Two quick questions - ADC inputs and overheating
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Posts: 46,084
--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
wrote:
> Where should the resistor go?
>
Often one puts a resistor between the circuit being senced and the
ADC input. that way, the current is limited to some small value.
you would need to check to make sure the current was high enough that
it could drive the ADC input.
And you would need to make sure it was included in any calcs for
voltage drop thru the ADC. In some cases, the ADC acts like a
voltage divider so adding another resistor might change the expected
output requiring a little software offset.
Dave
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Tuesday, April 29, 2003 9:15 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
>
> did you put in a 10K resistor to limit the current ?
>
> are you measuring direct or thru a voltage divider ?
>
> Dave
>
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > The adc was hot, I have a board of education so the board and
stamp
> were
> > being run by a 9v battery, and the adc was connected to the
battery
> that
> > my robot is going to use.
> >
> >
Original Message
> > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > Sent: Tuesday, April 29, 2003 8:35 PM
> > To: basicstamps@yahoogroups.com
> > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> >
> > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > laxboy687@e... writes:
> >
> > > Hi all,
> > >
> > > I just started to incorporate a voltage monitoring system into
my
> > > project using the adc8031, BS2, and a 4.8 v battery.
> > > I was running it and the voltage was coming up fine, but I
noticed
> > that
> > > it was extremely hot, I touched it and was almost blister hot.
> > > Is this standard?
> > > My other question was, I'm running out of I/O pins and I have
an
> lcd
> > > screen and I read some where that you can tri-state one of the
> data
> > bus
> > > lines.
> > > What does this mean and can I do it? I just want to add a sharp
> > Gpd02-4
> > > to my project, and just need one more pin.
> > >
> > > -Mike
> > >
> >
> > "blister hot" is not normal! Some part of your circuit is pulling
> too
> > much
> > current.
> >
> > Also, what was extreemly hot, the stamp, the adc???
> >
> > What input voltage are you running to power the stamp?
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > 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/
>
>
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wrote:
> Where should the resistor go?
>
Often one puts a resistor between the circuit being senced and the
ADC input. that way, the current is limited to some small value.
you would need to check to make sure the current was high enough that
it could drive the ADC input.
And you would need to make sure it was included in any calcs for
voltage drop thru the ADC. In some cases, the ADC acts like a
voltage divider so adding another resistor might change the expected
output requiring a little software offset.
Dave
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Tuesday, April 29, 2003 9:15 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
>
> did you put in a 10K resistor to limit the current ?
>
> are you measuring direct or thru a voltage divider ?
>
> Dave
>
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > The adc was hot, I have a board of education so the board and
stamp
> were
> > being run by a 9v battery, and the adc was connected to the
battery
> that
> > my robot is going to use.
> >
> >
Original Message
> > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > Sent: Tuesday, April 29, 2003 8:35 PM
> > To: basicstamps@yahoogroups.com
> > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> >
> > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > laxboy687@e... writes:
> >
> > > Hi all,
> > >
> > > I just started to incorporate a voltage monitoring system into
my
> > > project using the adc8031, BS2, and a 4.8 v battery.
> > > I was running it and the voltage was coming up fine, but I
noticed
> > that
> > > it was extremely hot, I touched it and was almost blister hot.
> > > Is this standard?
> > > My other question was, I'm running out of I/O pins and I have
an
> lcd
> > > screen and I read some where that you can tri-state one of the
> data
> > bus
> > > lines.
> > > What does this mean and can I do it? I just want to add a sharp
> > Gpd02-4
> > > to my project, and just need one more pin.
> > >
> > > -Mike
> > >
> >
> > "blister hot" is not normal! Some part of your circuit is pulling
> too
> > much
> > current.
> >
> > Also, what was extreemly hot, the stamp, the adc???
> >
> > What input voltage are you running to power the stamp?
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > 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/
>
>
> To UNSUBSCRIBE, just send mail to:
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Comments
only hooked up to my battery that it tests, it gets hot.
