CF8223A 查看數據表（PDF） - Nippon Precision Circuits

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CF8223A

FSK Decoder and DTMF Receiver IC

Nippon Precision Circuits  

SM8223A

VRIG

VDD

0.7VDD

VSS

0.3VDD

Point a Signal

VRIG

VDD

0.7VDD

VSS

0.3VDD

Point b Signal

VDD

0.7VDD

VSS

0.3VDD

Point c Signal

VDD

0.7VDD

VSS

0.3VDD

Point d Signal

Figure 2. Ring signal detector circuit waveform transitions

The voltage divider level and RC time constant are

given by the following equations, respectively.

0.7V DD

=

--------------R---1---------------

R1 + R2 + R3

⋅

V

RIG

C1R4=

------------------t-------------------

I



n



V-----D--V--D---D--–--D---V----T--

where t is the guard time, and the trigger level satis-

fies the expression 0.3VDD ≤ VT ≤ 0.7VDD.

NIPPON PRECISION CIRCUITS—10

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