STM32L4R5ZIT6P ESD Damage

[ym21]

Hello, 

I may have accidently either shorted or applied voltage to my UART TX and RX pins on my MCU which is on a custom PCB and now my PCB is pulling +60 mA of current under load. I am now experiencing difficulty programming the chip and I am getting errors such as "unable to recognize device" and "check power and cable". I wonder if exposing my UART pins to ground or power caused some sort of ESD or electrical damage inside the MCU and that combined with a longer power supply cable is causing a jump in current that makes it difficult to flash now?

Thank you.

[TDK]

Shorting GPIO pins to GND or VDD is not ESD damage and generally will not damage the chip.

> PCB is pulling +60 mA of current under load

So there likely is hardware damage. Could be that there are hardware issues that have caused damage cumulatively. Could be pins seeing overvoltage.

[STOne-32]

Dear @ym21 ,

Indeed it seems more like an EOS - Electrical Over Stress beyond the pins and product AMR - Absolute Maximum Rating . Can you keep your Reset/pin low and measure the current under reset and let us know ? If the current is excessive not few mA , the Device is damaged for sure .

Hope it helps you ,

STOne-32

[Mageee]

It looks like your MCU may have suffered Electrical Overstress (EOS) rather than simple ESD. Shorting UART pins alone usually doesn’t cause damage, but overvoltage or cumulative stress could explain the high current and programming errors. Measuring current with the MCU in reset can confirm if the device is damaged.

[ym21]

When I pull NRST down to ground, the PCB is pulling elevated levels of current.