Panasonic Generation Plasma Display Television Technical Manual page 54

Vsus/Vda Circuit
The 3.2V from pin 11 of connector P25 is applied to the PANEL_MAIN_ON pin (24) of the POWER
CPU (IC501). When pin 24 goes high, pin 14 goes low to provide the ground path to turn on the LED
within the photo-coupler IC507. The light from the LED turns on the phototransistor within the photo-
coupler and its collector (pin 4) goes low to turn off Q540. When Q540 is off, the DC voltage from the
rectifier D586 is applied to the gate of Q507 turning it on. Q507 outputs the VSUS voltage. The VSUS
voltage is also used to turn on Q527 to output the VDA.
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