IR is insane

No, no, no. Experience is the worst teacher. Thinking and math rule; experience only reminds you of things that shouldn't be ignored for analysis, not of actual expected results. Experience must be constantly questioned because things keep changing.

I know it will explode at 340 amps, and even at 190, unless the connections and cooling are done under some insane laboratory fixturing that is absurd for a DPAK part on a real board.

No, I know the literature is absurd and deliberately deceptive.

There are penty of perfectly good, and cheaper, mosfets around, from people who are not blatantly dishonest. I'll buy them.

Rant all you want. If you want to use DPAKS at 195 amps and 375 watts, go for it.

John

think this has part of the long explanation as to how the come up with the numbers

-Lasse

Chilled water to cool a tiny surface-mount package?

This uses TO247 packages, clamped to a gold-plated, water-cooled copper block, at those sorts of power levels. But the lead current is a lot lower than 340 amps.

John

John Larkin: Pomposity at its glorious extreme. ...Jim Thompson

Quote "To actually utilize our parts in an application that targeted currents at the level of the ultimate current would likely be costly and impractical. Nucleated boiling is an expensive and tricky proposition."

... and ...

Quote "The heritage fleet of power MOSFET products has been rated via the classic method as described by equation 1. Those ratings fall on a very conservative engineering side. Newer, advanced products like the expanding suite of IR Trench products will begin carrying the new ultimate current limits, if appropriate."

Why does this remind me of the real estate market?

I want heritage datasheets :-)

It seems "normal" these days. Take a look at this datasheet as an example, just came up in Raveninghorde's thread:

Here you have a driver that is touted as 2A, 3A peak. The figures in the datasheet are of little use, not output loading curves and the table data has a wee remark that the device sits at VDD/2 when sinking 2.5A, sourcing is even worse. Easily overlooked. A young engineer might exclaim "hooray!" and design it in, only to have it almost unsolder itself or going *PHUT*. Then after a few experiences like that he might think that analog is a frustrating business to be in and move on to other fields :-(

"Modern" datasheets can often only be used when reading between the lines and applying a healthy marketing hype correction factor.

The IR testing context isn't 100% clear to me, but using boiling liquid may be the way they get the DPAK source lead to not melt at their specified currents. Ditto not melting their solder joints to a pc board.

John

Sanity, at last!

John

...in that case, i have some #30 wire rated at 1,000 amps and will guarantee it or double your money back!

You mean going out of business like Signetics?

John

PC board?? Tack 24AWG wires onto it and sink the whole thing into the refrigerant. PC boards are excellent insulators in comparison.

Tim

Anybody here remember the Signetics WOM? As I recall it was intro'd back in 1972 about this time of year. Maybe IR is following suit? Art

Nope. Intro'ing a product like the WOM. Art

Something that only a total techno-idiot would declare.