ESP32 failing IEC61000-4-6 (Conducted Immunity).

[cadrjr1]

Hi,
we have just had our ESP32-based PCB fail IEC61000-4-6 (Conducted Immunity).
The PCB is a simple control panel with 4 Capacitive Buttons (using the ESP32s Touch Capability).
When the buttons are operated while the test is in the 280KHz band, the PCB invariably locks up (buttons don't respond).
(I wouldn't have expected problems at this low frequency.)
As the frequency sweep increases,the board often recovers.

I have checked out all the obvious - off-board power supply, on-board DC-DC, grounding, etc. to no avail.
The PCB, needless to say, is designed with all the Espressif design recommendations in mind.

I now believe the problem may be related to the ESP32 WROOM2 module itself or the code running on it.

Has anybody else experienced failures of this particular type while developing commercial ESP32 designs ?

R

[ESP_Sprite]

Do just the buttons lock up, or does the entire ESP32 crap out? I'm wondering if the 280KHz signal somehow synchronizes with the button sampling or something...

[cadrjr1]

Hi,
only the PCB Touch functions seem to screw up.
The PCB drives a DAC, a relay and some LEDs. These all seem to behave OK.

Any ideas, anything I could tweak would be welcome ...
Thanks
R

[ESP_Sprite]

You could perhaps try to tweak the measurement time using `touch_pad_set_meas_time` to get around this, but I don't quite know enough about this to be sure. You can try emailing sales@espressif.com, they have more experience handling EMC problems.

[cadrjr1]

Thank you I will do that.
R