Hi all,

Does anyone know what this component is on the top of the photo? The component is found on a relay driving board for Arduino.

 

If I read it correctly it says M4 and I think it makes it a diode as below. Is it connected across a relay coil?

 

Hi all,

Does anyone know what this component is on the top of the photo? The component is found on a relay driving board for Arduino.


View attachment 205678

Thank you for your response! Yes, I think it's a rectifier diode too.
It is connected to the output of the MCP23017 i2c bus controller, I don't think it's connected to the coil of the relay.

 

It’s probably used as a fly back diode if it’s on a relay board. Possibly protecting that tiny mosfet below it. Confirm that is VCC on the via above it.

 

Typical circuit from a uP or IO expander to a relay.