On a sunny day (Mon, 23 Jul 2012 21:22:42 -0700) it happened Robert Baer <robertbaer@localnet.com> wrote in <JKmdnQgRvqaIvpPNnZ2dnUVZ_g6dnZ2d@posted.localnet>:>Jan Panteltje wrote: >> On a sunny day (Mon, 23 Jul 2012 01:16:24 -0700) it happened Robert Baer >> <robertbaer@localnet.com> wrote in >> <BeCdnSnrv6HGlZDNnZ2dnUVZ_qudnZ2d@posted.localnet>: >> >>> Zeners all seem to behave: quiet, no oscillation IF run at or near >>> the spec current (usually in the tens of mA). >>> But, if one needs to run them at low currents (say 10uA to 500uA) >>> then _watch_out_! >>> Some brands at certain voltages are extremely noisy and subject to >>> oscillation. >>> The waveforms seen at low currents (2-50uA) look like randumb >>> sawtooth generation, and as the current is increased the amplitude and >>> probability increases (do NOT want to say "frequency" as that gives >>> wrong impression). >>> Then this "converts" to random noise. >>> Eventually, there are "bursts" of NO noise. Then at higher current, >>> noise bursts decrease in "frequency" and amplitude. >>> >>> That is what i see in general. >>> However, i have found two zeners that, on a curve tracer, one sees >>> little if any noise or spikes mentioned. >>> NOW for the question: >>> How can one test these particular zeners to ensure they do not or >>> will not oscillate? >>> * >>> Yes, there are zeners made for low noise and those have a much lower >>> spec current, BUT i cannot afford to have the factory dig the silicon >>> mines, etc much less the high $$. >> >> I do not normally use zeners for reference, just for over voltage protection. >> For reference you probably want bandgap based chips. >> There are some very low power reference chips. >> > Reference? Said nothing about that; app is for voltage regulation but >zener pass current must be low.Regulation implies reference in thsi context.> >
Zener noise / oscillations
Started by ●July 23, 2012
Reply by ●July 24, 20122012-07-24
Reply by ●July 24, 20122012-07-24
On a sunny day (Mon, 23 Jul 2012 21:26:50 -0700) it happened Robert Baer <robertbaer@localnet.com> wrote in <JKmdnQsRvqaQuZPNnZ2dnUVZ_g6dnZ2d@posted.localnet>:>Jan Panteltje wrote: >> On a sunny day (Mon, 23 Jul 2012 14:53:16 +0100) it happened John Devereux >> <john@devereux.me.uk> wrote in<87sjci37oz.fsf@devereux.me.uk>: >> >>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>> >>>> On a sunny day (Mon, 23 Jul 2012 01:16:24 -0700) it happened Robert Baer >>>> <robertbaer@localnet.com> wrote in >>>> <BeCdnSnrv6HGlZDNnZ2dnUVZ_qudnZ2d@posted.localnet>: >>>> >>>>> Zeners all seem to behave: quiet, no oscillation IF run at or near >>>>> the spec current (usually in the tens of mA). >>>>> But, if one needs to run them at low currents (say 10uA to 500uA) >>>>> then _watch_out_! >>>>> Some brands at certain voltages are extremely noisy and subject to >>>>> oscillation. >>>>> The waveforms seen at low currents (2-50uA) look like randumb >>>>> sawtooth generation, and as the current is increased the amplitude and >>>>> probability increases (do NOT want to say "frequency" as that gives >>>>> wrong impression). >>>>> Then this "converts" to random noise. >>>>> Eventually, there are "bursts" of NO noise. Then at higher current, >>>>> noise bursts decrease in "frequency" and amplitude. >>>>> >>>>> That is what i see in general. >>>>> However, i have found two zeners that, on a curve tracer, one sees >>>>> little if any noise or spikes mentioned. >>>>> NOW for the question: >>>>> How can one test these particular zeners to ensure they do not or >>>>> will not oscillate? >>>>> * >>>>> Yes, there are zeners made for low noise and those have a much lower >>>>> spec current, BUT i cannot afford to have the factory dig the silicon >>>>> mines, etc much less the high $$. >>>> >>>> I do not normally use zeners for reference, just for over voltage protection. >>>> For reference you probably want bandgap based chips. >>>> There are some very low power reference chips. >>> >>> Bandgap ones are more convenient. But the very best semiconductor >>> references in terms of noise and stability are those based on zeners. >> >> At 2-50uA? > My app is only for voltage regulation, not reference purposes; zener >current to range from 2-500uA. > Gotta be cheeeep 1-3 cents.If you put 2 coins of the right meterial on top of each other you get a 2 cent? worth voltage. :-)
Reply by ●July 24, 20122012-07-24
On a sunny day (Mon, 23 Jul 2012 11:55:53 -0700) it happened Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in <bb7r08ligkg2e6k6qf7fkv82f71rfk60n2@4ax.com>:>I've done bandgaps on CMOS processes... 100uA total operating current. >My bag of tricks includes producing other voltages than the standard >1.25V/2.5V... handy when you have a low voltage supply... I have one >architecture that goes stable and flat output of +1V, when VCC=1.2VI am using the Microchip MPC1525 refernce, it outputs 2.5 V while using 100uA, drop out voltage is typical 137 mV @ 2 mA out.
