STM32L071 Operation Failure and Power Line Resistance

[JinMoon]

Hello.
I recently experienced an unusual MCU Problem and need to analyze it. Please help me.

The FW program download to the MCU is successful, but it does not operate after a reset.

I performed a short circuit test after disconnecting the power(Battery)

but even when measuring VCC-GND and GND-VCC at the power supply, a resistance value of approximately 500 ohms is detected.

When I disconnect only the MCU from the PCB and re-measure, the 500 ohm value disappears from the PCB

but this value persists when measuring directly from the MCU pins.

Can I conclude that the MCU is dead due to a power supply failure?

And in what cases does this problem occur?

[mƎALLEm]

Hello @JinMoon and welcome to the ST community,

---

@JinMoon wrote:

but even when measuring VCC-GND and GND-VCC at the power supply,

---

Do you mean VDD-GND? the power supply pins of the MCU?

[TDK]

500 ohms is lower than it should be and indicates damage. Damage typically results from an overvoltage condition.

But if it still connected and programmed, the application is likely running with an increase current draw.