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KX-TG3661JXM/KX-TG3662JXM/KX-TG3668JXM/KX-TG3669JXM/KX-TGA365JXM
4.4.4.
Reset Circuit
Function:
This circuit is used to initialize the microcomputer when it incorporates an AC adaptor.
Circuit Operation:
The system is reset when IC9’s BBIC internal voltage of BB1.8V goes down below 1.65V.
4.4.5.
Telephone Line Interface
Telephone Line Interface Circuit:
Function
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
• Pulse dial circuit
• Side tone circuit
Ring signal detection:
In the standby mode, Q3 is open to cut the DC loop current and decrease the ring load. When ring voltage appears at the Tel_T and
Tel_R leads (When the telephone rings), the AC ring voltage is transferred as follows:
Tel_T
→
LF1
→
IC1 Pin 1
Tel_R
→
LF1
→
C9
→
R5, R6, R7
→
IC1 Pin 8
Ring signal from T-R is input to Ringer IC1 and output from pin 5 of IC1. Then it is detected through the following route.
IC1 5pin
→
R13
→
PC1
→
IC9 Pin 63 (BELL)
Clip (:Calling Line Identification presentation: Caller ID) signal detection:
The Clip signal voltage is transferred as follows;
Tel_T
→
C20
→
R20
→
C137
→
IC9 Pin 107 (CIDin+)
Tel_R
→
C21
→
R23
→
C138
→
IC9 Pin 112 (CIDin-)
ON/OFF HOOK Circuit:
Q2 is turned ON when IC9 detects the Ring signal, the handset of base unit is off-hook or the TALK key of the handset is
pressed. This causes Q3 to be turned ON and the line will be closed. (The Line Loop state).
Tel_T
→
LF1
→
D3
→
Q3
→
Q9
→
R27
→
R28
→
Q10
→
D3
→
LF1
→
Tel_R [OFF HOOK]
Pulse Dial Circuit:
Pin 94 of DSP IC9 (HOOK/DP) turns Q2 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 Q9 is
canceled by the canceller circuit of DSP (IC9).
TX
RX
Parallel
Connection
OFFHOOK DET
SHANT
DP
HOOK
