The schematic is made by Great scott (a YouTuber).I need to know can we add a current limit to it by using a sense resistor and feeding the sensed voltage proportional to the current in the feedback controller opamp?enter image description hereMy question is can I add the output of this current limit part to the voltage feedback controller opamp?(in the inverting input)?enter image description hereenter image description here

  • \$\begingroup\$ You've summed up what you need to do; put a shunt resistor in line on of the power rail, use an op-amp to amplify the voltage across said resistor. The question is what you do with this current limit, do you want a micro controller to read it? Do you want the signal to trigger a transistor to turn something off/on? \$\endgroup\$ – Puffafish Aug 29 '18 at 15:37
  • \$\begingroup\$ Yeah my bad ..I forgot to mention that .I was going for adjustable current limiting. \$\endgroup\$ – Hrituraj Singha Roy Aug 29 '18 at 15:56
  • \$\begingroup\$ And what happens when there is an over current event? \$\endgroup\$ – Puffafish Aug 29 '18 at 16:00
  • \$\begingroup\$ Well that is why i wanna add a current limit function to it @Puffafish \$\endgroup\$ – Hrituraj Singha Roy Aug 29 '18 at 16:33

With this topology, it's not possible to implement a current limit. See the current path? It's from the Vcc power source through L1 and D1 into the load.

There is no switched element in that path.

To add a current limit, you'd had to add a switch in the current path. Because a conducting MOSFET has lower losses than a diode, it is adviseable to put another MOSFET in instead of the diode D1.


simulate this circuit – Schematic created using CircuitLab

The path over R_limit and the diode is for preventing T1 and/or T2 to be shot by overvoltage if T1 is opened while current is flowing through L1 and T2 is not opened because of the current limiting function.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.