Read Panasonic KX-DT333RU Service Manual online
11
KX-DT333RU/KX-DT333RU-B
4.2.7.
DXDP Communication
Function:
This circuit performs the same type of communication as between the DPT and PBX, but for a DXDP-compatible DPT con-
nected to the DXDP port.
In addition, power feed is also controlled.
nected to the DXDP port.
In addition, power feed is also controlled.
Circuit Operation:
The data to the slave DPT is output from pins 63 and 64 of IC2 and sent via the pulse transformer T2 to JK2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 61) built into IC2.
The threshold of the comparitor is determined by R19 to R21, which is input into to pins 60 and 62 of IC2.
The data from the slave DPT is sent through the pulse transformer and is input to the comparitor (pin 61) built into IC2.
The threshold of the comparitor is determined by R19 to R21, which is input into to pins 60 and 62 of IC2.
Power is supplied to the Slave DPT by means of a constant current circuit Q3 and Q4 as below:
• IC2 pin 58 H: Constant current circuit ON.
• IC2 pin 58 L: Constant current circuit OFF.
• IC2 pin 57 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 57 L: 20mA feed (initial supply to Slave DPT).
• IC2 pin 58 L: Constant current circuit OFF.
• IC2 pin 57 H: 40mA feed (normal supply to attached Slave DPT).
• IC2 pin 57 L: 20mA feed (initial supply to Slave DPT).
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