Hi all,

I was told by OEM company to find a junction temperature of a schottky diode at negative temperautre.

I looked through different diode, but I was not able to find a single diode that shows the forward voltage behavior at negatove temperature.

Usually shows as low as 25 or 0 degree.
Although most components have a temp range from -55 to 150 degree, but since there is no forward voltage shown in negative temp range I cant find junction temperature..

Must be a reason for it.. maybe below 25 degree is the same all the way..?

Can anybody help??

Thanks in advance.

Part numbers:
STPS1L40-Y
SS14FL
NRVB140ESF

 

https://www.google.com/url?sa=t&rct...f?sequence=1&usg=AOvVaw1cI1_1e7FcTpBaEyN9kKNK

Regards, Dana.

 

Basically the forward voltage drop is fairly linear with temperature so you can use the change in voltage with temperature determined at room ambient to calculate an approximate value for the forward voltage at low temperatures.
But if you need good accuracy, there's no substitute for measuring the actual device at the desired low temperature and forward current.

 

Why would an OEM company tell you to do this?

If you Google something like: diode forward voltage as function of temperature

you get LOTS of hits.

 

Why would an OEM company tell you to do this?

If you Google something like: diode forward voltage as function of temperature

you get LOTS of hits.

I guess it's because we don't live in the ideal world. Some cases, voltage drop at the power bus input due to the temperature variation is critical.

If you are referring a forward diode voltage VS temperature relationship that you would find from the college text book, yes there are tones. However, a current industrial diode is different from what you would seen from the text book. If you use a textbook diode equation, you'd never have same IV plot that shown in datasheets. It would be great, if you can reply me with the link you found. Otherwise I will contact FAE of manufacture..

 

Basically the forward voltage drop is fairly linear with temperature so you can use the change in voltage with temperature determined at room ambient to calculate an approximate value for the forward voltage at low temperatures.
But if you need good accuracy, there's no substitute for measuring the actual device at the desired low temperature and forward current.

I guess that would be the easiest approach.. But, I guess at this point, reaching out FAE would be the best option.

 

I guess it's because we don't live in the ideal world. Some cases, voltage drop at the power bus input due to the temperature variation is critical.

If you are referring a forward diode voltage VS temperature relationship that you would find from the college text book, yes there are tones. However, a current industrial diode is different from what you would seen from the text book. If you use a textbook diode equation, you'd never have same IV plot that shown in datasheets. It would be great, if you can reply me with the link you found. Otherwise I will contact FAE of manufacture..

If the exact relationship is that critical, then definitely get the information for THAT model diode from the manufacturer.

 

I guess that would be the easiest approach.. But, I guess at this point, reaching out FAE would be the best option.

Search on MOSFET series reverse voltage protection.

Connect the MOSFET in series with the supply so the body diode would conduct - bias the gate to enhance the channel and it conducts one way with less Vf than a diode.