How to generate a -24V signal

Question

I have to interface a specific motor, it has a weird driving board, I was in contact with the technical team from the manufacturer, and they told me that I have to send a -24V on a pin to allow it to turn. I have a +24V power supply, several step down modules, on 5V and 3.3V for my microcontrollers and other things.So here is my question: What is the simple way to produce a -24V voltage source from a 24V or lower one? I have searched a lot, but found nothing... My first idea was an inverting opamp, but if I were able to power it down to -24v then I would'nt need it at all :)

Any Ideas are welcome.

My ideas are now oriented to step down ICs able to output negative voltage from a positive one... I guess something around -18V should be enough to be understood by the driver.

Answer 1

Linear tech produce a number of inverting switchers like this: -

Check the data sheet to see if it can produce -24V. If not then use the search engine on this page here

There's also this one: -

Answer 2

Assuming the -24v is a control input, so doesn't need much current, and only needs approximately -24v, then a cheap, quick and dirty way is to use a charge pump. Like this.

^{simulate this circuit – Schematic created using CircuitLab}

What's drawn as an opamp is any circuit capable of making a rail to rail square wave.

The output is unregulated, and drops with increasing current.

If you do need exactly -24v, then you can use a 2 stage charge pump and regulator.

If you need more current than a few mA, then it's worth going to a magnetic solution, an inverting boost, rather than a charge pump.

Answer 3

An easy way is to use a DC-DC converter with an isolated output. For example, an PDS1-S24-S24-S. This particular one, while cheap, has a minimum output load requirement of 4mA so add an LED indicator or whatever if your load is insufficient (the consequence of insufficient loading is that the magnitude of the output voltage rises above the expected value).

Answer 4

What is the simple way to produce a -24V voltage source from a 24V or lower one?

You don't have to produce a new source. Because +24 and GND/0V is just a name for a potential we can switch the postitive and negative potential to get a negative voltage. Connect the "0V/GND" for your -24 Voltage to +24 and your -24V connector to 0V/GND.