Pulling current through a FET while it's turning off

Hello,

I'm trying to figure out how much current I can pull through a FET while it s turning off... basically, how fast I have to turn it off if I have it hoo ked up to a constant current load so that the load doesn't kill my part whi le it goes through its resistance region... what information on the datashe et should I be looking at to figure this out?

I'm guessing it's the power dissipation rating, but I'm not sure....

Here's the FET I'm using

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much thanks!

Reply to
panfilero
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You'll have to keep your eye on figure 2, the safe operating area or SOA. Make sure you never exceed the limits. For example, while at 200V Vds it can take 20A for 1mseec, but if it takes 10msec then only 7A.

De nada :-)

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Oh, and that's for single pulse or "once in a blue moon". If such situations happen in rapid succession you need to also get into figure 3 and avoid death local excessive local heating.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

We're using one NXP D2PAK that will dissipate 20 kilowatts for a microsecond, basically is Vds-max * Id-max simultaneously.

That's the one I'm SOAR protecting with my little analog computer!

Interestingly, many of the fets with good SOAR holdup are oldish parts.

--
John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
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Reply to
John Larkin

turning off... basically, how fast I have to turn it off if I have it hooked up to a constant current load so that the load doesn't kill my part while it goes through its resistance region... what information on the datasheet should I be looking at to figure this out?

That's a nice part.

to bad the gate cap is so high but I guess it would depend on the application at hand.

It really depends on your application, I can see that being used in auto applications incase of load dumps etc.

Personally my self, I wouldn't want a supper fast switching speed, with high voltage on drain side, the miller effects could prove to be interesting.

Jamie

Reply to
Jamie

turning off... basically, how fast I have to turn it off if I have it hooked up to a constant current load so that the load doesn't kill my part while it goes through its resistance region... what information on the datasheet should I be looking at to figure this out?

It is a brute, but the q1 price is $33!

--
John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
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Reply to
John Larkin

le its turning off... basically, how fast I have to turn it off if I have i t hooked up to a constant current load so that the load doesn't kill my par t while it goes through its resistance region... what information on the da tasheet should I be looking at to figure this out?

681.pdf

I have 400pcs of this one lying around:

ST STW45NM60 (650V 90mOhm)

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Anyone want them for a bargain price? (sorry for the sales pitch)

Regards

Reply to
Klaus Kragelund

I'm trying to figure out how much current I can pull through a FET while its turning off... basically, how fast I have to turn it off if I have it hooked up to a constant current load so that the load doesn't kill my part while it goes through its resistance region... what information on the datasheet should I be looking at to figure this out?

I'm guessing it's the power dissipation rating, but I'm not sure....

Here's the FET I'm using

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much thanks!

snipped-for-privacy@gmail.com

Reply to
<dankatewiiliams

its turning off... basically, how fast I have to turn it off if I have it hooked up to a constant current load so that the load doesn't kill my part while it goes through its resistance region... what information on the datasheet should I be looking at to figure this out?

1.pdf

That is just not enough information. Where might the current alternatively go to and what is the compliance of the current source? Is there any energy transfer capacitors or inductors involved?

?-)

Reply to
josephkk

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