Reply by ●July 24, 20122012-07-24
On a sunny day (Mon, 23 Jul 2012 21:56:19 -0700) it happened Robert Baer <robertbaer@localnet.com> wrote in <y4CdnbubSZdrt5PNnZ2dnUVZ_rGdnZ2d@posted.localnet>:>Jim Thompson wrote: >> On Mon, 23 Jul 2012 18:12:40 +0100, John Devereux >> <john@devereux.me.uk> wrote: >> >>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>> >>>> On a sunny day (Mon, 23 Jul 2012 14:53:16 +0100) it happened John Devereux >>>> <john@devereux.me.uk> wrote in<87sjci37oz.fsf@devereux.me.uk>: >>>> >>>>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>>>> >>>>>> On a sunny day (Mon, 23 Jul 2012 01:16:24 -0700) it happened Robert Baer >>>>>> <robertbaer@localnet.com> wrote in >>>>>> <BeCdnSnrv6HGlZDNnZ2dnUVZ_qudnZ2d@posted.localnet>: >>>>>> >>>>>>> Zeners all seem to behave: quiet, no oscillation IF run at or near >>>>>>> the spec current (usually in the tens of mA). >>>>>>> But, if one needs to run them at low currents (say 10uA to 500uA) >>>>>>> then _watch_out_! >>>>>>> Some brands at certain voltages are extremely noisy and subject to >>>>>>> oscillation. >>>>>>> The waveforms seen at low currents (2-50uA) look like randumb >>>>>>> sawtooth generation, and as the current is increased the amplitude and >>>>>>> probability increases (do NOT want to say "frequency" as that gives >>>>>>> wrong impression). >>>>>>> Then this "converts" to random noise. >>>>>>> Eventually, there are "bursts" of NO noise. Then at higher current, >>>>>>> noise bursts decrease in "frequency" and amplitude. >>>>>>> >>>>>>> That is what i see in general. >>>>>>> However, i have found two zeners that, on a curve tracer, one sees >>>>>>> little if any noise or spikes mentioned. >>>>>>> NOW for the question: >>>>>>> How can one test these particular zeners to ensure they do not or >>>>>>> will not oscillate? >>>>>>> * >>>>>>> Yes, there are zeners made for low noise and those have a much lower >>>>>>> spec current, BUT i cannot afford to have the factory dig the silicon >>>>>>> mines, etc much less the high $$. >>>>>> >>>>>> I do not normally use zeners for reference, just for over voltage protection. >>>>>> For reference you probably want bandgap based chips. >>>>>> There are some very low power reference chips. >>>>> >>>>> Bandgap ones are more convenient. But the very best semiconductor >>>>> references in terms of noise and stability are those based on zeners. >>>> >>>> At 2-50uA? >>> >>> Not as far as I know - usually about 5mA and ~6-7V. Like I said, not >>> very convenient. >> >> I've done bandgaps on CMOS processes... 100uA total operating current. >> My bag of tricks includes producing other voltages than the standard >> 1.25V/2.5V... handy when you have a low voltage supply... I have one >> architecture that goes stable and flat output of +1V, when VCC=1.2V >> >> ...Jim Thompson > Now THAT must be very handy!The PIC 18F... has an internal programable bandgap reference, you can select for 1.024V, and 2 or 3, or 4 x that, so up to 4.096 V, and uses very low power. It can probably replace the rest of your circuit too ;-)
Reply by ●July 24, 20122012-07-24
George Herold <gherold@teachspin.com> wrote: [...]> > Though all of this depends on the power rating of the diode too.Current per cross-sectional seems to be the critical parameter for most device measurements, I would be very surprised if that didn't apply to zeners too. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
Reply by ●July 24, 20122012-07-24
"Robert Baer" <robertbaer@localnet.com> wrote in message news:y4CdnbWbSZcVtpPNnZ2dnUVZ_rGdnZ2d@posted.localnet...> Yes, a TL431 is cheap but the minimal standing current is way above what > is needed.1mA? TLV431 is 100uA and 1.240V, much improved. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●July 24, 20122012-07-24