Original Message
From: Dave Mucha [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=pVnA2YViCl_Mf78RnpUCxdxzzTFQUjq8iEqxZ-TcdmJyIKftocbdlAs58YKIC7ZcLbVAe4SPag9-jnmTUg]davemucha@j...[/url
Sent: Wednesday, April 30, 2003 9:51 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
overheating
--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
wrote:
> Where should the resistor go?
>
Often one puts a resistor between the circuit being senced and the
ADC input. that way, the current is limited to some small value.
you would need to check to make sure the current was high enough that
it could drive the ADC input.
And you would need to make sure it was included in any calcs for
voltage drop thru the ADC. In some cases, the ADC acts like a
voltage divider so adding another resistor might change the expected
output requiring a little software offset.
Dave
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Tuesday, April 29, 2003 9:15 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
>
> did you put in a 10K resistor to limit the current ?
>
> are you measuring direct or thru a voltage divider ?
>
> Dave
>
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > The adc was hot, I have a board of education so the board and
stamp
> were
> > being run by a 9v battery, and the adc was connected to the
battery
> that
> > my robot is going to use.
> >
> >
Original Message
> > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > Sent: Tuesday, April 29, 2003 8:35 PM
> > To: basicstamps@yahoogroups.com
> > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> >
> > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > laxboy687@e... writes:
> >
> > > Hi all,
> > >
> > > I just started to incorporate a voltage monitoring system into
my
> > > project using the adc8031, BS2, and a 4.8 v battery.
> > > I was running it and the voltage was coming up fine, but I
noticed
> > that
> > > it was extremely hot, I touched it and was almost blister hot.
> > > Is this standard?
> > > My other question was, I'm running out of I/O pins and I have
an
> lcd
> > > screen and I read some where that you can tri-state one of the
> data
> > bus
> > > lines.
> > > What does this mean and can I do it? I just want to add a sharp
> > Gpd02-4
> > > to my project, and just need one more pin.
> > >
> > > -Mike
> > >
> >
> > "blister hot" is not normal! Some part of your circuit is pulling
> too
> > much
> > current.
> >
> > Also, what was extreemly hot, the stamp, the adc???
> >
> > What input voltage are you running to power the stamp?
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> > 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/
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
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> and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
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To UNSUBSCRIBE, just send mail to:
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Check your wiring to the ADC if it is not too late.
>Here's one more bit of information that I forgot. Even when the adc is
>only hooked up to my battery that it tests, it gets hot.
>
>
Original Message
>From: Dave Mucha [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=FVDzqJywENE-o7v9-OTLLb0tGIzBBbv8OAnIYDJyFa3_OpFH3j5Zw4TaELeqbTc7LaC7inKzvGCQUg]davemucha@j...[/url
>Sent: Wednesday, April 30, 2003 9:51 AM
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
>overheating
>
>--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
>wrote:
> > Where should the resistor go?
> >
>
>
>Often one puts a resistor between the circuit being senced and the
>ADC input. that way, the current is limited to some small value.
>
>you would need to check to make sure the current was high enough that
>it could drive the ADC input.
>
>And you would need to make sure it was included in any calcs for
>voltage drop thru the ADC. In some cases, the ADC acts like a
>voltage divider so adding another resistor might change the expected
>output requiring a little software offset.
>
>Dave
>
>
>
>
> >
Original Message
> > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > Sent: Tuesday, April 29, 2003 9:15 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
> >
> > did you put in a 10K resistor to limit the current ?
> >
> > are you measuring direct or thru a voltage divider ?
> >
> > Dave
> >
> >
> > --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> > wrote:
> > > The adc was hot, I have a board of education so the board and
>stamp
> > were
> > > being run by a 9v battery, and the adc was connected to the
>battery
> > that
> > > my robot is going to use.
> > >
> > >
Original Message
> > > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > > Sent: Tuesday, April 29, 2003 8:35 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> > >
> > > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > > laxboy687@e... writes:
> > >
> > > > Hi all,
> > > >
> > > > I just started to incorporate a voltage monitoring system into
>my
> > > > project using the adc8031, BS2, and a 4.8 v battery.
