piclist 2002\09\23\090350a >
Thread: 2-tran SMPS 5v reg now 90% efficicient!
www.piclist.com/techref/index.htm?key=tran+smps+reg+efficicient
picon face BY : Morgan Olsson email (remove spam text)



Roman Black wrote:
>Morgan Olsson wrote:

>Yes, apart from you need 2 emitter resistors (not base)
>as base resistors will have the wrong effect. :o)

No, as long as you calculate the base drive to worst case hFE there is no problem, as this is switching -not linear- operation.

Emitter resistors will loose more power / total efficiency without gaining anything in this case.

Btw, paralleling mosfets is generally no problam as their ON-resistance increase for higher temp, balancing it more equal.  But as ON-resistance is not identical between two of the same kind, you can´t double the load for double mosfets.

And, you can in most cases eliminate Rc if you use Mosfet, as they usually can take up to 20 or 30 V gate drive.

Regarding display in Opera:
It seems Opera thinks you told it to wrap, or don´t understand your type of manual newlines.  (it autowraps all paragraphs on that page) I know too little to evaluate if it is your page, or Opera that don´t comply to W3C.
Might be syntactic; Opera is a little picky on syntax while other browsers guess what the user meant.  Try validating at i.e http://validator.w3.org/

/Morgan

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Subject (change) 2-tran SMPS 5v reg now 90% efficicient!

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