Hi Team,
I would like to ask some help if you can contact the customer offline with his inquiry below:
Our customer is using LM139 as a cutoff switch.
The output of the comparator output seems to be oscillating at lower temperatures.
The circuit is supposed to turn off the MOSFET if the power supply droops due to a high load.
They are using a unregulated 15V to power the comparator as well as the positive comparator input: is not a regulated load;
When the 15 droops, it's supposed to shut off the MOSFET.
There is a volt between the comparator inputs, with the positive input very very close to the positive rail. The customer thinks that a volt should be plenty of margin.
Their simulations do not show any oscillation on the output.
Additional information:
The reference is a regulated output. So is the +28
All four outputs are oscillating. Also this IC is used for two identical circuits (Two amps are spares).
I can't share here the customer's schematic due to propriety reasons. I will give the customer's information offline.
Thank you very much.
Jonathan.
