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I have a custom amplifier board that works with some scientific equipment. There is a molex-type connector on the PCB that requires +5V, -5V, and ground (3 pins). When I try to search for a +/- split power supply, I can find lots of do-it-yourself instructions for how to create the split supply, but no ready-made commercial product that I can just plug in. (Not expecting my specific connector, but screw terminals or banana jacks or something...

Are there commercial products to supply split +/-5V and I'm just using the wrong search terms? If not, is there some reason, given how common this need is for analog components?

thegreatemu
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    Yes, dual laboratory power supplies and others exist. You however tell very little about what properties you need, like current or ripple. – Justme Jul 14 '21 at 22:43
  • Old school method used by HP was make +/-7V supply then used dual LDO’s on each load. Or send 5/-5V ref and a buffer on each regulated with unity gain. – Tony Stewart EE75 Jul 14 '21 at 22:56
  • @Justme I'm using a benchtop lab power supply now, but it seems like overkill. I eventually need at least 5 of these, and getting a benchtop supply for each one can't be the optimal solution – thegreatemu Jul 14 '21 at 22:58
  • What power level / output current? – AnalogKid Jul 15 '21 at 00:02
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    Digikey shows 71 models of +/- 5v dual rail power supply in stock. A solution I prefer when designing my own (lower power) boards is to put a charge pump voltage inverter to convert +5 into -5v and then run everything off of 5v. You can also use a 5.25v supply and LDOs if you require low noise. – user1850479 Jul 15 '21 at 00:35
  • Yes, just search for a dual output AC/DC converter or DC/DC converter with +5V and -5V outputs. – vir Jul 14 '21 at 22:09
  • This is a low power application. The board is totally custom and didn't come with a current spec, but it's only powering a few source-followers – thegreatemu Jul 15 '21 at 17:06
  • @user1850479 these are not boards we're designing; they already exist and we just need to run them. I have no idea why the designers decided to take split supply input rather than splitting it on the board, but that's what we're working with – thegreatemu Jul 15 '21 at 17:09
  • @TonyStewartEE75 I could certainly have our in-house electronics guys whip something up, but it will cost 100X more than buying a commercial supply. I just could not find the right keywords to search with – thegreatemu Jul 15 '21 at 17:11

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There are many many ±5V supplies. Look on Digikey or Mouser under DC DC converters, choose your search terms to be two output, look for packages that are SIP. If you're looking for a bench top supply and dual benchtop supply will probably work for your application.

This is a good way I've used in the past to obtain -5V, the same converter (in a different configuration ) can generate +5V.

Generating negative voltage rail using P7805 DC-DC converter

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Voltage Spike
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  • was hoping for AC input, but the DC-DC converters seem like the best solution. I'm using a dual-output benchtop now but it's overkill (and I need 5 of them) – thegreatemu Jul 14 '21 at 22:51
  • The most common way with AC to DC 'wall warts' is to use a single supply, then use a DC DC converter to make two rails. – Voltage Spike Jul 14 '21 at 22:52
  • Simplest way from mains is to get a split secondary transformer (like a 10-0-10 output) and regulate the output (trivially with 7805 and 7905). Depend on how much current you need. Or just take a +5 supply and apply an inverting converter. – Lorenzo Marcantonio Jul 15 '21 at 07:30
  • @LorenzoMarcantonio This is a good inverting -5V converter, the same converter can be used for +5V and they are in 7805 compatible packages. https://electronics.stackexchange.com/questions/454778/generating-negative-voltage-rail-using-p7805-dc-dc-converter/454786#454786 – Voltage Spike Jul 15 '21 at 15:43