> > > > I was running it and the voltage was coming up fine, but I
>noticed
> > > that
> > > > it was extremely hot, I touched it and was almost blister hot.
> > > > Is this standard?
> > > > My other question was, I'm running out of I/O pins and I have
>an
> > lcd
> > > > screen and I read some where that you can tri-state one of the
> > data
> > > bus
> > > > lines.
> > > > What does this mean and can I do it? I just want to add a sharp
> > > Gpd02-4
> > > > to my project, and just need one more pin.
> > > >
> > > > -Mike
> > > >
> > >
> > > "blister hot" is not normal! Some part of your circuit is pulling
> > too
> > > much
> > > current.
> > >
> > > Also, what was extreemly hot, the stamp, the adc???
> > >
> > > What input voltage are you running to power the stamp?
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> > >
> > >
> > > 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/
> >
> >
> > 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/
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject
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>
>
>
>
>
>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.
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>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
wrote:
> There is nothing about an ADC that should perceivably get hot.
> Check your wiring to the ADC if it is not too late.
>
Too late is a good term. the ADC is a sensor only and should carry
NO power.
better verify each connection. if it is a double input and you are
using one with reference, the other is either open or tied to a
ground. make sure it is wired exactly per the data sheet for that
particular model.
also, check your serial connection wring both signal and grounds to
make sure it is not off chip.
if you isolate it to the chip itself, look for a replacement.
If you are really unsure, think about posting your circuit so one of
us can double check it for you.
Dave
> >Here's one more bit of information that I forgot. Even when the
adc is
> >only hooked up to my battery that it tests, it gets hot.
> >
> >
Original Message
> >From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> >Sent: Wednesday, April 30, 2003 9:51 AM
> >To: basicstamps@yahoogroups.com
> >Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> >overheating
> >
> >--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> >wrote:
> > > Where should the resistor go?
> > >
> >
> >
> >Often one puts a resistor between the circuit being senced and the
> >ADC input. that way, the current is limited to some small value.
> >
> >you would need to check to make sure the current was high enough
that
> >it could drive the ADC input.
> >
> >And you would need to make sure it was included in any calcs for
> >voltage drop thru the ADC. In some cases, the ADC acts like a
> >voltage divider so adding another resistor might change the
expected
> >output requiring a little software offset.
> >
> >Dave
> >
> >
> >
> >
> > >
Original Message
> > > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > > Sent: Tuesday, April 29, 2003 9:15 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
> > >
> > > did you put in a 10K resistor to limit the current ?
> > >
> > > are you measuring direct or thru a voltage divider ?
> > >
> > > Dave
> > >
> > >
> > > --- In basicstamps@yahoogroups.com, "Mike Dillon"
<laxboy687@e...>
> > > wrote:
> > > > The adc was hot, I have a board of education so the board and
> >stamp
> > > were
> > > > being run by a 9v battery, and the adc was connected to the
> >battery
> > > that
> > > > my robot is going to use.
> > > >
> > > >
Original Message
> > > > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > > > Sent: Tuesday, April 29, 2003 8:35 PM
> > > > To: basicstamps@yahoogroups.com
> > > > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> > > >
> > > > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > > > laxboy687@e... writes:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I just started to incorporate a voltage monitoring system
into
> >my
> > > > > project using the adc8031, BS2, and a 4.8 v battery.
> > > > > I was running it and the voltage was coming up fine, but I
> >noticed
> > > > that
> > > > > it was extremely hot, I touched it and was almost blister
hot.
> > > > > Is this standard?
> > > > > My other question was, I'm running out of I/O pins and I
have
> >an
> > > lcd
> > > > > screen and I read some where that you can tri-state one of
the
> > > data
> > > > bus
> > > > > lines.
> > > > > What does this mean and can I do it? I just want to add a
sharp
> > > > Gpd02-4
> > > > > to my project, and just need one more pin.
