External input voltage supply for Nucleo-64 board

[Rainbow2601]

As per the user manual, we can power up a Nucleo-64 board by applying an external +5V to E5V and setting the jumpers accordingly. I have connected a TFT display with the uC board through SPI and the display is working fine. But what I am surprised about is, the moment I turn on the 5V from the DC power supply, the input voltage drops to around 3.2V. My question is, how can the 5V input change to 3.2V? Why is it getting dropped?

[S.Ma]

Check scgematics for silder bridge. Sometime there is a jumper to mesaure stm32 current. What happen of your 3.2V when removing the jumper. Another possible cause is overcurrent, protection diods conflicts with power rails, regluator not sized for extra current... etc....

[Sarra.S]

Hello @Rainbow2601​,

I think the reason the input voltage is dropping is the current draw from the other components on the board!

it is quite obvious that your supply cannot provide the necessary current required for the circuit to run

So you have to use a power source that can provide the sufficient current.

Hope that helps!