Panasonic KX-TDA0103XJ Service Manual page 37

KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X
2) 15VPT Output
During normal operation FET Q401 is ON and connected to 15V output. Then regulated 15V is output. At that time the
comparator IC401 output is high, and the transistor Q402 is OFF. When the 15VPT goes into the over current condition, the
voltage difference occurs at detection resistors R401, R402 and R403. The voltage of IC401 +terminal becomes lower than
that of -terminal, and then output of IC401 becomes LOW. Q402 turns ON and Q401 turns OFF. Consequently the fold back
current limiting shuts down 15VPT output.
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