Power Supply Circuit - Panasonic KX-TC1872B Service Manual

KX-TC1868B / KX-TC1871B / KX-TC1872B

13.4. Power Supply Circuit

Function:
Power from the AC adaptor passes through a regulating block consisting of IC301.
Circuit Operation:
IC401 is a regulated power supply. The voltage at point A is regulated to 4.5 V by IC301.
The voltage at point B is dropped by D306 and D307 to 4.1 V.
The voltage at point C is dropped by D511 to 3.8 V.
The voltage at point D is dropped by Q304 to 4.3V
The voltage at point E is dropped by Q312, Q601 to 4.1V
13.5. DTMF Signal
When the DTMF data from the Handset is received, the DTMF signal is output from pin 36 of IC501 and sent to the line through
Q131.
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