Using MOSFETs with Basic stamps & BS2 outputs.
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Hey
Im new to microcontrollers and was wondering if anyone could help me
out I needed a few things clarified about their low current output
capabilities.
Firstly with regards to mosfets how much gate current do they
actually consume. I really don't understand how much current is
consumed by the gate and is there any way of working it out.
Furthermore I wanted to connect all of the BS2 pins to high current
devices and run them simultaneously what sort of approach should I
look at? Mosfets or Transistors.
Secondly with regards to transistors I was wondering if anyone could
help me select a sutiable transtor (incl base resistor...) that
draws less than 5ma Base current and allows me to control a load
that requires about 100-200 ma.
Also I have one last issue that needs to be resolved. The BS2p24 can
source a max of 60ma and sink a max of 60ma per 8 pins. Does this
mean if I source 120ma and sink 120ma (for a bank of 8 pins )that
there is an overall cancelling effect?
Any help you guys could give me would be greatly appreciated.
Many thanks
Arridh
Im new to microcontrollers and was wondering if anyone could help me
out I needed a few things clarified about their low current output
capabilities.
Firstly with regards to mosfets how much gate current do they
actually consume. I really don't understand how much current is
consumed by the gate and is there any way of working it out.
Furthermore I wanted to connect all of the BS2 pins to high current
devices and run them simultaneously what sort of approach should I
look at? Mosfets or Transistors.
Secondly with regards to transistors I was wondering if anyone could
help me select a sutiable transtor (incl base resistor...) that
draws less than 5ma Base current and allows me to control a load
that requires about 100-200 ma.
Also I have one last issue that needs to be resolved. The BS2p24 can
source a max of 60ma and sink a max of 60ma per 8 pins. Does this
mean if I source 120ma and sink 120ma (for a bank of 8 pins )that
there is an overall cancelling effect?
Any help you guys could give me would be greatly appreciated.
Many thanks
Arridh
Comments
(in theory, no current, but in practice there is always some leakage). It
may be overkill for you, but I like the IRL520 (see
http://www.al-williams.com/components.htm). These are simple to use and can
handle up to 9A with a 5V input.
I'd hook a large (100K) resistor from gate to ground. This provides a path
for current to flow and would consume about 5/100000 A plus the very small
gate current. The source goes to ground and the drain goes to what you want
to control.
This is way over kill for 200mA, but it will work and is inexpensive and
fairly foolproof.
The 60mA per 8 pin does not cancel out! The issue here is the size of the
transistor that feeds the port. This controls the maximum current per pin.
However, there are other transistors and components that feed the entire
bank of 8. If you exceed their limits, you will damage the chip. There is no
vector addition of current!
Al Williams
AWC
*Kits! http://www.al-williams.com/kits.htm
> Secondly with regards to transistors I was wondering if anyone could
> help me select a sutiable transtor (incl base resistor...) that
> draws less than 5ma Base current and allows me to control a load
> that requires about 100-200 ma.
>
> Also I have one last issue that needs to be resolved. The BS2p24 can
> source a max of 60ma and sink a max of 60ma per 8 pins. Does this
> mean if I source 120ma and sink 120ma (for a bank of 8 pins )that
> there is an overall cancelling effect?
>
> Any help you guys could give me would be greatly appreciated.
>
> Many thanks
> Arridh
>
>
>
> To UNSUBSCRIBE, just send mail to:
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>
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>
>
>
>
Rick
Original Message
From: "Al Williams" <alw@a...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, December 07, 2003 3:31 PM
Subject: RE: [noparse][[/noparse]basicstamps] Using MOSFETs with Basic stamps & BS2 outputs.
> MOSFETs are voltage operated and consume extremely small amounts of
current
> (in theory, no current, but in practice there is always some leakage). It
> may be overkill for you, but I like the IRL520 (see
> http://www.al-williams.com/components.htm). These are simple to use and
can
> handle up to 9A with a 5V input.
>
> I'd hook a large (100K) resistor from gate to ground. This provides a path
> for current to flow and would consume about 5/100000 A plus the very small
> gate current. The source goes to ground and the drain goes to what you
want
> to control.
>
> This is way over kill for 200mA, but it will work and is inexpensive and
> fairly foolproof.
>
> The 60mA per 8 pin does not cancel out! The issue here is the size of the
> transistor that feeds the port. This controls the maximum current per pin.
> However, there are other transistors and components that feed the entire
> bank of 8. If you exceed their limits, you will damage the chip. There is
no
> vector addition of current!
