reg + reference
in [Design]
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From: krw on 31 Mar 2010 23:53 On Wed, 31 Mar 2010 22:14:16 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:2vt7r5p5qcrd78neuabj8b9gu837pecbt2(a)4ax.com... >> DEC loved wire-wrap, but as logic got faster the impedance and >> crosstalk issues became untenable. PCBs were cheaper anyhow. > >Ironically, ECL came out before TTL. Yes, IBM used all ECL until the mid '80s, then one generation of TTL[*] and back to ECL until CMOS knocked it out permanently. While ECL was faster, TTL has a nasty dI/dt issue. I did MECL 10K designs on wirewrap, too. Worked fine. [*] More precisely Schottky TTL, which is in reality DTL >They routed those with twisted pair. Automated twisted pair wire wrapping >machines -- awesome tech! That was later. Wirewrap was gone by then.
From: JosephKK on 1 Apr 2010 00:21 On Wed, 31 Mar 2010 08:22:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 31 Mar 2010 04:37:14 -0700, >"JosephKK"<quiettechblue(a)yahoo.com> wrote: > >>On Fri, 26 Mar 2010 18:40:33 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Fri, 26 Mar 2010 17:01:38 -0700 (PDT), "langwadt(a)fonz.dk" >>><langwadt(a)fonz.dk> wrote: >>> >>>>On 26 Mar., 22:24, John Larkin >>>><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>> On Fri, 26 Mar 2010 19:21:00 GMT, Jan Panteltje >>>>> >>>>> <pNaonStpealm...(a)yahoo.com> wrote: >>>>> >On a sunny day (Fri, 26 Mar 2010 10:19:55 -0700) it happened John Larkin >>>>> ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>> ><13rpq5lqd1lj1k9flb9orfr2vcl2tuu...(a)4ax.com>: >>>>> >>>>> >>ftp://jjlarkin.lmi.net/V220_reg.JPG >>>>> >>>>> >>John >>>>> >>>>> >No money for a real current source or current mirror? >>>>> >Does that 1M depending on beta circuit change a lot over temperature? >>>>> >Its Vbe will change, so will the Ib. >>>>> >>>>> The current into the reference will be more constant than if I just >>>>> used a resistor with a nominal 0.3 volt drop across it. The BCX71K has >>>>> a very tight beta spec. It would probably be better than using the >>>>> current mirror discussed in another thread recently. And we have >>>>> BCX71Ks in stock for under 4 cents each. >>>>> >>>>> The +15 is not very well regulated, and I'm tight for space. >>>>> >>>>> I guess I could use a depletion mode fet from +15. That's just one >>>>> part. The current regulation would be fair, but I wouldn't have any >>>>> flexibility on setting current. An LND150 is 33 cents, no problem >>>>> there, but Idss is 1 to 3 mA and it may change a bunch with >>>>> temperature. >>>>> >>>>> Or maybe there exists a 3 volt 3-wire reference that would work from >>>>> 3.3 volts. >>>> >>>>use the ~3.3V as reference, measure a 1.2V reference voltage and >>>>correct for it? >>> >>>I could use a 1.2 volt shunt reference, with a reasonable resistor >>>from 3.3, and use an opamp to scale the 1.2 up to 3. More parts! The >>>National low-dropout reference is ideal, if it doesn't oscillate. >>> >>>> >>>>> >>>>> This will be the ADC voltage reference for an NXP ARM processor. I'm >>>>> doing a 12-channel 4-20 mA thing, electrically isolated per channel, >>>>> with an ARM per channel. The ARM and other stuff might need 45 mA or >>>>> so, less if we can sleep the code a lot. >>>> >>>>why not pick an ARM with a build in reference? something like >>>>stm32... ? >>>>12 bits too, think the nxp is only 10bits >>> >>>The NXP LPC1768 we're going to use has a 12 bit mux'd ADC and a 10 bit >>>DAC, and all the other stuff like ram, flash, SPI we need. It's a 100 >>>MHz CPU with single-cycle multiply, pretty impressive for around $7. >>>We're going to be running a couple of PID loops as fast as the ADC can >>>feed us data, 100K hits a second maybe. >>> >>>Some of the ST parts look nice, but we already have the compiler/jtag >>>infrastructure in place for the NXP, and we're blinking LEDs, so we'll >>>stick with that. >>> >>>> >>>>I'm sure analog has some too >>> >>>ARM seems to have won the embedded game. Freescale/Coldfire is rumored >>>to be seriously ill. >>> >>>John >> >>Could you elucidate on the coldfire being seriously ill? Preferably with >>references / links, as it may impact my employer. > >www.google.com. > > >John Many device lines have lived decades under similar death threat. If you cannot come up with better than that, i have no need to worry.
