Dear Sir
Please, answer
We use LM239AN comparators in the circuit, please, see attach. Power supplies +12V-1 and +12V-2 have common negative output and it connected to GND. LM239 is used for “evaluate” voltage at the R2, to know the approximate current. Microcontroller determines the time of LM239’s check. Supression diode VD1 and DA1 are used for protect input of LM239 at case of short circuit, when current through the resistor R2 may be 100-150A during 10 ms, until overcurrent protection work (overcurrent protection circuit, not shown in Figure) Comparators breaks down sometimes (other elements do not fail). How do you think, why? May be, to use another comparator? May be to add an additional protection between GND and +12V-1? We have more than 200 pcs LM239 in these devices.
TIA
Sincerely
Vladimir Naumenkov
www.agat.by
