0
\$\begingroup\$

I am mainly interested to know the application of 0V output from a lab power supply. Which linear regulator IC one can use to get 0V output?

Edit:The LT3080 datasheet says that it is adjustable to 0V. How is it useful?

As far as I know, the well-known linear regulator LM317 can output as low as 1.25V but nothing less. However, this page 0 – 24 Volt, 2 Amp Bench Top Power Supply shows a linear power supply circuit that uses LM317 which can output 0V. Is it true?

\$\endgroup\$
3
  • 4
    \$\begingroup\$ Anything producing 0V is, in effect, a dead short circuit to the reference point of your measurement system. Are you trying, in fact, to generate a mid-rail voltage for something that would be labelled as 0V but is actually some voltage above or below a non-0V power rail? \$\endgroup\$ – Andy aka Sep 18 '14 at 12:36
  • 1
    \$\begingroup\$ This one can not output less than 1.25 V, but it is possible with second smaller negative supply that biases the feedback voltage divider. \$\endgroup\$ – venny Sep 18 '14 at 12:41
  • 4
    \$\begingroup\$ A piece of wire makes a pretty good 0 V supply. \$\endgroup\$ – Olin Lathrop Sep 18 '14 at 14:45
3
\$\begingroup\$

You can use a power supply as a general purpose analog source, not just for supplying a VDD pin.

For example, say you want to test the DC response of an ADC. You could connect the power supply output to the Vin terminal of the ADC and sweep it starting from 0 V.

I've also sometimes used a power supply as just a general purpose digital output (0 V or 3.3 V to an enable pin, perhaps).

\$\endgroup\$
3
\$\begingroup\$

You can get 0V from an LM317 trivially if you have a negative supply.

Just make a stable -1.25V supply and return the 5K pot part of the divider to that rather than to ground.

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

Yeah the posted circuit will not go down to 0 volts. It has a 1.25 Volt minimum as you observed. (Don't believe everything you read on the web :^) Also be careful using that circuit at low voltage and high current, the LM317 is may overheat and shut down.

\$\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.