> > > > >
> > > > > -Mike
> > > > >
> > > >
> > > > "blister hot" is not normal! Some part of your circuit is
pulling
> > > too
> > > > much
> > > > current.
> > > >
> > > > Also, what was extreemly hot, the stamp, the adc???
> > > >
> > > > What input voltage are you running to power the stamp?
> > > >
> > > >
> > > > [noparse][[/noparse]Non-text portions of this message have been removed]
> > > >
> > > >
> > > > 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/
> > >
> > >
> > > 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/
> >
> >
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Subject
> >and Body of the message will be ignored.
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> >
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> >
> >
> >
> >
> >
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> >Your use of Yahoo! Groups is subject to
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The ADC0831 is supposed to be POWERED by 4.5 to
6.3 volts, (with an internal zener to protect it,
see the data sheet National Semiconductor). If
you go above 6.3 volts, a series resistor is
recommended to limit the VCC current. May be
your problem.
It can then measure an analog signal between
0 and VCC volts (rail to rail).
( And, from the Docs: )
"Note 4: When the input voltage (VIN) at any pin
exceeds the power supply rails (VIN < V- or VIN >
V+) the absolute value of current at that pin
should be limited to 5 mA or less. The 20 mA
package input current limits the number of pins
that can exceed the power supply boundaries with a
5 mA current limit to four."
So if you want to measure more voltage than is
powering the chip, you MUST use a voltage divider
resistor network to drop the voltage at the pin,
the re-scale the results in software.
In general, when something gets hot that isn't
supposed to, there's current running somewhere
it shouldn't.
--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
wrote:
> Here's one more bit of information that I forgot. Even when the adc
is
> only hooked up to my battery that it tests, it gets hot.
>
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Wednesday, April 30, 2003 9:51 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> overheating
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > Where should the resistor go?
> >
>
>
> Often one puts a resistor between the circuit being senced and the
> ADC input. that way, the current is limited to some small value.
>
> you would need to check to make sure the current was high enough
that
> it could drive the ADC input.
>
> And you would need to make sure it was included in any calcs for
> voltage drop thru the ADC. In some cases, the ADC acts like a
> voltage divider so adding another resistor might change the
expected
> output requiring a little software offset.
>
> Dave
>
>
>
>
> >
Original Message
> > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > Sent: Tuesday, April 29, 2003 9:15 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
> >
> > did you put in a 10K resistor to limit the current ?
> >
> > are you measuring direct or thru a voltage divider ?
> >
> > Dave
> >
> >
> > --- In basicstamps@yahoogroups.com, "Mike Dillon"
<laxboy687@e...>
> > wrote:
> > > The adc was hot, I have a board of education so the board and
> stamp
> > were
> > > being run by a 9v battery, and the adc was connected to the
> battery
> > that
> > > my robot is going to use.
> > >
> > >
Original Message
> > > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > > Sent: Tuesday, April 29, 2003 8:35 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> > >
> > > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > > laxboy687@e... writes:
> > >
> > > > Hi all,
> > > >
> > > > I just started to incorporate a voltage monitoring system
into
> my
> > > > project using the adc8031, BS2, and a 4.8 v battery.
> > > > I was running it and the voltage was coming up fine, but I
> noticed
> > > that
> > > > it was extremely hot, I touched it and was almost blister hot.
> > > > Is this standard?
> > > > My other question was, I'm running out of I/O pins and I have
> an
> > lcd
> > > > screen and I read some where that you can tri-state one of
the
> > data
> > > bus
> > > > lines.
> > > > What does this mean and can I do it? I just want to add a
sharp
> > > Gpd02-4
> > > > to my project, and just need one more pin.
> > > >
> > > > -Mike
> > > >
> > >
> > > "blister hot" is not normal! Some part of your circuit is
pulling
> > too
> > > much
> > > current.
> > >
> > > Also, what was extreemly hot, the stamp, the adc???
> > >
> > > What input voltage are you running to power the stamp?
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
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> > Subject
> > > and Body of the message will be ignored.
