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Groups > sci.electronics.design > #489092
| From | Joerg <news@analogconsultants.com> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: Diff amps spec at 500ohms plus, why? |
| Date | 2017-12-22 16:57 -0800 |
| Message-ID | <fa5nv7Ft4sjU1@mid.individual.net> (permalink) |
| References | (4 earlier) <880r3dtahda6d21rkiq22ovf363vekh98s@4ax.com> <fa5emlFr5vtU1@mid.individual.net> <922r3d1ofvnjsvdo1fb613f0irc1l294n8@4ax.com> <fa5i1kFrsjlU1@mid.individual.net> <u88r3d5v2f41fmv7hofd2tglej9pv8lhig@4ax.com> |
On 2017-12-22 16:30, John Larkin wrote: > On Fri, 22 Dec 2017 15:16:16 -0800, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-12-22 14:40, John Larkin wrote: [...] >> >>> But it's impressive how often nobody has the answer. A recent question >>> invoked the response "That's an old Burr-Brown part. Nobody knows >>> anything about it." (dual 14-bit TXDAC.) >>> >> >> Or they might say "You have to go to Golden Sunset Senior Center and ask >> for resident Joe Smith". >> >> Just came across the THS6214 which looks more capabable than the others >> but +/-5V would be at the very bottom supply range for this chip: >> >> http://www.ti.com/lit/ds/symlink/ths6214.pdf >> >> It's also long in the tooth. 2009 is almost ancient for telco chips. > > I designed a couple things around the THS3062, which was claimed as > suitable as a VSDL line driver. What I didn't realize is that it's > *only* safe to use as a VSDL line driver. If you use it as a > general-purpose opamp, it tends to fry itself. The latest version of > the data sheet mentions the problem. > That one is a CFB amp. If used as an integrator or even with the slightest capacitive feedback it coan oscillate and unsolder itself. They also don't like capacitive loads but that goes for most high-speed VFB opamps as well. > So be careful! > I will. Sometimes I have the feeling that datasheets are written by marketing types. Why else would anyone spec a diff "driver" at 500, 800 or in some cases even 1000 ohms? It's like specifying a pickup truck's performance with a load of two six-packs in the bed. > IC data sheets are not universally to be believed. Nor are their Spice > models. I usually breadboard a new part. > I might go with the ADA4950 for now and place 10ohms each in series so it won't go berserk when it sees a few pF of capacitive load. Cable is never ideal. Its drive capabilities aren't much to write home about but this is more a proof-of-concept. Later we'll likely try a DSL driver, depending on high much THD and IM performance we end up needing. Sometimes you have to run a really high voltage supply rail and divide the output back down or clamp it. -- Regards, Joerg http://www.analogconsultants.com/
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Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-21 15:48 -0800
Re: Diff amps spec at 500ohms plus, why? George Herold <gherold@teachspin.com> - 2017-12-21 18:53 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 09:31 -0800
Re: Diff amps spec at 500ohms plus, why? Winfield Hill <hill@rowland.harvard.edu> - 2017-12-21 19:48 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 09:34 -0800
Re: Diff amps spec at 500ohms plus, why? bloggs.fredbloggs.fred@gmail.com - 2017-12-24 09:37 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-21 19:55 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-21 19:59 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 09:39 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 12:07 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highland_snip_technology.com> - 2017-12-22 12:54 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 13:29 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highland_snip_technology.com> - 2017-12-22 14:06 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 14:19 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highland_snip_technology.com> - 2017-12-22 14:40 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 15:16 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-22 16:30 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-22 16:57 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-22 20:33 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-23 08:21 -0800
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-23 10:20 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-23 11:33 -0800
Re: Diff amps spec at 500ohms plus, why? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-23 13:56 -0500
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-23 11:08 -0800
Re: Diff amps spec at 500ohms plus, why? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-23 14:11 -0500
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-23 11:42 -0800
Re: Diff amps spec at 500ohms plus, why? LM <sala.nimi@mail.com> - 2017-12-23 21:36 +0200
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-23 12:18 -0800
Diff amps spec at 500ohms plus, why? Klaus Kragelund <klauskvik@hotmail.com> - 2017-12-25 00:56 -0800
Re: Diff amps spec at 500ohms plus, why? krw@notreal.com - 2017-12-25 08:51 -0500
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-25 07:26 -0800
Re: Diff amps spec at 500ohms plus, why? krw@notreal.com - 2017-12-25 10:46 -0500
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-25 07:51 -0800
Re: Diff amps spec at 500ohms plus, why? krw@notreal.com - 2017-12-25 12:53 -0500
Re: Diff amps spec at 500ohms plus, why? John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-25 09:58 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-25 11:39 -0800
Re: Diff amps spec at 500ohms plus, why? whit3rd <whit3rd@gmail.com> - 2017-12-25 17:16 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-27 16:17 -0800
Re: Diff amps spec at 500ohms plus, why? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-12-27 19:06 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-28 00:47 -0800
Re: Diff amps spec at 500ohms plus, why? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-12-27 16:38 -0800
Re: Diff amps spec at 500ohms plus, why? George Herold <gherold@teachspin.com> - 2017-12-27 18:03 -0800
Re: Diff amps spec at 500ohms plus, why? Joerg <news@analogconsultants.com> - 2017-12-28 00:50 -0800
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