Panasonic KX-DT543-B - DXDP Communication

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KX-DT543/KX-DT543-B/KX-DT546/KX-DT546-B
4.2.4. DXDP Communication
Function:
This circuit performs the same type of communication as between the DPT and PBX, but a slave DPT for DXDP is connected to
the DXDP port.
In addition, it controls power feeding for a slave DPT.
Circuit Operation:
The data to the slave DPT is output from pins 47 and 48 of IC300 and sent via “Q331C331” and “Q332C337” to JK301.
The data from the slave DPT is sent through “C337R350” and is input to the comparator (pin 22) built in IC300.
The threshold voltage of the comparator is determined by R353, R354 and R355. It is input into pin 21 and 23 of IC300.
Power is controlled to the Slave DPT by means of a constant current circuit Q303 and Q304 as below:
• IC300 pin 20 H: Constant current circuit ON.
• IC300 pin 20 L: Constant current circuit OFF.
• IC300 pin 25 H: 40mA feed (normal supply to Slave DPT).
• IC300 pin 25 L: 20mA feed (initial supply to Slave DPT).
JK301
1
2
3
4
5
Q303
Q304
1
E1
2
B1
3
C2
4
E2
5
B2
6
C1
H-D
L-D
R319
R320
C312
C313
C325
R322
DG
R321
PG
PG
PG
C332
C331
R342R343
VDD33
DG
DG
DG
C330
R340
R341
R312
R313
Q332
1
E1
2
B1
3
C2
4
E2
5
B2
6
C1
DG
C337
R348
R349
DG
VDD33
DG
C333
DG
C334VDD3 VDD33
C335
DG
C336
R350
R351R352
R353R354
R355
DGDGDG
D532
D533
L303
L304
Q331
1
B1
2
E
3
B2
5
C1
4
C2
Q330
R345
R346R347
TO DPT/SLT
IC300
ASIC1
47
48
DDX0
DDX1
DVRH
23
22
DDR
21
DVRL
20
GPIO3
25
GPIO4