Hi,
I need to generate -3.3V and -5.2V on my board. Power for -3.3V is 1.4W and -5.2V is 9.3W.

I have + 12V, -12V and +5V coming from the power board.

I am unfamiliar with generating these negative voltages. Does anyone have an idea on how to do this?
Inverting buck-boost converter?

Thanks!

 

Inverting buck-boost converter?

You could use inverting regulators from your positive supplies or linear regulators from your -12V supply (if it has sufficient capacity).

My go to for switching regulators is MC34063A. They're readily salvaged from a lot of devices.

 

The switching regulators would be a lot more efficient.
Linear regulators would dissipate 3.7W to generate -3.3V, and 12.2W to generate -5.2V from the -12V for your power requirements.
If you don't want to roll your own, you could likely buy some inexpensive modules from Amazon or Ebay.

 

What current are you requiring?

 

What current are you requiring?

I need to generate -3.3V and -5.2V on my board. Power for -3.3V is 1.4W and -5.2V is 9.3W.

So, .424A for -3.3 and 1.788A for -5.2