OP amp
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Posts: 46,084
Need recommendation for basic OP Amp with rail to rail of 0-5 v for input
to ADC.
Something fast and easy ( Radio Scrap part # ) would be good.
Original Message
From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=utKJHESfF2Q1sHokE6Qp4Zoq6g5ubFB4zi7yCo4wPum-GOC8lc2MWvt01qWecNyqd1UX2EfS1Ppy]alw@a...[/url
Sent: Thursday, February 20, 2003 11:34 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Electrolytic vs Tantalum
You might enjoy http://www.wd5gnr.com/caps.htm
Tantalum capacitors have many excellent qualities, but in this case you
are probably seeing them replace an electrolytic to reduce size. There
are other factors such as ESR and leakage, but in this case, that
probably isn't a factor.
Tantalum capacitors have higher failure rates at high temperature than
low temperature, and also their MTBF decreases as you run closer to
their rated voltage.
Read this:
http://www.illcap.com/pdf/papers/A_Comparison_Of_Surface_Mount_Aluminum.
pdf
From that paper:
Among the advantages [noparse][[/noparse]of tantalum] are:
! Small size
! No liquid electrolyte
! Superior temperature stability
! Wider operating temperature range (up to +125°C)
! Long storage (shelf) life
! Larger reverse voltage tolerance
! Low dissipation factor
! Self healing
Aluminum electrolytic capacitors do have several advantages over
tantalum capacitors.
Most prominently:
! Lower cost
! Higher availability
! Shorter production lead times
! Low leakage current
! Higher voltage range (up to 400 VDC)
Some of the most prominent electrical performance differences between
tantalums and aluminum electrolytics
that should be resolved before substituting an aluminum electrolytic for
a tantalum capacitor are:
! Aluminum electrolytic's higher dissipation factors/ESR, which in turn
reduces their ripple current
capabilities.
! Aluminum electrolytic's larger capacitance change over temperature.
Electrolytics can change up to six
times more than tantalums.
! Aluminum electrolytic's capacitance change over frequency.
! Aluminum electrolytic's changes over time -- up 20% after 2,000 hours
for aluminum electrolytics.
### end quote
Years ago, electrolytic capacitors were largely regarded as junk parts.
But modern advances have made them much more robust, although they are
larger than a comparable tantalum.
One interesting note about electrolytic capacitors. Do you know why
electrolytic caps can reach such high values? Capacitance is determined
by the surface area of the plates and the spacing between the plates.
The closer the plates, the higher the capacitance. To maximize space
when using metal films (like in a metal film capacitor) you roll the
metal and the insulator like a tootsie roll, so that unrolled it would
be a big sheet of metal and plastic.
Electrolytics are different. The capacitors contain a conductive fluid
(as you know if you've hooked one up backwards). When you apply current,
the fluid "plates' a thin insulating layer on one electrode. That's why
the capacitor has a polarity. So one plate is the electrode, and the
other plate is the fluid. The dielectric is the extremely thin plated
layer that is thinner than you could reasonably build with mechanical
means. This very thin gap is where electrolytics get their high values.
Al Williams
AWC
* Floating point A/D
http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: smartdim@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=-qqQs4bcdRocT0Hep1QlA1f24-IXVlDlU7Zs3riXJ80PDEnFaZGGV3pkSyByWApw1IKaKanHU0UtbIc]smartdim@a...[/url
> Sent: Thursday, February 20, 2003 9:19 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Electrolytic vs Tantalum
>
>
> Looking for a decent explanation on filter caps.
> I completly understand the concept of the small .1 uf cap
> close to the power
> supply for decoupling (at least I think I do). Also I think I
> have a decent
> handle on why to use an electrolytic (much higher value) in
> tandem with the
> 0.1uf cap.
>
> However, it seems more and more I am seeing tantalum caps on
> the output next
> to the power supply to work in tandem with the 0.1uf ceramic.
>
> For example, in the case of the SX demo board from parallax,
> the cap on the
> input side of the 5v reg is electrolytic and the cap on the
> output of the 5v
> reg is tantalum. I am sure this probably has something to do with the
> characteistics of the different caps.
>
> Can anybody give a quikie "caps 101" explanation on when and
> why to use
> electrolytic verses tantalum?
>
> Thanks
>
> Dummy
>
>
> [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/
[noparse][[/noparse]Non-text portions of this message have been removed]
to ADC.
Something fast and easy ( Radio Scrap part # ) would be good.