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correct?
The chip is measuring a 4.8v battery. I think that is within the specs
that
Allan stated.
Heres my schematic with it getting hot.
_______
P1 on BS2 ---|1 8|----VCC on BS2
(4.8V+ bat )---|2 7|---- P3 on BS2
(4.8V- bat )---|3 6|---- P2 on BS2
VSS ---|4 5|----VCC on BS2
Original Message
From: Allan Lane [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=fT08uDb2zCyNpZXtCvldESnvPrthESOzMsesOOtaqDuBokeY0bqsp33AGn-TEhYZe-PtUKQPU86UCDNvgthzGHcQRg]allan.lane@h...[/url
Sent: Wednesday, April 30, 2003 4:55 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
overheating
Hey, it just occurred to me:
The ADC0831 is supposed to be POWERED by 4.5 to
6.3 volts, (with an internal zener to protect it,
see the data sheet National Semiconductor). If
you go above 6.3 volts, a series resistor is
recommended to limit the VCC current. May be
your problem.
It can then measure an analog signal between
0 and VCC volts (rail to rail).
( And, from the Docs: )
"Note 4: When the input voltage (VIN) at any pin
exceeds the power supply rails (VIN < V- or VIN >
V+) the absolute value of current at that pin
should be limited to 5 mA or less. The 20 mA
package input current limits the number of pins
that can exceed the power supply boundaries with a
5 mA current limit to four."
So if you want to measure more voltage than is
powering the chip, you MUST use a voltage divider
resistor network to drop the voltage at the pin,
the re-scale the results in software.
In general, when something gets hot that isn't
supposed to, there's current running somewhere
it shouldn't.
--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
wrote:
> Here's one more bit of information that I forgot. Even when the adc
is
> only hooked up to my battery that it tests, it gets hot.
>
>
Original Message
> From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> Sent: Wednesday, April 30, 2003 9:51 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> overheating
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > Where should the resistor go?
> >
>
>
> Often one puts a resistor between the circuit being senced and the
> ADC input. that way, the current is limited to some small value.
>
> you would need to check to make sure the current was high enough
that
> it could drive the ADC input.
>
> And you would need to make sure it was included in any calcs for
> voltage drop thru the ADC. In some cases, the ADC acts like a
> voltage divider so adding another resistor might change the
expected
> output requiring a little software offset.
>
> Dave
>
>
>
>
> >
Original Message
> > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > Sent: Tuesday, April 29, 2003 9:15 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions
> >
> > did you put in a 10K resistor to limit the current ?
> >
> > are you measuring direct or thru a voltage divider ?
> >
> > Dave
> >
> >
> > --- In basicstamps@yahoogroups.com, "Mike Dillon"
<laxboy687@e...>
> > wrote:
> > > The adc was hot, I have a board of education so the board and
> stamp
> > were
> > > being run by a 9v battery, and the adc was connected to the
> battery
> > that
> > > my robot is going to use.
> > >
> > >
Original Message
> > > From: smartdim@a... [noparse][[/noparse]mailto:smartdim@a...]
> > > Sent: Tuesday, April 29, 2003 8:35 PM
> > > To: basicstamps@yahoogroups.com
> > > Subject: Re: [noparse][[/noparse]basicstamps] Two quick questions
> > >
> > > In a message dated 4/29/2003 5:07:54 PM Pacific Daylight Time,
> > > laxboy687@e... writes:
> > >
> > > > Hi all,
> > > >
> > > > I just started to incorporate a voltage monitoring system
into
> my
> > > > project using the adc8031, BS2, and a 4.8 v battery.
> > > > I was running it and the voltage was coming up fine, but I
> noticed
> > > that
> > > > it was extremely hot, I touched it and was almost blister hot.
> > > > Is this standard?
> > > > My other question was, I'm running out of I/O pins and I have
> an
> > lcd
> > > > screen and I read some where that you can tri-state one of
the
> > data
> > > bus
> > > > lines.
