I am trying to design a circuit using a WROOM-02 microcontroller, which requires a 3.3V@500mA power supply. The input power for the circuit is 12V, and the SPI bus that needs to be connected to the WROOM-02 operates at 5V. I am looking for options to provide a 5V power supply for the pull-up MISO line, as the WROOM-02 is a slave. One option is to use a dual output LDO, but these are difficult to find with the necessary specifications. Another option is to use a daisy chain of regulators, but this would require a larger 500mA 5V regulator to regulate the 3.3V supply. I am also considering using a 5V zener for the pull-up, but I am unsure about the power consumption and what value would be best for this application. Are there any other alternatives or recommendations for this situation?
This is completely off topic for this board but if you need that much current at 3.3V then you need to use a switching supply, an LDO dropping that much power will generate a lot of heat for a small board.
If you want to layout your own switcher circuit there are more elegant ways to do this but for low volumes it’s often easier to just use an all in one module.
So depending on the exact power requirements at 5V either an off the shelf 12V to 5V switcher module and then an LDO from 5 to 3.3V or a 12V to 3.3V switcher and a low minimum draw LDO or some other means for generating a low current 5V source from the 12V.