Samsung KCT52A, Training Manual

Page: 9 / 93

KCT52A Chassis
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SAMSUNG GROUP
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SAMSUNG GROUP
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TOC
9
Power Supply Description Start up Circuit
When AC cord is plugged in, the initial current starts flowing
through the path as shown, and charges C852.
When Vin reaches about 8V, the control circuit is activated,
and the oscillation begins.
D1, D2 windings provide the necessary back-up current to Vin
after the control circuit is activated as the initial current alone
can not sustain the current consumed by the control IC.
The DI winding voltage is set between the threshold of Stop
voltage (Vin=5.1 V) and Overvoltage (Vin=10V).
As shown in the graph, D1 and D2 winding voltages are
necessary to power up the control IC.