On Mon, 23 Jul 2012 21:56:19 -0700, Robert Baer <robertbaer@localnet.com> wrote:>Jim Thompson wrote: >> On Mon, 23 Jul 2012 18:12:40 +0100, John Devereux >> <john@devereux.me.uk> wrote: >> >>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>> >>>> On a sunny day (Mon, 23 Jul 2012 14:53:16 +0100) it happened John Devereux >>>> <john@devereux.me.uk> wrote in<87sjci37oz.fsf@devereux.me.uk>: >>>> >>>>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>>>> >>>>>> On a sunny day (Mon, 23 Jul 2012 01:16:24 -0700) it happened Robert Baer >>>>>> <robertbaer@localnet.com> wrote in >>>>>> <BeCdnSnrv6HGlZDNnZ2dnUVZ_qudnZ2d@posted.localnet>: >>>>>> >>>>>>> Zeners all seem to behave: quiet, no oscillation IF run at or near >>>>>>> the spec current (usually in the tens of mA). >>>>>>> But, if one needs to run them at low currents (say 10uA to 500uA) >>>>>>> then _watch_out_! >>>>>>> Some brands at certain voltages are extremely noisy and subject to >>>>>>> oscillation. >>>>>>> The waveforms seen at low currents (2-50uA) look like randumb >>>>>>> sawtooth generation, and as the current is increased the amplitude and >>>>>>> probability increases (do NOT want to say "frequency" as that gives >>>>>>> wrong impression). >>>>>>> Then this "converts" to random noise. >>>>>>> Eventually, there are "bursts" of NO noise. Then at higher current, >>>>>>> noise bursts decrease in "frequency" and amplitude. >>>>>>> >>>>>>> That is what i see in general. >>>>>>> However, i have found two zeners that, on a curve tracer, one sees >>>>>>> little if any noise or spikes mentioned. >>>>>>> NOW for the question: >>>>>>> How can one test these particular zeners to ensure they do not or >>>>>>> will not oscillate? >>>>>>> * >>>>>>> Yes, there are zeners made for low noise and those have a much lower >>>>>>> spec current, BUT i cannot afford to have the factory dig the silicon >>>>>>> mines, etc much less the high $$. >>>>>> >>>>>> I do not normally use zeners for reference, just for over voltage protection. >>>>>> For reference you probably want bandgap based chips. >>>>>> There are some very low power reference chips. >>>>> >>>>> Bandgap ones are more convenient. But the very best semiconductor >>>>> references in terms of noise and stability are those based on zeners. >>>> >>>> At 2-50uA? >>> >>> Not as far as I know - usually about 5mA and ~6-7V. Like I said, not >>> very convenient. >> >> I've done bandgaps on CMOS processes... 100uA total operating current. >> My bag of tricks includes producing other voltages than the standard >> 1.25V/2.5V... handy when you have a low voltage supply... I have one >> architecture that goes stable and flat output of +1V, when VCC=1.2V >> >> ...Jim Thompson > Now THAT must be very handy!Yep. Low voltage, low current is in vogue. I've done whole chips at 5uA. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●July 24, 20122012-07-24
On Mon, 23 Jul 2012 21:58:46 -0700, Robert Baer <robertbaer@localnet.com> wrote:>bitterlemon40@yahoo.ie wrote: >> You can heat treat zener diodes (by passing a lot of current through them) for use in saw-tooth oscillator circuits. Obviously if you that you are causing poorly controlled physical changes of the semiconductor properties. You know a TL431 shunt regulator costs so little these days that you should use it in your circuits in preference to a zener diode. It is so much better and 1960's style voltage regulation is not such a great idea these days. > Yes, a TL431 is cheap but the minimal standing current is way above >what is needed.Isn't there a low current, lower voltage (1.25V) available? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●July 24, 20122012-07-24
