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Old 14th March 2005, 09:35 AM   #1
Previously: Kuei Yang Wang
 
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Default Need readily available High Voltage, Low Capacitance FET

Konnichiwa,

For a specific application I need a FET with 400 - 600V Voltage handeling and very low input capacitance. Preferably sourcable from Digi Key, Mouser, Farnell/Newark or RS Component.

Arigatou gozaimas

Sayonara
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Old 14th March 2005, 09:50 AM   #2
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Is a cascode ruled out in your application ?
I ask because both - FETs with high Vds and high input capacitance and FETs with low Vds and low input capacitance are readily available but maybe not the device that you are lookin for.

But maybe you could be a little more specific about the other specs you are looking for (Rdson, PD, Ids, ......).

Regards

Charles
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Old 14th March 2005, 10:00 AM   #3
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IRF710 looks like a good choice, one of the lowest Ciss I have come across, available from RS...
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Old 14th March 2005, 10:04 AM   #4
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Konnichiwa,

Quote:
Originally posted by phase_accurate
Is a cascode ruled out in your application ?
Not absolutely, but simplicity dictates to avoid it if possible.

Quote:
Originally posted by phase_accurate
But maybe you could be a little more specific about the other specs you are looking for (Rdson, PD, Ids, ......).
A few Watt Dissipation and < 1A Draincurrent are fine, Rdson is uncritical, as is pretty much anything else. The Voltage and Capacitance parameters are critical. An insulated case would be nice, but is not neccesary.

Sayonara
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Old 14th March 2005, 10:08 AM   #5
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Konnichiwa,

Quote:
Originally posted by richie00boy
IRF710 looks like a good choice, one of the lowest Ciss I have come across, available from RS...
Yes, IRF710 is a standby choice, but it really has still too much capacitance, plus it's supposedly discontinued.

I have come across lower capacitance types in Toshiba and SGS Catalogues, but they are not readily available from the usual sources and I don't want to buy 1000pcs.

Sayonara
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Old 14th March 2005, 10:39 AM   #6
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I have found that ST produce clones of a lot of the IR parts and often the have even lower Ciss than the original IR part. Rapid Electronics have a small range (but unfortunately not the 710 it seems) and will sell small quantities to hobbyists and the like.
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Old 14th March 2005, 11:14 AM   #7
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Unfortunately the IRF710 seems to be the IR model with the lowest input capacitance in the 400 Volts range. And IR Mosfets are the most widespread ones amongst the average distributors.

So there are obviously only those three choices:

1.) Try to get a source for SGS or Toshiba that sells in low quantities.

2.) Use one of the IRF types and arrange your driver accordingly.

3.) Use a cascode consisting of a IRF71x and a smaller FET (which is still not easily obtained with an Ciss of less than 150 pF).

Regards

Charles
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Old 14th March 2005, 11:23 AM   #8
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What is "very low input capacitance"? Maybe the only way is to use a cascode?

What is you application?
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Old 14th March 2005, 01:52 PM   #9
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Zetex second sources Supertex, you can order 450 Vds ZVN0545 and ZVP0545 thru DigiKey - Supertex is carried by some major dist houses, 500 V parts are available

ZVN0545 in sot-223 can be handled like a thru-hole - has ~.1" lead spacing, and metal tab that could be soldered to a Cu flag for 2W P without going the full smt route - a few could be paralleled for some power margin
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Old 14th March 2005, 02:37 PM   #10
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STW11NB80? Idunno... works for me, datasheet says "low capacitance"...

Click the image to open in full size.
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