Original Message
From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=utKJHESfF2Q1sHokE6Qp4Zoq6g5ubFB4zi7yCo4wPum-GOC8lc2MWvt01qWecNyqd1UX2EfS1Ppy]alw@a...[/url
Sent: Thursday, February 20, 2003 11:34 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Electrolytic vs Tantalum
You might enjoy http://www.wd5gnr.com/caps.htm
Tantalum capacitors have many excellent qualities, but in this case you
are probably seeing them replace an electrolytic to reduce size. There
are other factors such as ESR and leakage, but in this case, that
probably isn't a factor.
Tantalum capacitors have higher failure rates at high temperature than
low temperature, and also their MTBF decreases as you run closer to
their rated voltage.
Read this:
http://www.illcap.com/pdf/papers/A_Comparison_Of_Surface_Mount_Aluminum.
From that paper:
Among the advantages [noparse][[/noparse]of tantalum] are:
! Small size
! No liquid electrolyte
! Superior temperature stability
! Wider operating temperature range (up to +125°C)
! Long storage (shelf) life
! Larger reverse voltage tolerance
! Low dissipation factor
! Self healing
Aluminum electrolytic capacitors do have several advantages over
tantalum capacitors.
Most prominently:
! Lower cost
! Higher availability
! Shorter production lead times
! Low leakage current
! Higher voltage range (up to 400 VDC)
Some of the most prominent electrical performance differences between
tantalums and aluminum electrolytics
that should be resolved before substituting an aluminum electrolytic for
a tantalum capacitor are:
! Aluminum electrolytic's higher dissipation factors/ESR, which in turn
reduces their ripple current
capabilities.
! Aluminum electrolytic's larger capacitance change over temperature.
Electrolytics can change up to six
times more than tantalums.
! Aluminum electrolytic's capacitance change over frequency.
! Aluminum electrolytic's changes over time -- up 20% after 2,000 hours
for aluminum electrolytics.
### end quote
Years ago, electrolytic capacitors were largely regarded as junk parts.
But modern advances have made them much more robust, although they are
larger than a comparable tantalum.
One interesting note about electrolytic capacitors. Do you know why
electrolytic caps can reach such high values? Capacitance is determined
by the surface area of the plates and the spacing between the plates.
The closer the plates, the higher the capacitance. To maximize space
when using metal films (like in a metal film capacitor) you roll the
metal and the insulator like a tootsie roll, so that unrolled it would
be a big sheet of metal and plastic.
Electrolytics are different. The capacitors contain a conductive fluid
(as you know if you've hooked one up backwards). When you apply current,
the fluid "plates' a thin insulating layer on one electrode. That's why
the capacitor has a polarity. So one plate is the electrode, and the
other plate is the fluid. The dielectric is the extremely thin plated
layer that is thinner than you could reasonably build with mechanical
means. This very thin gap is where electrolytics get their high values.
Al Williams
AWC
* Floating point A/D
http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: smartdim@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=-qqQs4bcdRocT0Hep1QlA1f24-IXVlDlU7Zs3riXJ80PDEnFaZGGV3pkSyByWApw1IKaKanHU0UtbIc]smartdim@a...[/url
> Sent: Thursday, February 20, 2003 9:19 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Electrolytic vs Tantalum
>
>
> Looking for a decent explanation on filter caps.
> I completly understand the concept of the small .1 uf cap
> close to the power
> supply for decoupling (at least I think I do). Also I think I
> have a decent
> handle on why to use an electrolytic (much higher value) in
> tandem with the
> 0.1uf cap.
>
> However, it seems more and more I am seeing tantalum caps on
> the output next
> to the power supply to work in tandem with the 0.1uf ceramic.
>
> For example, in the case of the SX demo board from parallax,
> the cap on the
> input side of the 5v reg is electrolytic and the cap on the
> output of the 5v
> reg is tantalum. I am sure this probably has something to do with the
> characteistics of the different caps.
>
> Can anybody give a quikie "caps 101" explanation on when and
> why to use
> electrolytic verses tantalum?
>
> Thanks
>
> Dummy
>
>
> [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/
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
rail, .3 mv offset
At 04:09 PM 2/20/2003 -0500, you wrote:
>Need recommendation for basic OP Amp with rail to rail of 0-5 v for input
>to ADC.
>Something fast and easy ( Radio Scrap part # ) would be good.
Larry Bradley
Orleans (Ottawa), Ontario, CANADA