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Output overvoltage shutdown with NCP1239 and NCP1219?

Flyback

Well-Known Member
Hi,
AND9296 (PAGE 2) shows ncp1239 being used with an output overvoltage shutdown circuit involving D5, C6 and R7.
However, AND8393 (fig 25, PG 14) shows instead, an output overvoltage shutdown circuit involving just R11 and ZD1.
Why does Fig 25 not show the resistor and capacitor to ground from the SKIP/LATCH pin.?
Surely some capacitance on this pIn is needed to prevent false tripping?

Also, page 3 of the NCP1219 datasheet shows a "50us filter" in the SKIP/LATCH pin of the NCP1219. The SKIP/LATCH pin of NCP1219 is
virtually equivalent to the "FAULT" pin of the NCP1239. However, the block diagram for the NCP1239 does not show this "50us filter" in the equivalent pin ("FAULT" pin).
Why does NCP1239 lack this "50us filter"?, and does this mean the NCP1239 needs a bigger filter capacitor on the "FAULT" pin? (than the capacitor on the SKIP/LATCH pin of NCP1219)?

NCP1219

AND9296

AND8393
 

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