TPD1E10B09 ESD test fail issue

Hello,

I find it interesting that TPD1E10B09 fails to protect at 8-kV contact but PD03S090N301PT does. The enigma is because TPD1E10B09 clamps with a lower voltage than PD03S090N301PT. It's this clamping voltage that is presented to the system during an ESD strike. When I saw that the PD03S090N301PT is a Poly-TVS I knew immediately that the  clamping voltages would be high, and they are. It clamps 2A 8/20-us surge at 23V, whereas TPD1E10B09 clamps 5A 8/20-us surge at 20V. So, strictly from a clamping voltage level perspective, TPD1E10B09 presents a lot less voltage to the system during the same ESD tests.  This is why it is interesting if TPD1E10B09 fails to protect at 8-kV contact but PD03S090N301PT does.

To find the reason behind the observation, I will consider the 300-pF capacitance of PD03S090N301PT  vs. the 10-pF capacitance of  TPD1E10B09. I will also consider the response time of  < 0.5 ns for PD03S090N301PT vs. ~ 1 ns for TPD1E10B09. A common problem seen in ESD layout is having a ground scheme for the TVS which is not ideal, i.e. the path to ground has some inductance due to a poor layout. If this is the case there is often a lot of ringing of the clamping voltage during an ESD strike. If this is happening, then the  300-pF capacitance of PD03S090N301PT offers an advantage because it will suppress the ringing, and the faster response time may also help as well by being faster to clamp any overshooting voltages.

I would be certain that with a proper layout scheme, the TPD1E10B09 would protect better than than PD03S090N301PT.

Regards,