Samsung KCT52A, Training Manual

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KCT52A Chassis
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Power Supply Description PTR Drive Circuit Description
The control IC uses a proportional drive system to reduce the
PTR ON loss, saturation loss, and storage time loss.
When Proprot. drive circuit generates a positive pulse out of
Pin 5, the base current to Pin 3 (base of PTR) develops, and
increases linearly because of R813 and C851 combination.
This base current drives PTR to turn on.
When the driving pulse goes low, the R813 and C851 combi-
nation reverse biases PTR base completely to make sure the
the PTR is off.
The relation between Vbe (IB) and Vce (Ic) of the PTR is
shown on the graph.