How can a regulator circuit deliver 1.8V at 320mA from a negative 12V/110mA power supply?
See “Neg-to-Pos Converter” for an example of a negative to positive converter using any flyback IC or controller. This same “buck-boost” approach can be used for your design. For your low power requirements, you will need only one flyback IC/controller, instead of the two shown in the higher-power example. The only complexity is how the feedback is created…this involves a PNP transistor, as shown in the example.
