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Sci.Electronics.Basics -> Mosfet
There are 5 messages in this thread.
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Author: Roger DewhurstDate: 17:44 15-10-07
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How are the pins of a mosfet identified please.
The project requires a 45V/16A Schottky diode or similar. I cannot find a
supplier. What is special about a Schottky diode? Can I use smaller diodes
wired in parallel?
R
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Author: Tim WescottDate: 18:15 15-10-07
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Roger Dewhurst wrote:
> How are the pins of a mosfet identified please.
>
> The project requires a 45V/16A Schottky diode or similar. I cannot find a
> supplier. What is special about a Schottky diode? Can I use smaller diodes
> wired in parallel?
>
A MOSFET has a source, drain and gate. To identify the pins on a given
part you need to look at a data sheet. There's typically one common way
of connecting them (e.g. a TO-220 package almost always puts the drain
on the middle pin and the tab, for heat sinking), but it's not universal.
Shottkey diodes are fast, and they tend to have a lower forward drop for
the current than regular silicon diodes. They're also more expensive
and hard to get in high reverse-voltage ratings, but you can't have
everything.
45V/16A is one honkin' big diode! You could parallel multiple lower
current diodes if you wired a small resistor in series with each one to
insure current balancing, but you may run into other problems doing
that. Perhaps you could post the part number of the required diode and
someone here could help you find it.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
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Author: Roger DewhurstDate: 19:43 15-10-07
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"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:p7OdnTDQ1NJ1eI7anZ2dnUVZ_hSdnZ2d@web-ster.com...
> Roger Dewhurst wrote:
>> How are the pins of a mosfet identified please.
>>
>> The project requires a 45V/16A Schottky diode or similar. I cannot find
>> a supplier. What is special about a Schottky diode? Can I use smaller
>> diodes wired in parallel?
>>
> A MOSFET has a source, drain and gate. To identify the pins on a given
> part you need to look at a data sheet. There's typically one common way
> of connecting them (e.g. a TO-220 package almost always puts the drain on
> the middle pin and the tab, for heat sinking), but it's not universal.
Thanks. I have got the data sheet now.
>
> Shottkey diodes are fast, and they tend to have a lower forward drop for
> the current than regular silicon diodes. They're also more expensive and
> hard to get in high reverse-voltage ratings, but you can't have
> everything.
>
> 45V/16A is one honkin' big diode! You could parallel multiple lower
> current diodes if you wired a small resistor in series with each one to
> insure current balancing, but you may run into other problems doing that.
> Perhaps you could post the part number of the required diode and someone
> here could help you find it.
Can I use one half of a MBR20100CT Schottky 100V 20A Barrier rectifier?
These are reasonable price too.
R
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Author: Tim WescottDate: 13:21 16-10-07
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Roger Dewhurst wrote:
> "Tim Wescott" <tim@seemywebsite.com> wrote in message
> news:p7OdnTDQ1NJ1eI7anZ2dnUVZ_hSdnZ2d@web-ster.com...
>> Roger Dewhurst wrote:
>>> How are the pins of a mosfet identified please.
>>>
>>> The project requires a 45V/16A Schottky diode or similar. I cannot find
>>> a supplier. What is special about a Schottky diode? Can I use smaller
>>> diodes wired in parallel?
>>>
>> A MOSFET has a source, drain and gate. To identify the pins on a given
>> part you need to look at a data sheet. There's typically one common way
>> of connecting them (e.g. a TO-220 package almost always puts the drain on
>> the middle pin and the tab, for heat sinking), but it's not universal.
>
> Thanks. I have got the data sheet now.
>
>> Shottkey diodes are fast, and they tend to have a lower forward drop for
>> the current than regular silicon diodes. They're also more expensive and
>> hard to get in high reverse-voltage ratings, but you can't have
>> everything.
>>
>> 45V/16A is one honkin' big diode! You could parallel multiple lower
>> current diodes if you wired a small resistor in series with each one to
>> insure current balancing, but you may run into other problems doing that.
>> Perhaps you could post the part number of the required diode and someone
>> here could help you find it.
>
> Can I use one half of a MBR20100CT Schottky 100V 20A Barrier rectifier?
> These are reasonable price too.
>
> R
>
>
"20 amp total (10 per diode leg)". Look at the marketing fluff to feel
good, look at the data sheet to see if the part will work.
Given that the diodes are well matched thermally, you may be able to
connect them in parallel, but I'd want to experiment with it a bit
before I really trusted it. You should also check to see if you need
heat sinking.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
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Author: Roger DewhurstDate: 15:35 16-10-07
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"Tim Wescott" <tim@seemywebsite.com> wrote in message
news:75OdnW1r1M_Nb4nanZ2dnUVZ_oCvnZ2d@web-ster.com...
> Roger Dewhurst wrote:
>> "Tim Wescott" <tim@seemywebsite.com> wrote in message
>> news:p7OdnTDQ1NJ1eI7anZ2dnUVZ_hSdnZ2d@web-ster.com...
>>> Roger Dewhurst wrote:
>>>> How are the pins of a mosfet identified please.
>>>>
>>>> The project requires a 45V/16A Schottky diode or similar. I cannot
>>>> find a supplier. What is special about a Schottky diode? Can I use
>>>> smaller diodes wired in parallel?
>>>>
>>> A MOSFET has a source, drain and gate. To identify the pins on a given
>>> part you need to look at a data sheet. There's typically one common way
>>> of connecting them (e.g. a TO-220 package almost always puts the drain
>>> on the middle pin and the tab, for heat sinking), but it's not
>>> universal.
>>
>> Thanks. I have got the data sheet now.
>>
>>> Shottkey diodes are fast, and they tend to have a lower forward drop for
>>> the current than regular silicon diodes. They're also more expensive
>>> and hard to get in high reverse-voltage ratings, but you can't have
>>> everything.
>>>
>>> 45V/16A is one honkin' big diode! You could parallel multiple lower
>>> current diodes if you wired a small resistor in series with each one to
>>> insure current balancing, but you may run into other problems doing
>>> that. Perhaps you could post the part number of the required diode and
>>> someone here could help you find it.
>>
>> Can I use one half of a MBR20100CT Schottky 100V 20A Barrier rectifier?
>> These are reasonable price too.
>>
>> R
> "20 amp total (10 per diode leg)". Look at the marketing fluff to feel
> good, look at the data sheet to see if the part will work.
>
> Given that the diodes are well matched thermally, you may be able to
> connect them in parallel, but I'd want to experiment with it a bit before
> I really trusted it. You should also check to see if you need heat
> sinking.
Thanks. I wonder why I did not think of running them in parallel. The data
sheet shows it as two diodes sharing a cathode on pin 2 with nothing else in
the package.
R
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