Reset Circuit; Power Supply Circuit - Panasonic KX-T7665AL Service Manual

KX-T7665AL / KX-T7665X

10.4. RESET CIRCUIT

Reset Signal is outputted from IC7 and inputted into IC2, IC3 and IC6 at the connection of TEL cord.

10.5. POWER SUPPLY CIRCUIT

This circuit converts the voltage supplied from PBX into the power supply voltage of +3.3V by IC1 (Switching Regulator IC).
Q22 and Q23 control the power supply circuit as below to turn IC1 on in low consumption current at starting up.
· Input Voltage approx. 26V or less →Q23 OFF →Q22 ON →IC1-pin 3 H →IC1 OFF
· Input Voltage approx. 26V or more →Q23 ON →Q22 OFF →IC1 ON
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