Hello,
the Arduino Nano Every uses a MPM3610 to generate 5 V from a 7…21 V supply voltage (to VIN in the circuit below).
It is also possible to power the Arduino from USB. In that case the USB 5 V goes via D2 to the “+5V” that is connected to the MPM3610 OUT pin (with VIN of the Arduino board left unconnected). Due to the D2 voltage drop the “+5V” is in fact only 4.65 V.
Looking at the MPM3610 Functional Block Diagram I would expect this 4.65 V at the MPM3610 OUT to flow back to the MPM3610 IN via the energy store inductor, high-side MOSFET body diode and RSEN, resulting in something like 4 V to show up at the Arduino VIN pin.
Strange enough I do measure 5.46 V at VIN (unloaded). When connecting a 330 Ohm resistor from VIN to ground the voltage drops slightly to 5.38 V (I= 16mA).
Where is this voltage coming from? Is the MPM3610 in some way working in “reverse gear”?
Thanks,
Rik
Hi Rik,
Welcome to the MPS Technical Forum. I can only answer questions specifically on MPS devices. For more information on Arduino products, please visit their website.
If you are planning to connect a 5V source to the output node of the MPM3610, even with Vin disconnected, I strongly advice against this. I am confused what you mean by “unloaded” when you saw the 5.46V on the input. Did you measure the input pin while driving the output with a separate 5V source? Have you done any testing with the MPM3610’s input and output completely isolated from the rest of the board?
Sure it is likely switching. Vin is powered initially through the body diodes and that gets the chip ENabled then it starts switching as Vout is too low and that causes it to run as a synchronous boost converter from the point of view of Vout to Vin.
Try grounding the enable pin and see what it does. If that clears it up then you have to add a transistor driven from Vusb to ground the en in the event that
You care about this and the Vusb is present.