Re: DC/DC powver converter, 500W


Terry Given wrote:
Tim Williams wrote:
"linnix" <me@xxxxxxxxxxxxxxxxxx> wrote in message
news:1142808918.692376.28710@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Yes, voltage is low, but current is high. For 20A or so, you need to
switch at very low duty cycle and spread across many MOSFETs.
I am not sure how to do that with LM339.


nah, 20A is bugger all.

20A output. 24V drop across 5mR would give a lot more than 400A.
The trick is to turn it off before it gets more than 880A.

just use a decent FET - at 5mR, 400A gives a
measly 2W dissipation. a few SO-8 FETs would do the trick, sans heatsink ;)

That's certainly not for a SO-8.

For example, the ST250NS10 (ISOTOP power pak), can draw 220A.
You can pulsed it at 880A, but less than 10% duty cycle.

I would use several of them to get a decent output power.



Well, I meant the controller part, obviously...

Switching 20A or so with LM339s would need about a thousand of them, a
slight excess from my estimate. ;-)

Tim

now now Tim, use the worst-case spec of 6mA....3332 of them, so 833
packages :)

Cheers
Terry

.

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