basic stamp voltage regulator
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Posts: 46,084
Hi mark,
If you use a REGULATED 5V source you MUST power the stamp via its VDD pin
(leave Vin disconnected !!).
The Vin pin is for voltages that are between 5.5V and 15V and these may have
some ripple as the stamp's internal regulator fixes this. If you use the Vin
pin then you must NOT connect
a 5V source to the VDD pin.
Greetings peter
Oorspronkelijk bericht
Van: markallen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=7t4tgO27tl2betmzJsdWrJtH5EnPaxhJGQFY_11Zb7jEgUjLh6KKQdAdashduICYlmhwVOWxK-EexiaTFQ]markallen@m...[/url
Verzonden: dinsdag 10 juli 2001 23:31
Aan: basicstamps@yahoogroups.com
Onderwerp: [noparse][[/noparse]basicstamps] basic stamp voltage regulator
If I'm powering the stamp with voltage that is being filtered through
a 5v regulator, should I hook it up to the vin pin, vdd pin, or does
it matter?
thanks!
Mark
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If you use a REGULATED 5V source you MUST power the stamp via its VDD pin
(leave Vin disconnected !!).
The Vin pin is for voltages that are between 5.5V and 15V and these may have
some ripple as the stamp's internal regulator fixes this. If you use the Vin
pin then you must NOT connect
a 5V source to the VDD pin.
Greetings peter
Oorspronkelijk bericht
Van: markallen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=7t4tgO27tl2betmzJsdWrJtH5EnPaxhJGQFY_11Zb7jEgUjLh6KKQdAdashduICYlmhwVOWxK-EexiaTFQ]markallen@m...[/url
Verzonden: dinsdag 10 juli 2001 23:31
Aan: basicstamps@yahoogroups.com
Onderwerp: [noparse][[/noparse]basicstamps] basic stamp voltage regulator
If I'm powering the stamp with voltage that is being filtered through
a 5v regulator, should I hook it up to the vin pin, vdd pin, or does
it matter?
thanks!
Mark
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Comments
a 5v regulator, should I hook it up to the vin pin, vdd pin, or does
it matter?
thanks!
Mark
The Vin pin on the Stamp goes to the same voltage that is fed to the input of
the regulator. I don't know that it is really necessary to hook up but it's
better not to take a chance.
Sid
>
>If you use a REGULATED 5V source you MUST power the stamp via its VDD pin
>(leave Vin disconnected !!).
>The Vin pin is for voltages that are between 5.5V and 15V and these may have
>some ripple as the stamp's internal regulator fixes this. If you use the Vin
>pin then you must NOT connect
>a 5V source to the VDD pin.
Peter, thanks for the advice. Out of curiosity, what is the problem
with hooking 5v up to Vin? Is it that 5v is just a little to small a
voltage? Or is it just redundant to regulate the voltage twice?
-Mark
You just gave the answer. The stamp regulator is a small current version
of a 7805-type regulator and therefore needs a higher voltage at its input.
All
this information is also described in the stamp's manual with more
specifics.
Greetings peter
Oorspronkelijk bericht
Van: markallen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ZwWMYxEvwugL3SFgogV2iPSbknY1jAdH1rGk1ewx9EdagZz6cvr3qPs4MFNW51cIe0jW3spheuLZMFjxJEqw]markallen@m...[/url
Verzonden: woensdag 11 juli 2001 02:13
Aan: basicstamps@yahoogroups.com
Onderwerp: RE: [noparse][[/noparse]basicstamps] basic stamp voltage regulator
>Hi mark,
>
>If you use a REGULATED 5V source you MUST power the stamp via its VDD pin
>(leave Vin disconnected !!).
>The Vin pin is for voltages that are between 5.5V and 15V and these may
have
>some ripple as the stamp's internal regulator fixes this. If you use the
Vin
>pin then you must NOT connect
>a 5V source to the VDD pin.
Peter, thanks for the advice. Out of curiosity, what is the problem
with hooking 5v up to Vin? Is it that 5v is just a little to small a
voltage? Or is it just redundant to regulate the voltage twice?
-Mark
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does not have to have 3 or 4 volts higher than the regulator rating to get
proper regulation. The Stamp manual says Vin should be 5.5 to 12 volts DC,
with 7.5 volts DC being optimal. Vin should be left unconnected if a
regulated 5 volts is supplied to Vdd from an external source.
Original Message
> You just gave the answer. The stamp regulator is a small current version
> of a 7805-type regulator and therefore needs a higher voltage at its
input.
> All
> this information is also described in the stamp's manual with more
> specifics.
> >If you use a REGULATED 5V source you MUST power the stamp via its VDD pin
> >(leave Vin disconnected !!).
> >The Vin pin is for voltages that are between 5.5V and 15V and these may
> have
> >some ripple as the stamp's internal regulator fixes this. If you use the
> Vin
> >pin then you must NOT connect
> >a 5V source to the VDD pin.
>
>
> Peter, thanks for the advice. Out of curiosity, what is the problem
> with hooking 5v up to Vin? Is it that 5v is just a little to small a
> voltage? Or is it just redundant to regulate the voltage twice?
VIN will regulate the voltage DOWN from 5.5 to 12
volts (15 for the Stamp I), so starting too low will
not yield enough voltage. There is the advantage when
using external power regulation (that is, a +5 volt
power supply) in that each group of eight pins (0..7,
8..15) can source or sink 100 mA - effectively 3, 30
mA pins, while with internal regulation using VIN, the
limit is 75 mA for ALL pins. So you would not want to
use VIN if you have a regulated 5 volt supply. On the
other hand, if you do not have a 5 volt supply and so
use VIN, VDD then outputs 5 volts that could be used
as the reference for shift registers or ADC's.
By the way, with regard to the current limits on
groups of eight pins, my current application may have
a flaw. One group of eight pins has _CS, CLK, and DIO
for use with ADC's, plus two LED's, both of which may
be on simultaneously. Perhaps someone can help me
understand whether this is a problem when, for
instance, sending SHIFTOUT configuration over DIO to
the LTC1298 ADC with both LED's High (at which point
CLK would be pulsing but _CS would be Low). Would this
be a problem area (4 * 30 mA > 100 mA), and if so
would it be the only problem area (in which case I can
modify my light sequence so that only one of the two
lights is on at once)? Or do I have a problem when
only one LED is High, SHIFTOUT is using CLK and DIO,
and both _CS and the second LED are set Low?
Regards,
Bob Pence
--- markallen <markallen@m...> wrote:
> >Hi mark,
> >
> >If you use a REGULATED 5V source you MUST power the
> stamp via its VDD pin
> >(leave Vin disconnected !!).
> >The Vin pin is for voltages that are between 5.5V
> and 15V and these may have
> >some ripple as the stamp's internal regulator fixes
> this. If you use the Vin
> >pin then you must NOT connect
> >a 5V source to the VDD pin.
>
>
> Peter, thanks for the advice. Out of curiosity, what
> is the problem
> with hooking 5v up to Vin? Is it that 5v is just a
> little to small a
> voltage? Or is it just redundant to regulate the
> voltage twice?
>
> -Mark
>
>
> To UNSUBSCRIBE, just send mail to:
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> 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/
>
>
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