I am trying to design an electronic fuse.

The circuit is powered at 24V and the fuse should disconnect the circuit when there is a current greater than 11A. Searching the internet, I found several configurations and decided on one.

I am using the following circuit to detect current with a shunt resistor (R5) on the high side:

enter image description here

I got some feedback and will be using an amplifier and comparator, IC1A as the amplifier and IC1B as the comparator.

What minimum characteristics would you recommend for these chips?

Is there anyone with experience in amplifier operations who knows what features are critical in this type of design?

I really only need to select the correct components at this stage of the circuit, because I will be using a P-MOS as a switch. It will be controlled via a transistor network which I can make myself, but I need a high or low signal coming from this stage of the circuit to know when I should turn off the P-MOS. Could someone help me with this?

  • \$\begingroup\$ Schematic incomplete? I see no switch. Specific part recommendations are off-topic..So consider rephrasing your question in terms of generic searchable opamp specifications like slew rate and GBW \$\endgroup\$
    – tobalt
    Jan 25 at 18:17
  • \$\begingroup\$ Welcome to Electrical Engineering! However, product recommendations are off-topic. Please see the help center for guidance on what questions are on-topic, and rephrase your question in a way that makes it on-topic. Also, I would advise you use an actual comparator instead of an op amp for the comparator application unless you really need to save money and/or size by using a dual op amp chip and are willing to make performance trade-offs. \$\endgroup\$
    – Null
    Jan 25 at 18:18
  • 1
    \$\begingroup\$ Good op amps do not make good comparators and vice versa. There are devices out there with an op amp, comparator, and reference in the same package, but specific product recommendations are off topic and considering you can get op amps in packages as small as 0.64 mm2, just getting two separate devices is probably easier for part sourcing etc. \$\endgroup\$
    – vir
    Jan 25 at 18:24
  • \$\begingroup\$ Ok I understand, I'll rephrase my question, thanks \$\endgroup\$
    – WalterPH
    Jan 25 at 18:31
  • 2
    \$\begingroup\$ Note that, when the comparator passes threshold, it turns the switch off, ceasing current. So the current drops below threshold, immediately turning it back on. You need a solution to prevent this from happening, to reproduce the behavior of a fuse. \$\endgroup\$ Jan 25 at 22:41


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