> > > > What does this mean and can I do it? I just want to add a
sharp
> > > Gpd02-4
> > > > to my project, and just need one more pin.
> > > >
> > > > -Mike
> > > >
> > >
> > > "blister hot" is not normal! Some part of your circuit is
pulling
> > too
> > > much
> > > current.
> > >
> > > Also, what was extreemly hot, the stamp, the adc???
> > >
> > > What input voltage are you running to power the stamp?
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> > >
> > >
> > > 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/
> >
> >
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> > 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/
>
>
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Subject
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together (-Vin is tied to GND). Pins 5 and 8 are
also tied together (VCC is also your Vref --
which you have already done)
Your input (4.8V to zero) is tied to pin2, and
gives results compared to VRef.
It looks like you have a 'floating ground' problem,
currently -- which tieing -Vin to GND should fix.
Make sure you're using 'VDD' for +5 volts, NOT
'Vin' which is sitting around 9 to 12 volts on
the BOE. Your other BS2 data connections are
correct.
--- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
wrote:
> Ok so the chip is being powered by the VCC on my BOE, which is 5v
> correct?
> The chip is measuring a 4.8v battery. I think that is within the
specs
> that
> Allan stated.
>
> Heres my schematic with it getting hot.
> _______
> P1 on BS2 ---|1 8|----VCC on BS2
> (4.8V+ bat )---|2 7|---- P3 on BS2
> (4.8V- bat )---|3 6|---- P2 on BS2
> VSS ---|4 5|----VCC on BS2
>
>
>
Original Message
> From: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
> Sent: Wednesday, April 30, 2003 4:55 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> overheating
>
> Hey, it just occurred to me:
> The ADC0831 is supposed to be POWERED by 4.5 to
> 6.3 volts, (with an internal zener to protect it,
> see the data sheet National Semiconductor). If
> you go above 6.3 volts, a series resistor is
> recommended to limit the VCC current. May be
> your problem.
>
> It can then measure an analog signal between
> 0 and VCC volts (rail to rail).
> ( And, from the Docs: )
> "Note 4: When the input voltage (VIN) at any pin
> exceeds the power supply rails (VIN < V- or VIN >
> V+) the absolute value of current at that pin
> should be limited to 5 mA or less. The 20 mA
> package input current limits the number of pins
> that can exceed the power supply boundaries with a
> 5 mA current limit to four."
>
> So if you want to measure more voltage than is
> powering the chip, you MUST use a voltage divider
> resistor network to drop the voltage at the pin,
> the re-scale the results in software.
>
> In general, when something gets hot that isn't
> supposed to, there's current running somewhere
> it shouldn't.
>
plugged in upside down.
--- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...>
wrote:
> In the 'standard' approach, Pins 3 and 4 are tied
> together (-Vin is tied to GND). Pins 5 and 8 are
> also tied together (VCC is also your Vref --
> which you have already done)
>
> Your input (4.8V to zero) is tied to pin2, and
> gives results compared to VRef.
>
> It looks like you have a 'floating ground' problem,
> currently -- which tieing -Vin to GND should fix.
>
> Make sure you're using 'VDD' for +5 volts, NOT
> 'Vin' which is sitting around 9 to 12 volts on
> the BOE. Your other BS2 data connections are
> correct.
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > Ok so the chip is being powered by the VCC on my BOE, which is 5v
> > correct?
> > The chip is measuring a 4.8v battery. I think that is within the
> specs
> > that
> > Allan stated.
> >
> > Heres my schematic with it getting hot.
> > _______
> > P1 on BS2 ---|1 8|----VCC on BS2
> > (4.8V+ bat )---|2 7|---- P3 on BS2
> > (4.8V- bat )---|3 6|---- P2 on BS2
> > VSS ---|4 5|----VCC on BS2
> >
> >
> >
Original Message
> > From: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
> > Sent: Wednesday, April 30, 2003 4:55 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> > overheating
> >
> > Hey, it just occurred to me:
> > The ADC0831 is supposed to be POWERED by 4.5 to
> > 6.3 volts, (with an internal zener to protect it,
> > see the data sheet National Semiconductor). If
> > you go above 6.3 volts, a series resistor is
> > recommended to limit the VCC current. May be
> > your problem.
