15
KX-TG6440PK/KX-TGA641S/KX-TGA641T/KX-TGA740B
4.4.5.
Telephone Line Interface
Telephone Line Interface Circuit:
Function
• Bell signal detection
• ON/OFF hook and pulse dial circuit
• Side tone circuit
Bell signal detection and OFF HOOK circuit:
In the idle mode, Q141 is open to cut the DC loop current and decrease the ring load. When ring voltage appears at the Tip (T)
and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows:
T
→
L101
→
R111
→
C111
→
Q111
→
DSP pin 58 [BELL]
When the CPU (DSP) detects a ring signal, Q141 turns on, thus providing an off-hook condition (active DC current flow through
the circuit). Following signal flow is the DC current flow.
T
→
L101
→
D101
→
Q141
→
Q161
→
R163
→
R167
→
D101
→
L102
→
P101
→
R
ON HOOK Circuit:
Q141 is open, Q141 is connected as to cut the DC loop current and to cut the voice signal. The unit is consequently in an on-
hook condition.
Pulse Dial Circuit:
Pin 59 of DSP turns Q141 ON/OFF to make the pulse dialing.
Side Tone Circuit:
Basically this circuit prevents the TX signal from feeding back to RX signal. As for this unit, TX signal feed back from Q161 is
canceled by the canceller circuit of DSP.
Summary of Contents for KX-TG6440PK
Page 2: ...2 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B ...
Page 28: ...28 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 4 10 Signal Route ...
Page 29: ...29 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B RF part signal route ...
Page 31: ...31 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 5 2 Display ...
Page 35: ...35 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B ...
Page 36: ...36 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 7 1 2 Programming using the Direct Commands ...
Page 37: ...37 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B ...
Page 38: ...38 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 7 2 Error Messages ...
Page 39: ...39 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 7 3 Troubleshooting ...
Page 40: ...40 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B ...
Page 41: ...41 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B ...
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Page 67: ...67 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 11 1 2 Handset ...
Page 68: ...68 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 11 1 3 Charger Unit ...
Page 69: ...69 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B 11 2 How to Replace the Handset LCD ...
Page 89: ...89 KX TG6440PK KX TGA641S KX TGA641T KX TGA740B Memo ...