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TONE Generation Circuit
4.2.4.
Function:
This circuit generates all system tones including COL, extension, busy, DTMF signals and key in confirmation tones during the
power failure mode and is comprised of IC1(DTMF Generator) and IC5 (Analog Switch).
Circuit Operation:
For an output of a single row tone, the row terminal and the each column terminals intersecting with it are required to be brought
a low state. For a dual tone output, one row terminal and one column terminal are brought to low state.
CONDITION
Ringing
Call Waiting
Tone Dial (Handset)
Tone Dial (Speakerphone)
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IC1 pin52
IC5 SWA
IC1 pin53
L
OFF
L
OFF
H
ON
H
ON
IC5 SWB
IC1 pin54
L
OFF
L
L
OFF
H
H
ON
L
L
OFF
H
9
IC5 SWC
IC1 pin55
IC5 SWD
OFF
H
ON
L
OFF
L
ON
L
KX-T7730CA
ON
OFF
OFF
OFF
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