Schottky barrier diodes

[vincentp]

Hi all,

Could anyone remind me what is the purpose of such parts ? Especially the reverse caracteristic ?....am forgetting something here...

 

[IRstuff]

HAve you done a websearch?

From what I recall:
> fast, having low storage time
> low forward voltage, thus making Schottky TTL possible
> soft reverse characteristics

TTFN

 

[vincentp]

yeah, really a websearch is THE thing to do. I got some info.

Many thanks for your prompt response.

Cheers,
V.

 

[vincentp]

Another thing though...

They are usually quoted at Tj=+125C MAX. But further down in the datasheets tests are shown at Tamb=+125C.

How do we determine the Max T ambient they can at ?

Cheers,
V.

 

[logbook]

Junction temperature is always the key limit. The maximum ambient is worked out from the maximum junction temperature, the power dissipated, and the thermal resistance from junction to ambient.

Suppose the device is dissipating 1W. If the thermal resistance from junction to ambient is 10degC/W, the junction will be 10degC hotter than the ambient, making the maximum ambient 115degcC if the junction has to be kept to 125degC. It is just as simple as this.

If the device were to be dissipating a negligible amount of power, it would be able to run to the full 125degC ambient. You see this expressed as power derating curves against ambient temperature.

 

[sreid]

The reverse voltage is almost always quite low (and the leakage gets much worse with temperature). But they are great for, say, free wheeling diodes in switching power supplies.