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Electronic Volume Controller IC
PT2253A
FUNCTION DESCRIPTION
ATTENUATION SETTING
The Attenuation can be increased or decreased depending on the state of the U/D Pin (either “H” or “L”
Level) by actuating the built-in oscillator. When power is applied, the attenuation is automatically set at
-40dB.
POWER SUPPLY
U/D
OSC
-30dB
-32dB
-34dB
-36dB
-38dB
-40dB
When the DOWN Key is pressed, the U/D Pin goes to the “L” Level and the oscillator is actuated in the
down state. Thus, attenuation is increased.
Conversely, when the UP Key is pressed, the U/D Pin goes to the “H” Level and the oscillator is
actuated in the up state. Thus, attenuation is decreased.
Oscillation frequency (fosc) is dependent on the Cx and the Rx and is determined by the following
equation:
fosc
=
1
Hz
0.7 (Cx)(Rx)
where: Rs
≥
3Rx
PT2253A V2.8
-4-
December, 2005
PTC [ PRINCETON TECHNOLOGY CORP ]
