BLE NRF52832 disconnect when driving electromechanical relay

[Stephane Lejeune]

Hello,

I build a custom board with Nrf52832  , to drive Relays , all works without load , no problem for drive the output.

When i put a load sometimes my device disconnect. i'm not sure but i think it is due the EMI pertubation.

Is any body have the same problem and found a solution.

Nota : if i add a snubber circuit on the contact the problem disappear . but the snubber circuit is not an universal solution.

Thanks in advance.

Stéphane

I put my schematics.

[ketil]

Hi Stéphane,

It is not possible for us to read the letters on the schematic. Could you please re-upload with higher resolution? Also, could you upload your PCB layout?

Ketil

[Stephane Lejeune]

Hello,

Maybe with this picture it is better.

regards

Stéphane

[ketil]

Hi,

We can't see any immediate errors with your schematic. In our designs we have used MOSFETs instead of bipolar transistors but both should work fine.

You can attach an oscilloscope to VDD and see if there is a drop when you switch the relay on that causes a brownout.

Sparkfun has a guide on using relays that might be useful.

Please see the attached schematic for an example of how we used a DPDT relay to drive a DC motor. 

Ketil