while looking at datasheets for clamping schottky diodes, I noticed that the values that manufacturers state in their tables ("Pulse test: tp < 300 µs; delta < 0.02.") are different from the values you get out of the diagrams.

NXP BAT54 for example: https://assets.nexperia.com/documents/data-sheet/BAT54_SER.pdf Table 7 vs. Figure 1 on page 4

Table: ("Pulse test: tp < 300 µs; delta < 0.02.")
If 0.1mA Uf 240mV
If 1mA Uf 320mV
If 10mA Uf 400mV

Diagram @25°C: (roughly)
If 0.1mA Uf 160mV
If 1mA Uf 210mV
If 10mA Uf 300mV

What causes this difference? What do they perform pulse tests for?

And if I plan on using the diode for a constant overvoltage condition (to protect an analog input), do I use the diagram values rather than the pulse values?


The pulse values are maximum values. The diagram shows typical values.

Typical values will always be lower than maximum, more or less by definition.

  • \$\begingroup\$ I'd just add that if in @Winter's design something changes upon a few hundred millivolt forward drop change, that design have to be reviewed \$\endgroup\$ – carloc Mar 10 at 7:49

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