View Full Version : .20 cent mosfets with no data sheet

02-16-2007, 01:50 AM
I can't find a data sheet for this part and digikey has 15,000 of them. I bought a few but I have tried all the usual searches to find it.

Digikey # 64-8037PBFCT-ND
MFG # 64-8037PBF (international rectifier)

Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Phil Pilgrim (PhiPi)
02-16-2007, 02:11 AM
Yeah, that number comes up blank on the manufacturer's website. I would call DigiKey to see if that's the right manufacturer's part no. Most International Rectifier part numbers start with "IR".


02-16-2007, 03:23 AM
Hi Phil, The part that I think will work the best here for the LUXEON III 1500mA LEDS is digikey# 497-4525-1-ND up to 6.5AMPS

It has at 5V .06 OHMS . That is 60 milliohms correct? It is the smallest RDS(on) resistance mosfet I could find.
The Gate Threshold is a volt lower but that is fine for this application.

This one: 479-3309-1-ND
has some nice features: Current limiting, thermal shutdown, short circuit protection and some interesting DIAGNOSTIC FEEDBACK
I may use this in my stage lighting product. I may be using a 36V transformer with those.

Going through the list of fets that come in sot-223 package. I bought 10 of each of these as well but I have not read the datasheets in detail yet to compare them.


And just because I like to buy something extra that I have no use for and can't even imagine a use for since I have some empty drawers.

CLA220-ND a 415V

The Drain Current specs though I don't understand , conditions of VDS=50V is 5ma current maximum, and at 5V is 130ma minimum.
probably never use it but mostly because i don't understand its specs.

I would appreciate any thoughts on differences in these mosfets generally, historically or specifics.

Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

02-16-2007, 09:06 AM
Here is a picture of the mosfet chip.
The digikey part# is 64-8037PBFCT-ND and is $1.25 qty 1

I searched findchips , the lowest price I found qty 10,000 is 70 cents so 290 cents is 1/3 of that no qty limit
They have 5222 in stock so its a good buy. I don't know why they are marked that way though.
I tested the fet vs the irfl1110 , The current went from 650mA to 750mA through that fet and the specs show a .5ohm to .2ohm difference in the resistance of the chip.

This fet says it has a .20 ohm resistance RDS(on)

To test that I measured the voltages across the resistor and LED

Running the LED just through the resistor is 1180mA with a 1.2 Ohm resistor

My Voltage in is 4.6V

Measured 1.76V across the resistor

Measured 2.84V across the LED

2.84 + 1.76= 4.6

Now I put the fet in and I get: 750mA current

0.8 Across the resistor
2.5 across the LED
1.3 across the FET

So this fet is pulling (1.3 x .750) = .975 watts

================================================== =============

Now I tested this fet : Digikey# 497-425-1-ND
MFG Part STN4NF03L price $1.30
6.5A max current

Big difference. RDS(on) is specified on the datasheet as <0.05

I get 1150 mA just 10 mA across the fet and it doesn't even get warm about .073V across the fet

================================================== ==============

Digikey# 497-3309-1-ND price $1.30

This chip has a lower Amp Rating 3.5A but it has some nice features, thermal shutdown and short circuit protection are two of them.

I get 1130ma through the LED using this Mosfet

================================================== ==============

497-3177-1-ND 60V 4Amp Price .97cents

I get 1140mA through this one.

================================================== ===============

Digikey# 497-4764-1-nd 60V 4amp price .59 cents

1110ma through this one


Digikey# IRLL024Z-ND 55V 5 Amp price .78 cents

1150ma through this one

Digikey# IRLL024N-ND 55V 3.1 Amp price .64 cents

1150ma through this one

So I learned about RDS(on) resistance because I needed something better than what I had.
I paid $1.05 each qty 100 for the IRFL110 and the .20 cent fet was better (not by much) but all of the others I just tested are much better choices. I think the rule of thumb of 2x the rating must be true as the IRLF110 is only a 1.5A but at 100C it drops to .96 and that's when pushing with 10V.

Now I can finish my LUXEON III color test board with 8 different colors and do some thermal testing.

Thanks to Phil for the tip on RDS(on) resistance something I had never looked at before after all, I'm not an EE but I play one when I get off work.

Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

02-16-2007, 05:56 PM
Have you considered the IRF7311?
(Two N-Channel MOSFETs in a single SO-8 package)

It's listed with .029 Ohm.

Don't visit my new website...

02-16-2007, 10:27 PM
Here is a good chip search site http://www.findchips.com/

lets see what this does... KA BOOM (note to self do not cross red and black)

Beau Schwabe
02-17-2007, 12:09 AM

try... (http://pdf1.alldatasheet.com/datasheet-pdf/view/68466/IRF/IRFL4310/datasheet.pdf)


Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 2/16/2007 4:14:12 PM GMT

02-17-2007, 12:58 AM
After I got the chip I did find the data sheet on that site Beau. The original problem was that digikey did not list it with that part number and did not link a data sheet. What I am saying is it is a good price for that chip if you don't need low RDS resistance.

Gadget, that's a nice chip you point out. Won't work on this though because the boards are already made using a sot-223 layout.

It's really interesting though how critical some specifications on chips that do the same basic thing come into play for different circuits. I never realized how much power difference there could be for a resistance that is only 1/2 ohm or 1/10 of an ohm when one typically thinks of a 100 ohm resistor that could be 99 ohms or 101 ohms and makes no difference in the circuit.

Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

02-17-2007, 06:31 AM

Thanks for the great information. What is the power rating on your 1.2 ohm resistors? Do you have a part number? I have been considering playing around with some of those high power Luxeons. Please keep us posted on the results of your thermal testing.


Chris I.