I am trying to incorporate a LEM LAH 100-P current sensor into a project. It requires a dual polarity voltage supply between +/- 12 and 15 volts. What is the best way to implement it?

Digi-key has an article which references many other application notes. But I don't have knowledge of power electronics which makes adapting them difficult. This application note seems promising but components used are for an output of -3.3 to -5.5 volts (part at digikey and datasheet).

Figure from the application note: enter image description here

What components could be used to create a negative supply of 12 to 15 volts? Any suggestions welcomed.

  • 2
    \$\begingroup\$ Charge pump is probably a good match for your requirement (~10 mA). Did you look at Maxim's other charge pump parts? \$\endgroup\$
    – The Photon
    Jan 31, 2018 at 1:17
  • 3
    \$\begingroup\$ Just buy a +/- 12V module such as this: digikey.com/products/en/power-supplies-board-mount/… \$\endgroup\$ Jan 31, 2018 at 1:21
  • \$\begingroup\$ What input will you provide AC ? DC? Output is only 10mA @+/-15V \$\endgroup\$ Jan 31, 2018 at 1:38
  • \$\begingroup\$ Take a look at ICL7662. Old charge pump chip that works well and still around. \$\endgroup\$ Jan 31, 2018 at 1:48
  • 2
    \$\begingroup\$ @VincePatron the ICL7662 switches at an annoyingly audible 10 kHz. Better to use a higher frequency part. \$\endgroup\$
    – τεκ
    Jan 31, 2018 at 4:48

2 Answers 2


As it already has been stated in different comments to the original question, there are different possibilities.

You could use in increasing order of complexity:

  • a DC/DC power supply module (typically a plug and play 'block')
  • a charge pump (essentially a controller IC with capacitors)
  • an inverting switching power supply (essentially a controller IC with inductor)
  • an added winding on an existing AC/DC power supply

Since you ask this question, I would suggest you select the first option. Not the cheapest but it is the most fail safe.

For the first 3 options, you can easily use the selection criteria at the large component distributors (Mouser, Farnell, Digi-Key, RS) and select the appropriate input and output voltage range and output current requirement.


An easy solution is to use a 780X DC to DC power converter, you could even mock one up for use on the bench with wire and an iron.

Below is shown for a 5V supply, they also have 12V or 15V that would be the same circuit but different part.

Do not get this confused with a 7805 linear regulator, a 7085 linear regulator will not generate a negative voltage and requires a negative rail. Because DC to DC converters can sink current, they can generate negative voltages.

enter image description here

Just to clear up confusion, this is a DC to DC converter:

enter image description here
Source: https://www.cui.com/product/resource/p7805-s.pdf


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