Electrical – Power Arduino Pro Micro from MCP2025 Vreg


I'd like to power Arduino Pro Micro (5v) from MCP2025-500 LIN BUS transceiver.

Can I connect MCP2025-500 Vreg pin directly to Arduino Pro Micro (5v) RAW pin?

Best Answer

No you can't connect to the RAW pin input if you want to run your MCU at 5 V.

You need to connect to the UVVC input and may have to solder closed a jumper position on the PCB depending on whether you bought the board as a 3.3 V or 5V version.
If your board has a MIC5219-3 then the RAW input is typically 5 V.
If your board has a MIC5219-5 then the RAW input is typically greater than 5 V.

The dropout voltage for the MIC5219-5 (you said you were using a 5 V unit) means the input voltage should be more than 5.175 - 5.25 V or you are under the dropout limit.

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You can easily power your Pro Micro from the MCP2025 (max 70 mA output) since the ATMega32u4 will only draw an absolute maximum of about 27 mA (16 MHz @ 5 V). To this you must of course add any I/O current you draw from the output pins to GND. This could easily add to more than the MCU draws, so be careful here.

In the ATMega 32u4 datasheet read Table 29-1 and carefully read and understand the notes to the table. The total I/O sink current (which is sourced from your power supply) cannot exceed 100 mA total.