0
\$\begingroup\$

The 741 op amp has a rugged design with a short circuit protection feature if any one could shed the light on this mechanism where I have found it to be on of the most power efficient protection circuits that would not drain the power of a battery. I would really appreciate it and thank you in advance for you efforts!

\$\endgroup\$
4
\$\begingroup\$

If you look at the circuit diagram of a 741

enter image description here

you will see this at the top of the output stage...

enter image description here

The output path is through Q14 and R6. When the current though R6 is high enough it turns on Q15 which starts to turn off Q14. This limits the amount of current it can ever source to about ~0.6V/27R = ~20mA.

It is your basic current limiter circuit.

A similar circuit, PNP version, exits below that to limit the sink current.

\$\endgroup\$
  • 1
    \$\begingroup\$ I do something similar for resolver excitation circuits to ensure they are short-circuit protected \$\endgroup\$ – JonRB Oct 27 '17 at 17:16

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.