I have designed short circuit protection circuit that you can find in the image.



When you supply 24V from L1 pin and there is no GND(no short circuit) in L2 pin, circuit conducts L1-24V to L2 pin. If there is a short circuit in L2 pin, circuit switch off the gate.

When i test the circuit by shorting L2 to GND , sometimes it can not separate L2 from L1 because bc817s are still a little conducting, overcurrent flows from drain to source over protection diode of mosfet and p channel mosfet(FDS9958) is being damaged.

What can i do to improve stability of this circuit?

Many thanks,

  • \$\begingroup\$ The circuit seems overly complex for what it actually does. What exactly is the function of Q10, R10 and R13? \$\endgroup\$ – Dave Tweed Apr 2 at 13:28
  • \$\begingroup\$ I've designed NAND Gate with Q10 and Q9. Mean, if L1 has 24V and L2 has 24V over L1 and R9 , open the gates:) (conduct L1 to L2) \$\endgroup\$ – Gkhan Apr 2 at 13:38
  • \$\begingroup\$ What max current can the 24V source provide? \$\endgroup\$ – Huisman Apr 2 at 20:15
  • \$\begingroup\$ Max current is 1A \$\endgroup\$ – Gkhan Apr 3 at 8:13

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