I am trying to interface an RFM69HW radio (3.3V device) with a Uno.
The Uno is powered by a 5V supply on its 5V (Vcc) input.
I am trying to power the RFM69 (GND & 3.3V pins) from the Arduino's 3.3V output.
When I put my DMM between GND and the RFM's 3.3V input, the voltage goes up to 3.95V and stays there for several seconds before eventually coming back down to 3.3V; and I suspect I have blown up a couple radios because of this.
I would prefer not to add an additional step-down converter (the final project is already pretty crowded), can't a 3.3V device be safely powered from the Uno's 3.3V output?
I am using the RFM69 at its lowest power setting, so max current should be ok.
The complete circuit is pretty simple, I am using 3 voltage dividers to feed the 3.3V RFM inputs:
Switching supply UNO RFM69HW +5V 5V GND GND GND 3.3V 3.3V MOSI divider MOSI MISO - MISO pin 2 - DIO0 SCK divider SCK NSS divider NSS