On 2017-11-21, Joerg <news@analogconsultants.com> wrote:> On 2017-11-21 11:35, Winfield Hill wrote: >> John Larkin wrote... >>> >>> The ancient LM324 has PNP input transistors, and the >>> safe input voltages can go to +32 irrespective of V+. >> > > The datasheet says "Don't do that" though. Looking at the innards on > page 4 it seems you'd hit a diode path to V+: > > http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdfuse the TI part. http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf -- This email has not been checked by half-arsed antivirus software
Need Op Amp for design
Started by ●November 19, 2017
Reply by ●November 23, 20172017-11-23
Reply by ●November 23, 20172017-11-23
On 2017-11-22 22:22, Jasen Betts wrote:> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >> On 2017-11-21 11:35, Winfield Hill wrote: >>> John Larkin wrote... >>>> >>>> The ancient LM324 has PNP input transistors, and the >>>> safe input voltages can go to +32 irrespective of V+. >>> >> >> The datasheet says "Don't do that" though. Looking at the innards on >> page 4 it seems you'd hit a diode path to V+: >> >> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf > > use the TI part. > > http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >For hobby or small runs it's ok. With contract assemblers it can be dicey. The worst I had so far was a capacitor with very low leakage. The exact part was described and ECO-released yet one day all units in a shipment failed inspection. "But our sales rep assured us the lower cost cap is identical ...". IIRC about 4000 boards had to be scrapped and the contract assembler ate the cost. That didn't make up for missed deliveries and sales delays though. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 23, 20172017-11-23
On Fri, 24 Nov 2017 01:54:57 +1000, Joerg <news@analogconsultants.com> wrote:> On 2017-11-22 22:22, Jasen Betts wrote: >> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>> On 2017-11-21 11:35, Winfield Hill wrote: >>>> John Larkin wrote... >>>>> >>>>> The ancient LM324 has PNP input transistors, and the >>>>> safe input voltages can go to +32 irrespective of V+. >>>> >>> >>> The datasheet says "Don't do that" though. Looking at the innards on >>> page 4 it seems you'd hit a diode path to V+: >>> >>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >> >> use the TI part. >> >> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >>There is also a lower power version of the lm324 / 358 from ti. It's imaginatively called an LP324 and LP358 -- The latest set of Shadow Broker tools shows the UK, USA, Canada, Australian and New Zealand spy agencies were hacking into domestic home routers. Who gave them permission to spy on our kids?
Reply by ●November 24, 20172017-11-24
On 2017-11-23 17:54, David Eather wrote:> On Fri, 24 Nov 2017 01:54:57 +1000, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-11-22 22:22, Jasen Betts wrote: >>> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>>> On 2017-11-21 11:35, Winfield Hill wrote: >>>>> John Larkin wrote... >>>>>> >>>>>> The ancient LM324 has PNP input transistors, and the >>>>>> safe input voltages can go to +32 irrespective of V+. >>>>> >>>> >>>> The datasheet says "Don't do that" though. Looking at the innards on >>>> page 4 it seems you'd hit a diode path to V+: >>>> >>>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >>>> >>> >>> use the TI part. >>> >>> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >>> > > There is also a lower power version of the lm324 / 358 from ti. It's > imaginatively called an LP324 and LP358 >That could be a good contender if it doesn't have any brethens with the same name but less votage tolerance in shut-down. The question in this case though is what the leakage current of the highly stretched BE junction will be. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 24, 20172017-11-24
