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FUNCTION DESCRIPTION

(1) Setting Of Attenuation

After power on, attenuation is automatically set at -40dB.

Figure 2

V.1.0

When the UP key is pressed after power ON, the U/D terminal is placed in the up state at

' H ' level, and the oscillator is actuated.

When the DOWN key is pressed, t

DOWN key is pressed, and the oscillator is actuated in the down state and therefore,

attenuation is decreased. Oscillation frequency is decided by Cx and Rx.

fosc≒

(Hz) (Rs≧3Rx)

1

0.7 Cx * Rx

POWER SUPPLY

U/D

Figure 1

osc

VDD

OSC

RS

CX

RX

UP

DWOM

VSS

U/D

RX=33 K

Ω

CX=4.7

µF

RS=100 K

Ω

+

OSC

-30dB

-32dB

-34dB

-36dB

-38dB

-40dB

SM7153

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