On Mon, Dec 15, 2003 at 05:44:19AM -0800, Brad O'Dell enlightened us thusly
> Hello everybody,
> I was repairing a socket 370 motherboard and needed to replace a noticeably damaged
> Harris HUF76121D3S (part is branded 76121D, also Fairchild has this part). All I
> have easy access to is a RFP30N06LE. Will this be a suitable replacement besides
> the package style (TO-252AA versus TO-220AB)?
>
> starter data:
> both are N-channel enhancement mode logic level MOSFETs
> replacement has higher voltage rating (Vdss and Vdgr 60V vs. 30V)
> replacement has higher current rating (Id 30A vs. 20A)
> replacement seems to be faster
> however, drain-to-source ON resistance is more with replacement (Rds(ON) max.
> .047ohm vs. .030ohm). Would this significantly affect circuit operation? Also the
> HUF76121 Rds(on) was rated for the part maximum current of 20A, whereas the RFP30N06
> Rds(on) was rated for that part's maximum current of 30A. How would I recalculate
> the RFP device's Rds(on) with the lower current of 20A that will be used?
>
The rule of thumb is to replace with better, and replace all together in
a current sharing arrangement.
I am expert at breaking this rule ;-). I would not worry. Swap away. I
can't imagine any problems resulting from extra heat, as you have a
bigger package, right? Not many designers make use of propogation time
in switching circuits. Don't recalculate the RFP device's specs
whatever you do, as you will only worry yourself :-).
The question I am asking is - why did the first one die? what killed it?
--
With best Regards,
Declan Moriarty.
--
Author: Declan Moriarty
INET: [EMAIL PROTECTED]
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