NXP DesignsのトピックLPC540: Voltage at ADC input before VDD

LPC540: Voltage at ADC input before VDD

jana_beck — Wed, 06 May 2020 18:14:20 GMT

Hi,
I have a design, where I am trying to measure voltages with a LPC54016.
One ADC input is a voltage, that will be on an ADC pin, before the MCU gets powered.

I have VCC_5V that gets converted into VCC_3V3 with a step down DCDC converter.
I have 5V going to an ADC input (with a voltage divider, so it is 2.25V at the pin).
That means, that the 2.25V will be on the ADC pin before 3.3V at the power supply pins.

Can this damage the MCU?

Thanks,
Jana

Re: LPC540: Voltage at ADC input before VDD

Omar_Anguiano — Fri, 08 May 2020 18:59:25 GMT

Hello Jana Beck

Due to the internal circuitry, it is not recommendable to apply voltage to the pins before powering the VDD, this may cause you trouble with the MCU.

I apologize for the inconvenience this is causing you, if you have more questions do not hesitate to ask me.

Best regards,

Omar