Dxdp Communication - Panasonic KX-T7633 Service Manual

10.7. DXDP COMMUNICATION

Function
This circuit performs the same communication as DXDP-compatible DPT and PBX
communication connected with DXDP port.
Circuit Operation
The data to Slave DPT is outputted from pin 63 and 64 of IC5 and sent by Transistor Q8 and Q9.
The data from Slave DPT is inputted to the comparator(pin 61) built in IC5.
The threshold voltage of the comparator is determined by R65 to 67 and inputted to pin 60 and 62.
Also, the supplying power to Slave DPT is controlled by a constant current circuit of Q15 as
below.
- IC5-pin 58 as H : Constant current circuit ON
- IC5-pin 58 as L : Constant current circuit OFF
- IC5-pin 57 as H : 40mA Feeding (Slave DPT usually)
- IC5-pin 57 as L : 10mA Feeding (Slave DPT at starting up only)
20