0
\$\begingroup\$

I just designed a two stage miller compensated operational amplifier, I am not sure how to measure it's maximum output current, Can you give me a precise definition of this current?

\$\endgroup\$
  • 1
    \$\begingroup\$ Strictly speaking, the maximum current would be the short-circuit current. Connect the output directly to ground and measure the current that flows through the connection as the op amp attempts to drive the output voltage to the power supply rails. \$\endgroup\$ – Elliot Alderson Jan 3 at 17:12
1
\$\begingroup\$

The precise definition of that current is whatever the manufacturer means. Usually a manufacturer will limit the output current so that a designer won't destroy parts by asking too much -- but in the case of power op-amps, or other specialty op-amps, that may not be the case.

The two most likely definitions of "maximum output current" are "this is the most you'll get with the output shorted to one rail or another", or it is "don't ever exceed this or you'll let out the magic smoke".

\$\endgroup\$
1
\$\begingroup\$

One way you could measure it would be to put the op amp in a voltage follower mode. Then put a current source on the output and slowly turn it up from 0mA. Don't go over the short circuit current rating defined in the datasheet.

If you need more current than the output you can use a booster circuit like this one:

enter image description here

Source: www.ti.com/lit/an/snoa600b/snoa600b.pdf

If your only using a single sided supply, then you only need one half of the output stage.

enter image description here

https://www.allaboutcircuits.com/technical-articles/how-to-buffer-an-op-amp-output-for-higher-current-part-1/

\$\endgroup\$

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.