Alternative to IRFZ40
Michael Michailidis
an equivelant of the IRFZ40 power MOS FET? I am trying to find this in
Britain but it seems that it is discontinued.
TIA
Michael
Terry Pinnell
Found one US source, FWIW.
http://debcoelectronics.com/catpages/productIRFZ40.html
In Stock Quantity: 1
Price: $1.29
But from quick look at data sheet at
http://www.angliac.com/st/data_from_st/3019.pdf
I'd guess that many other TO-220, high current, fast switching MOSFETs
could be safely substituted.
Terry Pinnell
Hobbyist, West Sussex, UK
Fritz Schlunder
"Michael Michailidis" <news...@blueyonder.co.uk> wrote in message
news:asu6q6$uluti$1...@ID-160639.news.dfncis.de...
AFAIK, the original IRFZ40 is extremely similar to the original IRFZ44
(except the IRFZ44 has a 60V maximum drain-source rating versus the IRFZ40's
meager 50V). You may be able to find the original IRFZ44 floating around,
but they have since been discontinued as well (at least by International
Rectifier, other manufacturers may still be making their own flavors of
them). International Rectifier recently replaced the IRFZ44 with a slew of
new parts such as the:
IRFZ44V
IRFZ44E
IRFZ44R
IRFZ44N
Which are all optimized to enhance certain properties over others. The
IRFZ44R is specifically designed as a drop in replacement for the original
IRFZ44 in any application including linear amplifier uses like audio
amplifiers, however the other IRFZ44 variants offer superior performance to
the original IRFZ44 in many other applications.
Get the datasheets for all of them at International Rectifier's website:
www.irf.com
If you are using this IRFZ40 in an audio amplifier or similar amplifier that
relies on the device's high power dissipation and specific transconductance
figures, then it is probably safest to replace it with the IRFZ44R.
Otherwise if this is a general application or otherwise used as a switching
element you might try using a different one like the IRFZ44N.
Both the IRFZ44N and IRFZ44R are available from Digikey (www.digikey.com).
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Gibbo
I don't have my data books handy but I seem to remember the IRFZ40 being
*stupidly* fast compared to the IRFZ44. Something like 85nS compared to 300nS.
Don't quote me on that. Even the BUZ11 won't be fast enough for that if it's
being used at high speed. I don't think the equivalent books list a direct
replacement for the IRFZ40, so it's gonna be a case of deciding which
parameters are important.
Gibbo
Fritz Schlunder
"Gibbo" <chrisgib...@aol.comma> wrote in message
news:20021208165552...@mb-ml.aol.com...
Well I don't know about that. I don't have the original IRFZ40 datasheets
by International Rectifier, but assuming the ST Microelectronics one is
about the same (which Terry Pinnell was good enough to post), we can compare
the gate charge versus gate-source voltage curves on the IRFZ40 and new
IRFZ44R datasheets:
IRFZ40: http://www.angliac.com/st/data_from_st/3019.pdf
IRFZ44R: http://www.irf.com/product-info/datasheets/data/irfz44r.pdf
When we do this comparison we notice that they are similar, but the IRFZ44R
actually appears like it should be a little bit faster than the IRFZ40. The
plateau region (where MOSFET switching actually occurs) is not as long on
the IRFZ44R which suggests the IRFZ44R should have a faster rise and fall
time (for the same gate drive configuration, IE, the same series gate
resistance of the driver). From looking at these graphs we also notice the
total gate charge at 10V gate-source is smaller on the IRFZ44R (~42nC)
compared to the IRFZ40 (~50nC). Also, the IRFZ44R has the plateau region
placed closer to the 5V (middle point for 10V gate drive) point which would
suggest a somewhat more balanced switch on and off performance compared to
the IRFZ40. Indeed there exists slight differences in the switching
characteristics between the IRFZ40 and IRFZ44R, however as far as I can tell
the IRFZ44R is probably going to be the slighly faster one.
With that said, perhaps it isn't really all that important anyways. The ST
Microelectronics version of the IRFZ40 is readily available from Mouser
(www.mouser.com). They seem to have over 800 in stock at the momement.
Gibbo
[snip]
Gibbo wrote:
It seems we're both right. Mooching around I found the following..........
IRFZ40 rise time 110nS
IRFZ44 rise time 280nS
IRFZ44N rise time 60nS
IRFZ44R rise time 110nS
Fall time and turn on/off delays are all approximately pro rata. Seems the
original IRFZ44 was a bit sluggish (though there's nothing in the data sheets
to indicate why there's such a *huge* difference) and the later ones (ie suffux
R, N etc etc) are all much faster.
On that basis either of them would do whatever the circumstances. I think the
OP is in the UK. IRFZ44Ns are available easily here. Not checked the R suffix.
Gibbo