> >
> > It can then measure an analog signal between
> > 0 and VCC volts (rail to rail).
> > ( And, from the Docs: )
> > "Note 4: When the input voltage (VIN) at any pin
> > exceeds the power supply rails (VIN < V- or VIN >
> > V+) the absolute value of current at that pin
> > should be limited to 5 mA or less. The 20 mA
> > package input current limits the number of pins
> > that can exceed the power supply boundaries with a
> > 5 mA current limit to four."
> >
> > So if you want to measure more voltage than is
> > powering the chip, you MUST use a voltage divider
> > resistor network to drop the voltage at the pin,
> > the re-scale the results in software.
> >
> > In general, when something gets hot that isn't
> > supposed to, there's current running somewhere
> > it shouldn't.
> >
fine now!
-Mike
Original Message
From: Allan Lane [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=WkXWe3HgZ-HWJ-9YaMPsZ47PsoeMeyuGy2PjO47Vni0XvWLEbNACUgMWoZGh0uNGmlOlkw7UOFT5K7X3slkZLP7W]allan.lane@h...[/url
Sent: Thursday, May 01, 2003 11:48 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
overheating
Also, the ADC0831 chip could have been
plugged in upside down.
--- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...>
wrote:
> In the 'standard' approach, Pins 3 and 4 are tied
> together (-Vin is tied to GND). Pins 5 and 8 are
> also tied together (VCC is also your Vref --
> which you have already done)
>
> Your input (4.8V to zero) is tied to pin2, and
> gives results compared to VRef.
>
> It looks like you have a 'floating ground' problem,
> currently -- which tieing -Vin to GND should fix.
>
> Make sure you're using 'VDD' for +5 volts, NOT
> 'Vin' which is sitting around 9 to 12 volts on
> the BOE. Your other BS2 data connections are
> correct.
>
> --- In basicstamps@yahoogroups.com, "Mike Dillon" <laxboy687@e...>
> wrote:
> > Ok so the chip is being powered by the VCC on my BOE, which is 5v
> > correct?
> > The chip is measuring a 4.8v battery. I think that is within the
> specs
> > that
> > Allan stated.
> >
> > Heres my schematic with it getting hot.
> > _______
> > P1 on BS2 ---|1 8|----VCC on BS2
> > (4.8V+ bat )---|2 7|---- P3 on BS2
> > (4.8V- bat )---|3 6|---- P2 on BS2
> > VSS ---|4 5|----VCC on BS2
> >
> >
> >
Original Message
> > From: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
> > Sent: Wednesday, April 30, 2003 4:55 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: Two quick questions - ADC inputs and
> > overheating
> >
> > Hey, it just occurred to me:
> > The ADC0831 is supposed to be POWERED by 4.5 to
> > 6.3 volts, (with an internal zener to protect it,
> > see the data sheet National Semiconductor). If
> > you go above 6.3 volts, a series resistor is
> > recommended to limit the VCC current. May be
> > your problem.
> >
> > It can then measure an analog signal between
> > 0 and VCC volts (rail to rail).
> > ( And, from the Docs: )
> > "Note 4: When the input voltage (VIN) at any pin
> > exceeds the power supply rails (VIN < V- or VIN >
> > V+) the absolute value of current at that pin
> > should be limited to 5 mA or less. The 20 mA
> > package input current limits the number of pins
> > that can exceed the power supply boundaries with a
> > 5 mA current limit to four."
> >
> > So if you want to measure more voltage than is
> > powering the chip, you MUST use a voltage divider
> > resistor network to drop the voltage at the pin,
> > the re-scale the results in software.
> >
> > In general, when something gets hot that isn't
> > supposed to, there's current running somewhere
> > it shouldn't.
> >
To UNSUBSCRIBE, just send mail to:
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