I am designing a scaling op-amp circuit that requires approximately 500 mA of -10V power (-12V would be better so I don't have to rely exactly on a rail-to-rail op-amp). The circuit is scaling multiple -10V to 10V inputs by 0.10 (output = -1V to 1V).

However, the only power inputs I have available are +12V and +24V (5A and 10A, respectively). Is there a straightforward way to generate the required negative voltage rail? This is not as obvious as I had hoped, especially at the required power (I need to do this across 5 inputs, so all told worst-case is 500 mA).

  • 1
    \$\begingroup\$ If you only want to attenuate the signal, is a resistive divider enough? You might be able to do without the op amps entirely. Bear in mind that this would lead to a high output impedance, so if you don't have any sort of buffer after it (which would require a negative voltage supply anyway) it can't drive a low-impedance load. \$\endgroup\$
    – Hearth
    Commented May 3, 2017 at 4:13
  • 1
    \$\begingroup\$ Alternatively, if you can handle increased power supply noise, you could use the 12V power supply as a -12V supply, if it's isolated and capable of sinking current. Just connect its positive terminal to earth and its negative terminal becomes -12V. Then connect the negative terminal of the +24V supply to the negative of the 12V supply to get a +12V supply out of it. \$\endgroup\$
    – Hearth
    Commented May 3, 2017 at 4:17
  • \$\begingroup\$ An inverting switching converter would be a pretty straightforward solution. \$\endgroup\$
    – uint128_t
    Commented May 3, 2017 at 4:24

1 Answer 1


There are plenty of devices that can do what you want. Try searching for "inverting buck converter". Here's an image I found: -

enter image description here

You could even buy an isolating DC to DC converter and tie the positive output to 0 volts - this then gives you a negative 12 volt output. Also, flyback converters are useful for converting positive input to negative output.

The devil is in the detail (as with all switching regulators) so do a bit of research to check that any schematic offering can regulate from the range of input supply voltages you have specified.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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