>
> Al Williams
> AWC
> *Kits! http://www.al-williams.com/kits.htm
>
>
> > Secondly with regards to transistors I was wondering if anyone could
> > help me select a sutiable transtor (incl base resistor...) that
> > draws less than 5ma Base current and allows me to control a load
> > that requires about 100-200 ma.
> >
> > Also I have one last issue that needs to be resolved. The BS2p24 can
> > source a max of 60ma and sink a max of 60ma per 8 pins. Does this
> > mean if I source 120ma and sink 120ma (for a bank of 8 pins )that
> > there is an overall cancelling effect?
> >
> > Any help you guys could give me would be greatly appreciated.
> >
> > Many thanks
> > Arridh
> >
> >
When you say "I like the IRL520" you should say "I sale the IRL520"
wrote:
> To Al Williams:
> When you say "I like the IRL520" you should say "I sale the IRL520"
My experience with Al Williams is that he only sells itmes that he
feels are of value. The mere fact that he might actually make 50
cents if he is lucky is rather picky.
People like Al serve the hobby well.
Peter H Anderson, http://www.phanderson.com, pha@p...
i can go to learn more about how to apply mosfets to
microcontrollers.
thnx for the info below too btw and how much current do you suppose
would be sourced with the 100K resistor for the mosfet? and also the
resistor is placed from the gate to ground somehwat like a pull down
right?
Arridh
--- In basicstamps@yahoogroups.com, "Al Williams" <alw@a...> wrote:
> MOSFETs are voltage operated and consume extremely small amounts
of current
> (in theory, no current, but in practice there is always some
leakage). It
> may be overkill for you, but I like the IRL520 (see
> http://www.al-williams.com/components.htm). These are simple to
use and can
> handle up to 9A with a 5V input.
>
> I'd hook a large (100K) resistor from gate to ground. This
provides a path
> for current to flow and would consume about 5/100000 A plus the
very small
> gate current. The source goes to ground and the drain goes to what
you want
> to control.
>
> This is way over kill for 200mA, but it will work and is
inexpensive and
> fairly foolproof.
>
> The 60mA per 8 pin does not cancel out! The issue here is the size
of the
> transistor that feeds the port. This controls the maximum current
per pin.
> However, there are other transistors and components that feed the
entire
> bank of 8. If you exceed their limits, you will damage the chip.
There is no
> vector addition of current!
>
> Al Williams
> AWC
> *Kits! http://www.al-williams.com/kits.htm
>
>
> > Secondly with regards to transistors I was wondering if anyone
could
> > help me select a sutiable transtor (incl base resistor...) that
> > draws less than 5ma Base current and allows me to control a load
> > that requires about 100-200 ma.
> >
> > Also I have one last issue that needs to be resolved. The BS2p24
can
> > source a max of 60ma and sink a max of 60ma per 8 pins. Does
this
> > mean if I source 120ma and sink 120ma (for a bank of 8 pins )
that
> > there is an overall cancelling effect?
> >
> > Any help you guys could give me would be greatly appreciated.
> >
> > Many thanks
> > Arridh
> >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
getting rich off a $1.50 part. But the point you seem to be missing is HE'S
NOT TELLING ANYONE TO BUY IT FROM HIM!! Buy it wherever you like, it's your
choice. In fact, if it wasn't for your post I never would have known he
carries them!
>Date: Mon, 08 Dec 2003 03:09:18 -0000
> From: "Albert Catano" <acatano2002@y...>
>Subject: RE: Using MOSFETs with Basic stamps & BS2 outputs.
>
>To Al Williams:
>When you say "I like the IRL520" you should say "I sale the IRL520"
_________________________________________________________________
Tired of slow downloads and busy signals? Get a high-speed Internet
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components unless they are something we use.
As Peter and Tom point out, I won't retire on MOSFETs any time soon!
Al Williams
AWC
* Kits: http://www.al-williams.com/kits.htm
>
Original Message
> From: Albert Catano [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=DBC8ssbFa0P07S-jqd6E_EmYL5K3NyNGigv5jY2t3toLCR2-nuxduFQwK8uUPllulXGLKzdwyFDYOC-neJAwlQ]acatano2002@y...[/url
> Sent: Sunday, December 07, 2003 9:09 PM
> To: basicstamps@yahoogroups.com
> Subject: RE: [noparse][[/noparse]basicstamps] Using MOSFETs with Basic stamps &
> BS2 outputs.
>
>
> To Al Williams:
> When you say "I like the IRL520" you should say "I sale the IRL520"
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
third paragraph says:
"This list is brought to you by Parallax, Inc. While OCASIONAL
discussion of other products are acceptable, postings intended to
advertise other products are unwelcome."
The Caps notation is mine.
This is supposed to be a HOBBY group, lets keep separated the hobby
stuff from the advertisement.