I have a PCB connected to SAMD21 Xplained. I power SAMD21 board using external power supply on 5.0V_IN pin. I use this same pin to power the connected PCB. However, this connected PCB doesnt work (This boards contains something like an oscillator IC which just outputs 1V DC in this case).
When I tried applying external voltage to VCC pin instead of 5.0V_IN, the IC on my connected PCB worked, I was getting a sine wave from the oscillator. However, Vcc is supposed to be output voltage, not input.
Is there any suggestion as to why this would happen?