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Why is voltage dropping too much in the 5V output Nucleo-STM32L432kc

Associate III

Hello, Im trying to power this board and sensor with 30mA power consumption @ 5V with 5V output of the board.

What im noticing is the board is not capable of mantaining the voltage with this light consumptions. It starts at 4.7-4.8v with nealy 0mA consumption and when the sensor starts working (around 30mA consumption) the voltage drops to 4.2v and the sensor fails. Why is the voltage dropping this much when the board should be capable of providing 300mA output?

Bob S

Have you looked at the NUCLEO schematic?

How are you powering the NUCLEO board? Via USB? External 5V? 7-12V? 3.3V?

And where are you taking the 5V off the Nucleo board to power your sensor?

Associate III

Hello Bob,

Yes, i've looked at the schematic but im very new to stm32 boards. I also have looked to the documentation where it says you can power devices from the 5V or 3v3 pins when the board is powered via USB or by Vin (500mA max, but 300mA max when powered from computer). Im powering the board from USB 5v. Computer or powered hub.

Im powering the sensor from this pin because it works at 5V and i have noise problems in the circuit, when powering the sensor from the board the noise is reduced i can initialize the device. If i try to power the sensor from other source like an external power supply bridging GNDs the device not initialize i think because of noise.