From: JosephKK on 1 Apr 2010 00:27 On Wed, 31 Mar 2010 18:34:57 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 31 Mar 2010 17:55:20 -0500, "krw(a)att.bizzzzzzzzzzzz" ><krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Wed, 31 Mar 2010 05:24:45 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >> >>>On Sat, 27 Mar 2010 08:49:16 -0700, Joerg <invalid(a)invalid.invalid> wrote: >>> >>>>Nico Coesel wrote: >>>>> Joerg <invalid(a)invalid.invalid> wrote: >>>>> >>>>>> It's like press-fit where I sat in a meting where a company pitched it >>>>>> to a client. Tappa-di-tap went my calculator. "I calculated that 3 out >>>>>> of all the contacts will be open. Can you tell us which ones those will >>>>>> be?". The meeting and the sales pitch ended that instant ... >>>>> >>>>> Sorry but that must be some calculating error on your side. All PABXes >>>>> I've seen had press-fit backplanes for a very good reason >>>>> (reliability). But just like soldering and crimping connections >>>>> mounting press-fit is something that needs to be done right. >>>>> >>>> >>>>On the first series it had been done by the pros. Sorry, but my >>>>experience with pressfit is not positive. Not as bad as with wire-wrap >>>>but close. >>> >>>Hmm. My experience with wire-wrap has been uniformly good. Also like >>>soldering and crimping, it must be done right. 30+ years ago i was certified >>>for solder, wire-wrap and crimp. >> >>WireWrap was used in a *lot* of places where reliability was the primary >>importance. Mainframe backplanes were all wire-wrapped at one time. >> > >DEC loved wire-wrap, but as logic got faster the impedance and >crosstalk issues became untenable. PCBs were cheaper anyhow. > >John > Also density issues and thermal management were driving issues; both still are today 30 years later (today).
From: Phil Hobbs on 1 Apr 2010 09:26 On 3/31/2010 9:34 PM, John Larkin wrote: > On Wed, 31 Mar 2010 17:55:20 -0500, "krw(a)att.bizzzzzzzzzzzz" > <krw(a)att.bizzzzzzzzzzzz> wrote: > >> On Wed, 31 Mar 2010 05:24:45 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >> >>> On Sat, 27 Mar 2010 08:49:16 -0700, Joerg<invalid(a)invalid.invalid> wrote: >>> >>>> Nico Coesel wrote: >>>>> Joerg<invalid(a)invalid.invalid> wrote: >>>>> >>>>>> It's like press-fit where I sat in a meting where a company pitched it >>>>>> to a client. Tappa-di-tap went my calculator. "I calculated that 3 out >>>>>> of all the contacts will be open. Can you tell us which ones those will >>>>>> be?". The meeting and the sales pitch ended that instant ... >>>>> >>>>> Sorry but that must be some calculating error on your side. All PABXes >>>>> I've seen had press-fit backplanes for a very good reason >>>>> (reliability). But just like soldering and crimping connections >>>>> mounting press-fit is something that needs to be done right. >>>>> >>>> >>>> On the first series it had been done by the pros. Sorry, but my >>>> experience with pressfit is not positive. Not as bad as with wire-wrap >>>> but close. >>> >>> Hmm. My experience with wire-wrap has been uniformly good. Also like >>> soldering and crimping, it must be done right. 30+ years ago i was certified >>> for solder, wire-wrap and crimp. >> >> WireWrap was used in a *lot* of places where reliability was the primary >> importance. Mainframe backplanes were all wire-wrapped at one time. >> > > DEC loved wire-wrap, but as logic got faster the impedance and > crosstalk issues became untenable. PCBs were cheaper anyhow. > > John > > When I was a grad student, Grinnell donated one of their big rack-mounted frame buffer/video format converter gizmos to us. Huge big wire-wrapped backplane, even in an allegedly production box. I thought that was weird in 1985. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Phil Hobbs on 1 Apr 2010 09:27
On 3/31/2010 11:53 PM, krw(a)att.bizzzzzzzzzzzz wrote: > On Wed, 31 Mar 2010 22:14:16 -0500, "Tim Williams"<tmoranwms(a)charter.net> > wrote: > >> "John Larkin"<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >> news:2vt7r5p5qcrd78neuabj8b9gu837pecbt2(a)4ax.com... >>> DEC loved wire-wrap, but as logic got faster the impedance and >>> crosstalk issues became untenable. PCBs were cheaper anyhow. >> >> Ironically, ECL came out before TTL. > > Yes, IBM used all ECL until the mid '80s, then one generation of TTL[*] and > back to ECL until CMOS knocked it out permanently. While ECL was faster, TTL > has a nasty dI/dt issue. I did MECL 10K designs on wirewrap, too. Worked > fine. > I think the 3090 was the last ECL beast, and they went right to CMOS. I was sort of in the middle of that, circa 1990. Cheers Phil Hobbs > [*] More precisely Schottky TTL, which is in reality DTL > >> They routed those with twisted pair. Automated twisted pair wire wrapping >> machines -- awesome tech! > > That was later. Wirewrap was gone by then. -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |