to the

diagram below.

VD D

/R ST

0V

VIL

VD D

T

T1 m s

≥

BACK UP WHEN POWER OFF

When the /INH Pin is set at “L” Level, all input and output pins are disabled and the current

consumption is reduced to the minimum. Under this condition, the backup becomes possible. Please

refer to the diagram below:

VD D

VD D

0V

4.5V

No rm al M ode

B ac kup M ode

No rm al M ode

Bac ku p

VD D m in > 4 .5 V

B ac ku p D ata is los t

The backup circuit is given below:

IN4 001

10 K

1 000 F /16 V

µ

+

-

10 K

51 K

P T 2256

VD D

VSS

/I NH

VDD

VSS

Note:

If the VDD drops from 12V to 4.5V, then the backup is possible for a period of 6 days. However, if

VDD-Vss drops below 4.5V, the backup becomes impossible.