STM32G070CBT6 IC pins shorted internally

[patrick-reddesigns]

Hi,

I have made up six boards and three of them had an unusually high standby current (35mA instead of 1mA).

Eventually, when the IC was removed, we found Pins 5 & 6 of the removed IC were shorted internally (0.3R)
They were also shorted to pin 45 with 3.7R. The other two boards are showing similar shorts.

The board worked fine with a new MCU.

Does anyone know what might cause this short?

TIA,

Patrick.

 

[TDK]

> STM32G070CB76 

Not a chip. Probably STM32G070CBT6?

Pins shorted indicates hardware damage. Probably due to overvoltage at one point. Does L3 cause VREF+ to spike at powerup? What is attached to LED_WHITE?

[patrick-reddesigns]

Thanks, typo in chip code corrected to STM32G070CBT6.

LED_WHITE connects through a resistor to a led.

VREF+.. I don't know - some kind of intermittent event? These are the second batch of boards - the first 10 had no issues with hundreds/thousands of power-ups.

Could ESD be an issue?

[CTapp.1]

Yep, it could be ESD.