Output Voltage; 15V Output; 15V Output Converter Switching Circuit; 15V Output Converter Controller Circuit - Panasonic KX-TDA0103XJ Service Manual

8.1.1.3.

Output voltage

This section explains mainly about the operation of circuit which converts the main converter output to 15V, 15VPT, 30V and
41V, and also explains about the over current protector of each output.

1) 15V Output

1-1) 15V Output Converter Switching Circuit

Main converter output voltage is stepped down by the switching operation of choke transformer T301 (Main winding), FET
Q302 and diode D310, then smoothed by electrolytic capacitor C305. The smoothed voltage is controlled by the voltage of
Pin 2 of IC301 (on Sub board) to get a constant voltage.
Refer to Fig. 3-1 (B).

1-2) 15V Output Converter Controller Circuit

The signal from controller circuit centering on IC301 (on Sub board) operates the switching part. The output from main
converter is stepped down and fed to the Vc terminal (Pin 7 of IC301). Then the oscillation signal from output terminal (Pin
6 of IC301) is led to the gate of FET Q302 to switch the voltage.
Refer to Fig. 3-1 (C).
1-3) 15V Output Over Current Protection Circuit
When Over Current flows to 15V output, the potential difference between terminals of R302 and R303 occurs. The voltage
potential difference turns ON Q301 to send the over current signal to the control circuit. Consequently 15V output shuts
down operating intermittently.
KX-TDA0103XJ / KX-TDA0104XJ / KX-TDA0108XJ / KX-TDA0103X / KX-TDA0104X / KX-TDA0108X
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