A/D converter
in [Design]
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From: Tim Wescott on 9 Apr 2008 11:29 On Wed, 09 Apr 2008 10:12:35 -0500, Palinurus wrote: > GPG wrote: >> >> >> http://www.intersil.com/data/fn/fn3082.pdf >> > - > The 7107 has no provision for display hold. The 7117 does, but is > hard to find these days, and will become more so. As to the MAX1496, > they apparently have a stock of around 100, and once those are gone, it > will be more than 6 months before they crank out another batch. > Obviously not a hot seller, so maybe a prime candidate for obsolescence. AFAIK all Maxim parts are equally "obsolescent". It's been a while since I asked, but when I did Maxim sales people would say "oh, we never obsolete anything". Experience says that's because Maxim never takes anything out of their line -- they just wait longer and longer intervals between actually making any. Design in Maxim parts as a last resort. -- Tim Wescott Control systems and communications consulting http://www.wescottdesign.com Need to learn how to apply control theory in your embedded system? "Applied Control Theory for Embedded Systems" by Tim Wescott Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
From: Robert Lacoste on 9 Apr 2008 12:12 "Palinurus" <disscourn(a)oplink.net> a �crit dans le message de news: lfWdnYpVwbZbBWHanZ2dnUVZ_gmdnZ2d(a)oplink... > I'm looking for a sigma delta 3.5 digit display-type A/D converter with > display hold and on-chip LED drivers. Something like the MAX1496EPI seems > nearly ideal, but I can't find a vendor for it, and am hesitant to commit > to a part which may not be available in small quantities later. The > alternative, I suppose, is to use a dual-slope converter like the ICL7135, > and just bite the bullet as regards board real estate and other problems. 1/ ICL7135 or equivalent = more than $5 per 1000 2/ Microcontroller with 12 bit ADC = around $1 (for example a MC9S08QE8 is around $1,2 per 1k), and you can add a couple of 0,01$ transistors if you need a LED display. Don't ask why these dedicated chips are nearly obsolete, no ? Cheers, Robert
From: qrk on 10 Apr 2008 01:40 On Wed, 09 Apr 2008 10:29:24 -0500, Tim Wescott <tim(a)seemywebsite.com> wrote: >On Wed, 09 Apr 2008 10:12:35 -0500, Palinurus wrote: > >> GPG wrote: >>> >>> >>> http://www.intersil.com/data/fn/fn3082.pdf >>> >> - >> The 7107 has no provision for display hold. The 7117 does, but is >> hard to find these days, and will become more so. As to the MAX1496, >> they apparently have a stock of around 100, and once those are gone, it >> will be more than 6 months before they crank out another batch. >> Obviously not a hot seller, so maybe a prime candidate for obsolescence. > >AFAIK all Maxim parts are equally "obsolescent". It's been a while since >I asked, but when I did Maxim sales people would say "oh, we never >obsolete anything". Experience says that's because Maxim never takes >anything out of their line -- they just wait longer and longer intervals >between actually making any. > >Design in Maxim parts as a last resort. Maxim has obsoleted parts in the past. I was a recipient of them canning the MAX439, a really nice opamp, because they couldn't make it work on a new fab line. The designer of the part took off to the Himalayas never to be heard from again. Linear Tech was very happy to pick up the $50k/yr in business. Maxim took down their letter from the president on their web site a few years ago with the "never have obsoleted a part" statement after I pointed out that fiasco.
From: Spehro Pefhany on 10 Apr 2008 08:33 On Wed, 9 Apr 2008 18:12:11 +0200, "Robert Lacoste" <use-contact-at-www-alciom-com-for-email> wrote: > >"Palinurus" <disscourn(a)oplink.net> a �crit dans le message de news: >lfWdnYpVwbZbBWHanZ2dnUVZ_gmdnZ2d(a)oplink... >> I'm looking for a sigma delta 3.5 digit display-type A/D converter with >> display hold and on-chip LED drivers. Something like the MAX1496EPI seems >> nearly ideal, but I can't find a vendor for it, and am hesitant to commit >> to a part which may not be available in small quantities later. The >> alternative, I suppose, is to use a dual-slope converter like the ICL7135, >> and just bite the bullet as regards board real estate and other problems. > >1/ ICL7135 or equivalent = more than $5 per 1000 >2/ Microcontroller with 12 bit ADC = around $1 (for example a MC9S08QE8 is >around $1,2 per 1k), and you can add a couple of 0,01$ transistors if you >need a LED display. > >Don't ask why these dedicated chips are nearly obsolete, no ? > >Cheers, >Robert The more popular ones are still made in the millions for cheap DVMs and panel meters (hard to meet the high impedance input and reference input requirements with a delta-sigma), but they don't generally feature display hold. I wonder if freezing the RC clock on a 7107 (static display drive) with a BJT would work for him. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Palinurus on 13 Apr 2008 12:18
Spehro Pefhany wrote: > On Wed, 9 Apr 2008 18:12:11 +0200, "Robert Lacoste" > <use-contact-at-www-alciom-com-for-email> wrote: > > >> "Palinurus" <disscourn(a)oplink.net> a �crit dans le message de news: >> lfWdnYpVwbZbBWHanZ2dnUVZ_gmdnZ2d(a)oplink... >> >>> I'm looking for a sigma delta 3.5 digit display-type A/D converter with >>> display hold and on-chip LED drivers. Something like the MAX1496EPI seems >>> nearly ideal, but I can't find a vendor for it, and am hesitant to commit >>> to a part which may not be available in small quantities later. The >>> alternative, I suppose, is to use a dual-slope converter like the ICL7135, >>> and just bite the bullet as regards board real estate and other problems. >>> >> 1/ ICL7135 or equivalent = more than $5 per 1000 >> 2/ Microcontroller with 12 bit ADC = around $1 (for example a MC9S08QE8 is >> around $1,2 per 1k), and you can add a couple of 0,01$ transistors if you >> need a LED display. >> >> Don't ask why these dedicated chips are nearly obsolete, no ? >> >> Cheers, >> Robert >> > > The more popular ones are still made in the millions for cheap DVMs > and panel meters (hard to meet the high impedance input and reference > input requirements with a delta-sigma), but they don't generally > feature display hold. I wonder if freezing the RC clock on a 7107 > (static display drive) with a BJT would work for him. > > Best regards, > Spehro Pefhany > - Nope. You get a random collection of segments, and it behaves badly on restart. No matter, I've decided to go with the ICL7135 anyway, which has at least two second sources. Also, I've thought of a nifty use for the "underrange" output, which will save me a couple of comparators. Screw Maxim. |