Power Schottky has low Vf

[cupoftea]

Hi,
This Schottky (STPS41H100)

https://www.st.com/resource/en/datasheet/stps41h100c.pdf

...is measuring 0.1V in forward direction, and open in other. 0.1V seems very low?

With the same meter, the Boost PFC diode measures 0.35V. (Boost PFC diode actually measures 0.35V in both directions, but i guess this is because the meter can see the Boost fet diode through the output caps. Boost diode is SDP06S60)

SDP06S60 datasheet

https://www.infineon.com/dgdl/SDP_T06S60_Rev.2.1.pdf?folderId=db3a304412b407950112b408e8c90004&fileId=db3a304412b407950112b439cfc26eec

 

[betwixt]

Its silicon carbide, that is more normal for that structure.

Brian.

 

[KlausST]

Hi,

It seems you measure the boost PFC diode "in circuit".
This is not recommended.

I don´t know how you measurend the STPS diode. In ciruite or bare? At what current?

Klaus

 

[cupoftea]

I don´t know how you measurend the STPS diode. In ciruite or bare? At what current?

Thanks, i measured the STPS diode with it desoldered from circuit...just measured it with standard DMM (iso-TECH IDM 71)

 

[crutschow]

Thanks, i measured the STPS diode with it desoldered from circuit...just measured it with standard DMM (iso-TECH IDM 71)

How did you measure the diode forward voltage with the DMM?
What current was going through the diode?

 

[dick_freebird]

Some DMMs offer a diode / transistor test using
the same (or different tap, of) resistance current-
forcing.

This forced current tends to be suited to small
signal devices and will likely read low, relative
to spec'd Vf param's spec'd forced current
(density). It's absolutely certain that a DMM will
not be forcing the 20A spec test condition for
the Vf param, in the datasheet Table 3, off its
9V battery. Single digit mA, more likely.

If I eyeball-extrapolate the Figure 7 I-V curve to
10mA IF, 0.1V sure looks likely; reasonable, even.