Why clamping voltage is not given for some ESD diodes

[newbie_hs]

I was comparing two ESD diodes.Their P/N's are PESD5V0S1BL,315 and

PESD5V0U1BL,315.

If you check the datasheet of both parts you can see that clamping voltage is specified for PESD5V0S1BL,315 and they did not mention any clamping voltage for PESD5V0U1BL,315.



May I know why it is like that.

 

[FvM]

The datasheet waveform suggests similar clamping voltages as for the first diode. The question is, what does it matter for your design if you had a clamping voltage spec of 16 versus 10V @10 A? Both values are far beyond maximum ratings of the protected chip.

External ESD protection works in combination with internal protection circuit, extending ESD rating from 1 or 2 kV to e.g. 8 or 16 kV. Protection has to be verified in the final layout, it depends on many parameters like parasitic inductance.