P
Phil Hobbs
Guest
On 2020-07-24 14:16, John Larkin wrote:
Sure, if it sits still. I\'d expect it to walk around a bit, what with
being a power op amp and all. (Widlar put a paper in the ISSC one
year that purported to prove that monolithic voltage regulators with
on-chip pass transistors were impossible due to thermal feedback.
Everybody believed it because it was Widlar. Then he came out with the
LM109/309.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
On Thu, 23 Jul 2020 21:29:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-07-23 20:28, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 02.14.39 UTC+2 skrev bitrex:
On 7/23/2020 7:47 PM, Lasse Langwadt Christensen wrote:
fredag den 24. juli 2020 kl. 01.12.21 UTC+2 skrev bitrex:
On 7/23/2020 7:01 PM, Lasse Langwadt Christensen wrote:
torsdag den 23. juli 2020 kl. 20.15.24 UTC+2 skrev Phil Hobbs:
ON still lists the TCA0372 power op amp as active, but total distributor
stock is less than 1k pieces and the quoted lead time is 6-1/2 months!
Here I\'m trying to hang a couple of ADA4817s off a 20-V rail, and my
go-to floating ground generator is getting scarce. razzafrazza%$&@!!
for 20V wouldn\'t this be an alternative?
https://www.st.com/resource/en/datasheet/l2720w.pdf
Looks good but they seem a bit un-confident about the offset voltage
spec...???? it\'s usually somewhere in there
page5: input offset voltage -/+10mV ?
Right. The TCA0372 lists 1mV typ and 15 mV max, when there\'s a wide
spread there I get the impression that the 15mV parts are the real
outlier and don\'t show up much in practice. You could use them for DC
application and expect better and QC out a few boards that got a real
bad one.
When it\'s just -/+10 mV with no typ I get the impression that it\'s all
over the place from device to device, so might not be the best choice of
part for a DC-coupled application with gain.
But interpreting datasheets can be mysterious, I\'d guess the TCA would
not be so popular if it were giving offsets at the far end routinely though.
but max might happen, less than 10mV is better than usually 1mV
occupationally 15mV, you have to design for it unless you want to
start sorting
Beasts like that are (IME) used for things like driving servomotors or
making floating ground/supply rails (my usual application). The motors
are inside some outer FB loop, and nobody cares about a 15-mV offset on
a supply rail.
For the occasional precision application, wrap a chopamp feedback loop
round it.
Or just calibrate out the offset.
Sure, if it sits still. I\'d expect it to walk around a bit, what with
being a power op amp and all. (Widlar put a paper in the ISSC one
year that purported to prove that monolithic voltage regulators with
on-chip pass transistors were impossible due to thermal feedback.
Everybody believed it because it was Widlar. Then he came out with the
LM109/309.)
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com