On Tue, 21 Nov 2017 12:41:31 -0800, Joerg <news@analogconsultants.com> wrote:>On 2017-11-21 12:28, John Larkin wrote: >> On Tue, 21 Nov 2017 12:05:59 -0800, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2017-11-21 11:35, Winfield Hill wrote: >>>> John Larkin wrote... >>>>> >>>>> The ancient LM324 has PNP input transistors, and the >>>>> safe input voltages can go to +32 irrespective of V+. >>>> >>> >>> The datasheet says "Don't do that" though. Looking at the innards on >>> page 4 it seems you'd hit a diode path to V+: >>> >>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >>> >>> Quote page 4, footnote (1) "Neither of the input voltages must exceed >>> the magnitude of (VCC+) or (VCC-)". >>> >>> >> >> The original National data sheet specifically allows +32 irrespective >> of V+. Can't trust those eye-talian chips. [1] >> >> But DO NOT allow an input to go below V-, operating. All sorts of >> weird stuff will happen. >> >>>> I also thought of PNP-input single-supply op-amps as >>>> a good solution, but the O.P. seems not to notice. >>>> >>> >>> >>> Even if there wasn't a diode path, wouldn't the then reversed BE >>> junction zener somewhere around 6V? >> >> PNPs tend to have higher zener voltage. The 324 must have some >> special, old-fashioned diffusion. >> >> [1] And why do we sell them good wheat for a few dollars a bushel, and >> let them add water, take out the water, and sell it back to us for $8 >> a pound? >> > >Worse. We sell them hide and they send Gucci stuff back to 5th Avenue >that costs 1000x of what we sent.We also sell them grain, they add water, and they ship it back to us as really, really bad beer. -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 24, 20172017-11-24
On Thu, 23 Nov 2017 07:54:57 -0800, Joerg <news@analogconsultants.com> wrote:>On 2017-11-22 22:22, Jasen Betts wrote: >> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>> On 2017-11-21 11:35, Winfield Hill wrote: >>>> John Larkin wrote... >>>>> >>>>> The ancient LM324 has PNP input transistors, and the >>>>> safe input voltages can go to +32 irrespective of V+. >>>> >>> >>> The datasheet says "Don't do that" though. Looking at the innards on >>> page 4 it seems you'd hit a diode path to V+: >>> >>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >> >> use the TI part. >> >> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >> > >For hobby or small runs it's ok. With contract assemblers it can be >dicey.NEVER allow a CM to substitute parts! -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●November 24, 20172017-11-24
John Larkin <jjlarkin@highlandtechnology.com> writes:> On Thu, 23 Nov 2017 07:54:57 -0800, Joerg <news@analogconsultants.com> > wrote: > >>On 2017-11-22 22:22, Jasen Betts wrote: >>> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>>> On 2017-11-21 11:35, Winfield Hill wrote: >>>>> John Larkin wrote... >>>>>> >>>>>> The ancient LM324 has PNP input transistors, and the >>>>>> safe input voltages can go to +32 irrespective of V+. >>>>> >>>> >>>> The datasheet says "Don't do that" though. Looking at the innards on >>>> page 4 it seems you'd hit a diode path to V+: >>>> >>>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >>> >>> use the TI part. >>> >>> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >>> >> >>For hobby or small runs it's ok. With contract assemblers it can be >>dicey. > > NEVER allow a CM to substitute parts!Yes, quite, I am amazed that Jeorg allows this to happen actually given his previous postings here. (Regarding documentation control, certifications, procedures, etc etc). Also it seems rather unfair on the original manufacturer of the part. As soon as someone releases a clone, only hobbyists should then use the original? -- John Devereux
Reply by ●November 24, 20172017-11-24
