K144 is stuck in the ESD test

[Louis1916]

The customer's engineer is doing the ESD test, and the external equipment is stuck, and the hardware reset on the board cannot be reset normally, and can only work normally if it is powered on again.The output interface is connected to the TVS tube,Whether the MCU is protected and cannot be reset by hardware?Thanks！

[judith75hodges · Accepted solution]

HELLO,

You can try with below Steps to Troubleshoot and Resolve:

Check the TVS Tube: Ensure the TVS tube is correctly rated for your circuit. Its breakdown voltage should be slightly above your operating voltage, and its clamping voltage must protect your components during an ESD event.
Inspect the Reset Circuit:

Take a close look at the MCU’s reset pin. Make sure the pull-up or pull-down resistors and any timing capacitors are properly set up. Also, confirm the reset signal lasts long enough to fully restart the CLIC AQUÍ MCU.
Use Decoupling Capacitors:

Add small, high-frequency capacitors (e.g., 0.1 µF) near the MCU’s power pins. This helps smooth out any voltage spikes caused by ESD.

Verify Proper Grounding: Ensure the PCB design has a solid ground plane. The TVS tube needs a good ground connection to divert ESD energy effectively.

Test for Latch-Up: After an ESD event, check the MCU’s current draw. If it’s unusually high, the MCU might be in a "latch-up" state, which often requires power cycling to fix. Adding resistors or improving bypass capacitors can help prevent this.

Check Power Stability: Make sure your power supply doesn’t dip or spike during an ESD event. A stable supply ensures the MCU and other components can recover properly without needing a full power cycle.