MOSFET which turns on @ 2Vgd

FDN337N has a typical threshold of .7V

** Meaningless.

It is not fully on unless the GS voltage is over 2.5 V

.... Phil

They call 'em BJTs. ;-)

What voltage is being switched? Very fine MOS can do that, but Vdss = 7V or so.

If you need more, amplify. Silicon any bigger than that doesn't offer enough transconductance. You might get there with GaN (there are some available for switching purposes), otherwise, you need more volts (amp, gate drive, charge pump..). Or a BJT, a high hFE / low Vce(sat) model of which looks like a FET with a leaky gate, very easy to drive.

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

You need say what you mean by 'fully on'? RDSon of under ten ohms? or are you looking for milli-ohms? What kind of current is being handled, what voltage drop allowed, max temp, min temp. etc etc.

piglet

Use Digikey next time. They've got the only search engine that really works.

Not from memory but from browsing Digikey :-)

Voila:

N-channel:

P-channel:

You didn't give us any desired data auch as voltage, current or channel type so I picked both.

--
Regards, Joerg 

http://www.analogconsultants.com/

1.8V okay?

You won't find MOSFETs with high Vds that will work from low Vgs.

Best regards, Spehro Pefhany

Then buy it somewhere else. It's like the Best Buy/Amazon thing.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation

Something a little beefier here:

20V part with 0.035 ohm typical Rds(on) with 1.8V drive.

Yep. Sometimes Mouser has slightly better pricing. But usually the difference is insignificant compared to all the other project costs and most of my clients prefer to just click the "order" button.

What I am noticing is that (at least in my case) the electronics biz moves away from CA and to TX. Got four clients just in Houston. They can obtain parts from Mouser much faster without running up huge rush shipping costs since Mouser is in Mansfield. So lately I ended up having to source at Mouser which is a pain because their search engine is IMHU sub-par.

--
Regards, Joerg 

http://www.analogconsultants.com/

How can you define "fully on" without knowing the drain current he needs? According to the referenced data sheet, the typical Ids is about

4.5A at 1.75Vgs. See figure 5.

I'm north of Austin and Mouser is great to order from. If I get the order in by 6pm it will show up UPS the next day. Same with TTI (bought Mouser if memory serves). I search with Digikey and have tabs open for Mouser, Avnet, TTI, Arrow and plug the part number into them. Recently I've been getting parts from Avnet (Phoenix) in 2 days, FedEx flat $8 shipping. Heilind is also a good one for me - they are in Austin. DigiKey is the slowest of them for me. Our UPS and FedEX guys know us (and the dogs) by name :)

Mouser has poor data quality. You see voltage listed as 3.3 or

3.3v or 3.3V and they all will have different parts (or zero parts). My nephew works at Mouser doing web dev. Every time I see him I give him crap about their selection tools.

--
Chisolm 
Republic of Texas

I just got in mine for a Houston client. If it wasn't for our Labrador Retrievers alerting about a delivery we would not have made the Mouser cut-off.

Same here. Two Labradors. Which can be really practical. I was urgently waiting for a client shipment this morning and the millisecond the Fedex truck turned into our street ... *WOOF* .. *WOOF* ... not one minute was lost and I had it all on the bench with cables hooked up.

He may be too young to truly understand that this costs Mouser serious business.

--
Regards, Joerg 

http://www.analogconsultants.com/

Digi-Key was slightly ahead of Mouser, I think, in giving you the order ID so somebody else could look at your cart of items. A few jobs ago, I discovered that e-mailing specs to the boss ("I need some 1000 uF caps, at least 50 volt") was unreliable. Part numbers didn't work any better. Sending the order ID so he could pull up the cart with items already in it, add whatever he needed, and place the order worked great. I think Mouser has equivalent functionality now.

I find that Mouser tends to have more selection for "power" things - big relays, gel-cell batteries, TO-3 transistors, stuff like that. Digi-Key is better at the latest microcontrollers, and things that only come as a 5000 ball BGA.

I have a copy of the Nov-Dec 1987 Digi-Key catalog. It is 108 pages, including the front and back covers. The front cover boasts "over 400 new part numbers". Not all of the part numbers end in "-ND", either.

When I was in Tulsa, you could often order UPS ground from Mouser and get it the next day. It seemed to help a little to order earlier in the day, instead of right before the UPS cutoff.

TTI has owned Mouser for at least several years. A few years back, TTI was bought by Berkshire Hathaway (Warren Buffett).

I usually only look at Digikey and Mouser, but that's because I'm usually only ordering a few parts. Avnet and Arrow seem to assume that you're ordering millions and want to have a salesdroid come by so you can haggle over the price of every 1/4 watt resistor.

The last full-line local parts distributor in Tulsa (Radio, Inc.) closed down sometime before 2008; there was still a surplus place kicking around then. Here in Kansas City there is still Electronic Supply, if you have to have it *today*.

I see this sometimes at Digi-Key too, but not as often. They ought to be able to formulate some queries like "show me tags that are applied to less than 10 parts" to find these.

Another thing that seems to trip both of them up are things like DC-DC converter bricks that have a 24 V nominal input but can work over 9 to

36 VDC - sometimes it's a tossup whether the range or the nominal input is listed.

Maybe they should do the modern thing and crowdsource it. Add a button that says "This parametric search is messed up"; you click it and get a text box to explain why. If done correctly, the trouble ticket would automatically include a copy of the search you were running, so they could see what you see.

Matt Roberds

Avnet and Arrow both do web ordering. You can order 10,50, 200, etc or full reels on some items. Others are reel only. I order uC from Avnet, they have the best price on some of the ones I use. For resistors I just get the reel now. I can get a 5K reel from TTI for $11.50. With shipping cost these days it is worth it to not have to re-order very often. Avnet web sales are also good with the RFQ. I needed some dual RJ45s. Did a RFQ (web) for 70 (2 boxes). Avnet beat everyone else by over a $1/ea. And the offer was any quantity (1 to N) for that same price. No phone calls, just a email back with the details.

[snip]

Mouser now has a "See an error?" button when you click the item but I dont think they have a search error button. I just email my nephew when I find something. There was a DB15 that would show up if you entered the part number but not on a search. DigiKey still seems to have the best search engine.

--
Chisolm 
Republic of Texas

4 Border Collies. Their favorite is USPS. One of the delivery guys leaves them treats in the mail box. You know when he is bringing the mail, they recognize his vehicle coming up the street. No matter who delivers they always want to sniff the mail looking for a possible treat.

Like most his age, it's a job and that's all. It's always the data entry folks problem. I would have thought the manufactures would have some type of system now to supply the distributors with all the part parameters in some type of machine readable form.

--
Chisolm 
Republic of Texas

There are two ways to fix the shipping cost problem. One is to not require fast shipping and the other is to use Priority mail by USPS. UPS or Fedex ground takes four days from Digikey here, but Priority mail is only two days. I even got a shipment from California (I'm east coast) in two days by Priority mail. That's impressive. :)

--

Rick

** Easy - it's when the "on resistance" reaches its minimum.

Quoting the threshold figure like you did is total bollocks.

..... Phil

which turns fully on when Vgd = 2V (or less)

Do you mean Vgs=2V?

[snip>