Intersting problem of ESD

[vaibhav.k]

Hi friends

I am facing one critical problem related to ESD.We have designed Patient monitor.which have USB,Ethenet and VGA connectivity.Machine is SMPS and Battery operated.When we connect machine on Mains we connect earth terminal at that time machine operate normally.But when we operate machine battery we disconnect earth terminal and at that time if i touch any metallic part to internal mounting plates and any connector of USB Ethernet and VGA, system restart or hangs.Even if i isolate plates same problem observed.
Please suggest me any solution for same problem .If required i can upload picture of machine.

 

[rogerynt]

How did you connect your battery or any other gnd ?

 

[vaibhav.k]

Battery is connected with floating ground.Battery charging section low side sensing.Latest observation is that on mains also there is problem.Due to repeated ESD discharge my VGA driver burned.

 

[ilikebbs]

Do you add ESD suppressor array on USB,ETHERNET and VGA interface?

 

[rikie_rizza]

I think the problem is not ESD... how can you confirm its ESD?

Some type of leakage can also cause such problem. Try to ground yourself and touch the contacts. Try to use battery but still connect the ground terminal to ground (e.g wall socket ground, or any metal object that plunge into a wall or structure).

 

[Iouri]

Even if you disconnect Mains, you still need to Earth GND connection, also make sure your monitor and verything else connected on the same grid