RE: Jimmy's DRSSTC 2

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

At 08:14 AM 10/1/2004 -0600, you wrote:
>Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com>
> >The results of the thermal simulation make it look too easy. I'd like
> >someone to check my numbers. I really hope it's right.
>
>They certainly do look suspiciously... good :P I've been doing calculations
>on some similar 300A 1200V bricks. (the Semikron SKM300GB123D)  The maximum
>pulse rating on these IGBTs is 600A for 1ms, and the datasheet says the
>pulse width is limited by junction temperature.
>
>That suggests that 600A for 1ms will raise the junction temperature from
>25'C to 125'C. (The fact that the pulse rating goes down to 440A at 80'C
>case temperature reinforces this hypothesis)

Does the mfr publish a thermal model for the device... Usually, they'll 
give you a 2 or 3 node model.  Die mass: Theta jc: case mass: theta cs

If you know these masses and thermal resistances, it's just like a cascaded 
RC network, and you can calculate the time constants.