On Monday, July 23, 2012 4:16:24 AM UTC-4, Robert Baer wrote:> Zeners all seem to behave: quiet, no oscillation IF run at or near > the spec current (usually in the tens of mA). > But, if one needs to run them at low currents (say 10uA to 500uA) > then _watch_out_! > Some brands at certain voltages are extremely noisy and subject to > oscillation. > The waveforms seen at low currents (2-50uA) look like randumb > sawtooth generation, and as the current is increased the amplitude and > probability increases (do NOT want to say "frequency" as that gives > wrong impression). > Then this "converts" to random noise. > Eventually, there are "bursts" of NO noise. Then at higher current, > noise bursts decrease in "frequency" and amplitude. > > That is what i see in general. > However, i have found two zeners that, on a curve tracer, one sees > little if any noise or spikes mentioned. > NOW for the question: > How can one test these particular zeners to ensure they do not or > will not oscillate? > * > Yes, there are zeners made for low noise and those have a much lower > spec current, BUT i cannot afford to have the factory dig the silicon > mines, etc much less the high $$.For test purposes as far as detecting the negative resistance region, I would think the standard topology of high impedance source charging the parallel combination of zener || C should bring it out. There you would monitor zener current.
Reply by ●July 25, 20122012-07-25
Jan Panteltje wrote:> On a sunny day (Mon, 23 Jul 2012 21:26:50 -0700) it happened Robert Baer > <robertbaer@localnet.com> wrote in > <JKmdnQsRvqaQuZPNnZ2dnUVZ_g6dnZ2d@posted.localnet>: > >> Jan Panteltje wrote: >>> On a sunny day (Mon, 23 Jul 2012 14:53:16 +0100) it happened John Devereux >>> <john@devereux.me.uk> wrote in<87sjci37oz.fsf@devereux.me.uk>: >>> >>>> Jan Panteltje<pNaonStpealmtje@yahoo.com> writes: >>>> >>>>> On a sunny day (Mon, 23 Jul 2012 01:16:24 -0700) it happened Robert Baer >>>>> <robertbaer@localnet.com> wrote in >>>>> <BeCdnSnrv6HGlZDNnZ2dnUVZ_qudnZ2d@posted.localnet>: >>>>> >>>>>> Zeners all seem to behave: quiet, no oscillation IF run at or near >>>>>> the spec current (usually in the tens of mA). >>>>>> But, if one needs to run them at low currents (say 10uA to 500uA) >>>>>> then _watch_out_! >>>>>> Some brands at certain voltages are extremely noisy and subject to >>>>>> oscillation. >>>>>> The waveforms seen at low currents (2-50uA) look like randumb >>>>>> sawtooth generation, and as the current is increased the amplitude and >>>>>> probability increases (do NOT want to say "frequency" as that gives >>>>>> wrong impression). >>>>>> Then this "converts" to random noise. >>>>>> Eventually, there are "bursts" of NO noise. Then at higher current, >>>>>> noise bursts decrease in "frequency" and amplitude. >>>>>> >>>>>> That is what i see in general. >>>>>> However, i have found two zeners that, on a curve tracer, one sees >>>>>> little if any noise or spikes mentioned. >>>>>> NOW for the question: >>>>>> How can one test these particular zeners to ensure they do not or >>>>>> will not oscillate? >>>>>> * >>>>>> Yes, there are zeners made for low noise and those have a much lower >>>>>> spec current, BUT i cannot afford to have the factory dig the silicon >>>>>> mines, etc much less the high $$. >>>>> >>>>> I do not normally use zeners for reference, just for over voltage protection. >>>>> For reference you probably want bandgap based chips. >>>>> There are some very low power reference chips. >>>> >>>> Bandgap ones are more convenient. But the very best semiconductor >>>> references in terms of noise and stability are those based on zeners. >>> >>> At 2-50uA? >> My app is only for voltage regulation, not reference purposes; zener >> current to range from 2-500uA. >> Gotta be cheeeep 1-3 cents. > > If you put 2 coins of the right meterial on top of each other you get a 2 cent? > worth voltage. > :-)Might not work with the counterfeit coins the US mint makes these daze..
