I am trying to use two switch-mode regulators to create a split supply, where the first one regulates the positive voltage as per the application schematic in the datasheet and the second one works the same way, but references its output to GND and uses the GND pin as the negative voltage output. Is this valid? Here is my schematic:


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    \$\begingroup\$ Forgetting the top half of that schematic... what do you think the bottom half is going to do wired that way? \$\endgroup\$ – Trevor_G Aug 25 '17 at 17:00
  • \$\begingroup\$ I think that by using the system GND at its voltage output it will cause the regulator's GND reference to be pushed to -5V. \$\endgroup\$ – Billy Kalfus Aug 25 '17 at 17:02
  • \$\begingroup\$ Vin of the lower regulator is connected to "GND". Where does it get its "-36V" from? \$\endgroup\$ – Janka Aug 25 '17 at 17:10
  • \$\begingroup\$ I see what you're saying - I believe I connected the inputs wrong. What about something like this: imgur.com/1AmKCFk \$\endgroup\$ – Billy Kalfus Aug 25 '17 at 17:13
  • \$\begingroup\$ WHat you propose simply wont work.. Read photons answer..... \$\endgroup\$ – Trevor_G Aug 25 '17 at 17:27

You can make an LM2576 produce a negative regulated voltage - read the data sheet: -

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You need to follow the circuit above to make it work this. A lot of buck regulators can be "pushed" into this mode of operation BTW such as this one from LT: -

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Or this one: -

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Some SEPIC controllers can also be used this way: -

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| improve this answer | |
  • \$\begingroup\$ Thank you! Must have missed this - guess I need to RTFM. \$\endgroup\$ – Billy Kalfus Aug 25 '17 at 17:41
  • \$\begingroup\$ What does the "F" stand for LOL? \$\endgroup\$ – Andy aka Aug 25 '17 at 17:42
  • \$\begingroup\$ Usually something like "read the freaking manual" \$\endgroup\$ – Billy Kalfus Aug 25 '17 at 17:42
  • \$\begingroup\$ Although you can force them, really it's better to use the right part for the job. \$\endgroup\$ – Trevor_G Aug 25 '17 at 18:21

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