Comparator that latches for over current condition

[with2ls]

Much like treez in:

https://www.edaboard.com/threads/comparator-that-latches.270535/

I need a comparator that latches when an over current condition is sensed. Here is the basic operation flow:
1. CSA output fed to comparator.
2. When CSA output is greater than specified value, comparator changes state and latches.
3. Output of comparator is used to turn off a series FET, disabling power to the load (CSA output will now drop to 0).
4. Microcontroller periodically checks latch condition and attempts to reset the comparator (which re-enables power to the load).

I've implemented a similar design with the INA301 by TI (a CSA and latching comparator integrated into one package), but I now need something for higher voltage rails.

The following circuit adds the latching and resetting functionality to a common comparator, but at the expense of several extra parts (.asc file also attached).

Is there a simpler way accomplish the comparator+latch+reset functionality?
Or, are there integrated parts under a different name that I am missing?

 

[KlausST]

Hi,

I guess I'd rather use a 74xx1G74 flip flop at the comparator output..

Klaus

 

[BradtheRad]

Make a SR flip-flop from two cross-biased NPN. One or both sides can be darlington type if you need greater sensitivity. Transistors are available for high-voltage supply. But you can turn an NPN On by 5V at the bias terminal. A SR flip-flop needs only a momentary pulse to make it change state.

 

[crutschow]

I've implemented a similar design with the INA301 by TI (a CSA and latching comparator integrated into one package), but I now need something for higher voltage rails.

How high a voltage?
I've seen some that go to 60V such as this.

Best I came up with your circuit is to replace the reset MOSFET with a diode and resistor (below):
(My LTC1841 model is flaky, showing 200mV of input offset, so I used a different comparator).

 

[with2ls]

Thanks for everyone's input. I'll probably use Klaus' suggestion (normal comparator connected D flipflop with a clear).

 

[crutschow]

Thanks for everyone's input. I'll probably use Klaus' suggestion (normal comparator connected D flipflop with a clear).

You don't necessarily need a D flipflop, just a set-reset latch.

 

[KlausST]

Hi,

You don't necessarily need a D flipflop, just a set-reset latch.

True. But are there single gate RS flip flops? I once searched for them but could not find.

I only know about the D-FF types.

Klaus