Looking for drain-/source-swapped P-channel FET 1

[MacGyverS2000]

Looking for a P-channel FET in a SOT-23 package that has the drain and source pins swapped from the industry standard. Does not need to handle much power or voltage (5V @ 1mA).

I know such a creature exists, but finding one when you need it is (so far) impossible...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

"...P-channel FET....SOT-23....drain and source pins swapped..."

My Google-fu has failed to find anything.

Worst comes to worse, there are those companies that make the tiny PCB-based chip adapters. They typically offer custom items as may be required. You'd install a "normal" industry standard FET on the adapter, and the adapter would fit straight onto the reversed pin arrangement on the main PCB. Nobody misses lunch.

I've seen their products (on the 'net) that performed much more difficult miracles than just swapping two pins on a SOT-23, so I'm fairly sure this would be trivial for them.

Good luck.

 

[IRstuff]

I'm more curious about WHY.

JFET or MOSFET?

low voltage, so no funky drain diffusion?

Retrofit or existing part?

Body tied to source?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[sreid]

Is it a P channel J-FET and what's the pinout?

 

[benta]

If it's a MOSFET, the body diode is a problem.
For a JFET, just operate it in reverse, they're not picky.

 

[itsmoked]

If it's just a few, hand solder on the part upside down.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

No longer needed. <sigh> On second review, the circuit designed was borked from the get-go and would have completely failed to do what I wanted with a flipped PFET... as it was, the body diode was allowing it to work in a limited fashion. I replaced with an NFET and sucked up the voltage loss.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[zappedagain]

"the body diode was allowing it to work in a limited fashion" - that's a neat trick. I see LT does that in their LT4321 active PoE Bridge. While things are starting up and low power the current path is through the body diodes. Once things get started the opposite FETs on the bridge turn on and effectively short out the diodes to reduce the power dissipation. Nifty!

Z

 

[MacGyverS2000]

I've used the body diodes before. I may have told this story before, so apologies if it's a repeat...

Many moons ago I worked in an area where the electronics were treated roughly in the field <shock, awe, dismay>. Wall warts were commonly lost, leading to last-minute trips to Radio Shack to purchase replacements. Since polarity couldn't be guaranteed on the barrel jacks, I used four FETS in a bridge-like configuration that straightened out the polarity, regardless of what was used. Two FETS operated as normal, two had their body diodes used... which set did which job depended upon the polarity of the barrel jack. Worked a treat and saved many a frustrated field tech's sanity (and mine when stuff came back with the magic smoke let out).

Dan - Owner

http://www.Hi-TecDesigns.com