On 2017-11-24 08:05, John Larkin wrote:> On Tue, 21 Nov 2017 12:41:31 -0800, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-11-21 12:28, John Larkin wrote: >>> On Tue, 21 Nov 2017 12:05:59 -0800, Joerg <news@analogconsultants.com> >>> wrote: >>> >>>> On 2017-11-21 11:35, Winfield Hill wrote:[...]>>> The original National data sheet specifically allows +32 irrespective >>> of V+. Can't trust those eye-talian chips. [1] >>> >>> But DO NOT allow an input to go below V-, operating. All sorts of >>> weird stuff will happen. >>> >>>>> I also thought of PNP-input single-supply op-amps as >>>>> a good solution, but the O.P. seems not to notice. >>>>> >>>> >>>> >>>> Even if there wasn't a diode path, wouldn't the then reversed BE >>>> junction zener somewhere around 6V? >>> >>> PNPs tend to have higher zener voltage. The 324 must have some >>> special, old-fashioned diffusion. >>> >>> [1] And why do we sell them good wheat for a few dollars a bushel, and >>> let them add water, take out the water, and sell it back to us for $8 >>> a pound? >>> >> >> Worse. We sell them hide and they send Gucci stuff back to 5th Avenue >> that costs 1000x of what we sent. > > We also sell them grain, they add water, and they ship it back to us > as really, really bad beer. >Peroni isn't great but ok on a really hot day. Though once you start home-brewing almost none of the store-bought beer seems up to snuff anymore. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 24, 20172017-11-24
On 2017-11-24 08:06, John Larkin wrote:> On Thu, 23 Nov 2017 07:54:57 -0800, Joerg <news@analogconsultants.com> > wrote: > >> On 2017-11-22 22:22, Jasen Betts wrote: >>> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>>> On 2017-11-21 11:35, Winfield Hill wrote: >>>>> John Larkin wrote... >>>>>> >>>>>> The ancient LM324 has PNP input transistors, and the >>>>>> safe input voltages can go to +32 irrespective of V+. >>>>> >>>> >>>> The datasheet says "Don't do that" though. Looking at the innards on >>>> page 4 it seems you'd hit a diode path to V+: >>>> >>>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >>> >>> use the TI part. >>> >>> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >>> >> >> For hobby or small runs it's ok. With contract assemblers it can be >> dicey. > > NEVER allow a CM to substitute parts! >My client explicitly didn't allow that. Certainly not for this cap because there was a thorough warning about it in the module spec I always write during designs (whether a client wants one or not). Yet the way things sometimes go in far-away lands ... -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●November 24, 20172017-11-24
On 2017-11-24 08:18, John Devereux wrote:> John Larkin <jjlarkin@highlandtechnology.com> writes: > >> On Thu, 23 Nov 2017 07:54:57 -0800, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2017-11-22 22:22, Jasen Betts wrote: >>>> On 2017-11-21, Joerg <news@analogconsultants.com> wrote: >>>>> On 2017-11-21 11:35, Winfield Hill wrote: >>>>>> John Larkin wrote... >>>>>>> >>>>>>> The ancient LM324 has PNP input transistors, and the >>>>>>> safe input voltages can go to +32 irrespective of V+. >>>>>> >>>>> >>>>> The datasheet says "Don't do that" though. Looking at the innards on >>>>> page 4 it seems you'd hit a diode path to V+: >>>>> >>>>> http://www.st.com/content/ccc/resource/technical/document/datasheet/bd/fc/46/43/26/8f/40/7f/CD00001046.pdf/files/CD00001046.pdf/jcr:content/translations/en.CD00001046.pdf >>>> >>>> use the TI part. >>>> >>>> http://www.ti.com/lit/ds/snosc16d/snosc16d.pdf >>>> >>> >>> For hobby or small runs it's ok. With contract assemblers it can be >>> dicey. >> >> NEVER allow a CM to substitute parts! > > Yes, quite, I am amazed that Jeorg allows this to happen actually given > his previous postings here. (Regarding documentation control, > certifications, procedures, etc etc). >As I wrote I didn't allow it and neither did my client. The CM folks took it upon themselves to "cost-optimize". Which is why they had to eat the cost for an expedited re-run and fast air-shipment.> Also it seems rather unfair on the original manufacturer of the part. As > soon as someone releases a clone, only hobbyists should then use the > original? >In this case it isn't a clone and if one knows about it then IMO one needs to point out the risk. The other question in this case is that even for the versions that allow an unusually high reverse Vbe there is no spec in the datasheets about the maximum leakage current that will flow, AFAIK. Li-Ion protection is a pretty serious matter, not something to take lightly. -- Regards, Joerg http://www.analogconsultants.com/
