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Part of my circuit needs -12v. What would be the simplest way to get this, considering I have a +12v supply already available in the circuit? I need ~500ma

I searched for -12v regulators on Mouser, but many of these needed a negative voltage input.

Ideally looking for an IC that can handle this.

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  • \$\begingroup\$ Related: Obtaining a -3.3v with +3.3v and ground \$\endgroup\$
    – The Photon
    Aug 2, 2018 at 22:18
  • \$\begingroup\$ Added the current. :) \$\endgroup\$
    – 19172281
    Aug 2, 2018 at 22:18
  • \$\begingroup\$ Try searching for voltage inverter or voltage converter \$\endgroup\$
    – MartinF
    Aug 2, 2018 at 22:25
  • \$\begingroup\$ There are 555 timer based inverters but not rated for 500 mA. What you need is a form of 'boost converter'. Use that as a search term. \$\endgroup\$
    – user105652
    Aug 2, 2018 at 22:32
  • \$\begingroup\$ You did not mention all avail. Input power sources \$\endgroup\$ Aug 2, 2018 at 23:03

2 Answers 2

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There are a number of ways to get a negative, below ground supply.

  • Easiest: If the source is AC, uses a full-wave bridge connected opposite to that of the positive supply.
  • If DC only is available, use an inverter that may use
    • a charge pump for low currents or
    • an inductor or transformer for higher currents.

The Texas Instruments TPS54620 is a step-down (buck) converter, which can be configured to provide a voltage below ground, e.g. this circuit from Digikey.

An Analog Devices LT8331 could supply 80 mA at - 12 VDC.

LT8331 -12 VDC supply from http://www.analog.com/en/technical-articles/differences-between-the-uk-converter-and-the-inverting-charge-pump-converter.html

An inverting charge-pump such as the Microchip TC1044S can 20 mA, if that meet your needs.

It is even possible to use the 555 timer/oscillator to get -12 VDC, though regulation would not be good.

555 Negative Charge Pump from http://colourtvservicebbsr.blogspot.com/2016/04/12vdc-negative-voltage-dc-converter-by.html

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You can leverage the fact that the Buck-Boost Topology is inherently inverting - these are a few examples of Reference Designs that do just that:


PMP7330 - Positive 12V to -12V (0.1A) buck-boost converter (Schematic) (Test Results) Positive 12V to -12V (0.1A) buck-boost converter


PMP7207 - Generic TPS40200 Inverting Buck Boost Reference Design (Schematic) (Test Results) Generic TPS40200 Inverting Buck Boost Reference Design


PMP2224 - Buck-boost (-12V @ 0.5A) for the TPS5430 (Schematic) (Test Results)

Buck-boost (-12V @ 0.5A) for the TPS5430


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