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.

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