Circuit with WROOM-02 microcontroller


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?

I’ve tried resolving this without help and found this resource: Development Board ESP-WROOM-02D - Share Project - PCBWay . But, not sure if it’s just to purchase the board or a guide to design the board.

Thanks for the assistance in advance.

The matter of interfacing logic devices operating from different voltage levels is an old and common one; “level translation” is a search term that should surface a variety of resources on the topic. Datasheets for devices in the Translators, Level Shifters product family may also be a useful source of information.

Are you sure the referenced output pin is of an open-collector type? Because if it’s not, attempting to simply pull a 3.3v output up to 5v isn’t likely to work and may cause damage.

Generally speaking, pull-up resistances are connected to the supply of whatever device a given I/O line is an input for; a device making 5V SPI signals generally needs a 5V source.

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Yes, it is.