15
KX-TGC210LAB/KX-TGC212LAB/KX-TGC213LAB/KX-TGC220LAB/KX-TGC222LAB/KX-TGC223LAB/KX-TGCA20LAB
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
R111
C111
Q111
BBIC pin 5 [BELL]
When the CPU (BBIC) 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
D101
Q141
Q161
R163
D101
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 6 of BBIC 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 BBIC.
4.4.6.
Parallel Connection Detect Circuit/Auto Disconnect Circuit
Function:
In order to disable call waiting and stutter tone functions when using telephones connected in parallel, it is necessary to have a
circuit that judges whether a telephone connected in parallel is in use or not. This circuit determines whether the telephone
connected in parallel is on hook or off hook by detecting changes in the T/R voltage.
Circuit Operation:
Parallel connection detection when on hook:
When on hook, the voltage is monitored at pin 17 of IC501. There is no parallel connection if the voltage is
0.54 V or higher, while a parallel connection is deemed to exist if the voltage is lower.
Parallel connection detection when off hook:
When off hook, the voltage is monitored at pin 18 of IC501; the presence/absence of a parallel connection is determined by
C120
1000p
R1
3
1
10M
L1R
R1
33
33
0k
VDDC
C111
0.047u
R141
100k
C142
K
0.01u
C124
NC
L1T
C1
3
2
K
0.01u
+
3
.0V
R112
100k
R11
3
10k
C186
10p
R142
2.7k
C12
3
NC
R145
2.2k
R111
100k
C11
3
K0.68u
R121
3
90k
R122
3
90k
C112
0.047u
Q142
B
C
E
*SA101
3
00V
SA10
3
NC
2
1
Q111
D11
3
AK
D1
33
AK
D15
3
NC
AK
R164
2.7k
R161
100k
C168
NC
R151
100k
C152
0.01u
R177
1k
Q171
Q161
B
C
E
C161
10u
R165
2
7k
+
3
.0V
C164
NC
RA151
1k
1
2
3
4
C181
NC
C184
1u
C16
3
NC
D101
1
4
3
2
C101 680p
C102 680p
C121
680p
C122
680p
R16
33
9
R152
1
3
0k
R176
1k
R175
3
.9k
R172
680k
C176
1
u
R114
47k
1
2
*D142
25V
C17
3
0.1u
C167 1000p
C171
0.022u
C175
560p
C178
0.0
33
u
R160
820
R171
220
R168 4.7k
*R115
NC
*C115
NC
*P101
*Q141
*D14
3
NC
*SA102
NC
*R162
47k
Hook
Hook
BELL
BELL
Pin 5 of IC501
Pin 6 of IC501
Pin 18 of IC501
Pin 17 of IC501
Pin 16 of IC501
Pin 25 of IC501
Pin 24 of IC501
Pin 28 of IC501
Содержание KX-TGC212LAB
Страница 58: ...58 KX TGC210LAB KX TGC212LAB KX TGC213LAB KX TGC220LAB KX TGC222LAB KX TGC223LAB KX TGCA20LAB Memo ...
Страница 65: ...65 KX TGC210LAB KX TGC212LAB KX TGC213LAB KX TGC220LAB KX TGC222LAB KX TGC223LAB KX TGCA20LAB Memo ...
Страница 68: ...68 KX TGC210LAB KX TGC212LAB KX TGC213LAB KX TGC220LAB KX TGC222LAB KX TGC223LAB KX TGCA20LAB Memo ...
Страница 72: ...72 KX TGC210LAB KX TGC212LAB KX TGC213LAB KX TGC220LAB KX TGC222LAB KX TGC223LAB KX TGCA20LAB Memo ...