NCP1239 Fault pin current

[cupoftea]

Hi,
The NCP1239 has a fault pin, for use in overtemperature shutdown.
A 44uA current flows out of it. You shoudl connect an NTC to it.
This then produces a voltage, and if under 0.43V, then you trip on overtemp.

But most NTCs are 10k at 25c...and 10k*44uA = 0.44V.

This seems a bit too near to the trip point, may i ask have i missed something.?

NCP1239

https://www.onsemi.com/pdf/datasheet/ncp1239-d.pdf

 

[KlausST]

Hi,

on page 20 there is a whole section about NTC calculation. It´s clear that one can not focus on 10k NTCs.

Klaus