On Wednesday, March 1, 2023 at 4:51:01 PM UTC+11, Jan Panteltje wrote:> On a sunny day (Tue, 28 Feb 2023 08:45:28 -0800) it happened John Larkin <jla...@highlandSNIPMEtechnology.com> wrote in <gpbsvhl4gjtjc4ra4...@4ax.com>: > >On Tue, 28 Feb 2023 16:33:40 GMT, Jan Panteltje <al...@comet.invalid> wrote: > >>On a sunny day (Tue, 28 Feb 2023 08:00:50 -0800) it happened John Larkin <jla...@highlandSNIPMEtechnology.com> wrote in <j89svh5rd7a465i52...@4ax.com>: > >>>On Tue, 28 Feb 2023 15:48:10 GMT, Jan Panteltje <al...@comet.invalid> wrote: > >>>>On a sunny day (Tue, 28 Feb 2023 07:05:54 -0800 (PST)) it happened "neo5...@gmail.com" <neo5...@gmail.com> wrote in <2728e43f-ea4f-4df3...@googlegroups.com>: > >>>> > >>>>>Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I don't know what kind of power it can handle or how stable it is when used this way. > >>>> > >>>>If you connect the collector to the base as well, the thing can take more current > >>>> > >>>>Now 200 mA Imax collector current counts, zenering about .7 V gives .7 * .2 = .140 mW > >>>>Note that Vbe sat may be as high as .95 V at 90 mA Ic, even higher at > >>>>Also Vbe is very temperature dependent. > >>>>See datasheet. > >>>>If you want a precise voltage better use something else. > >>>> > >>>>A big Si diode used in forward direction will give the same effect, voltage drop and temperature problems. > >>> > >>>But that's not a zener. > >> > >>Ah, seems he wants it reverse biased, my error. > >>Using the thing that way may cause it to die after a while :-) > > > >It would be an interesting experiment to measure the b-e zener voltage long-term, at a couple of currents. Beta degrades in a transistor if > >the base is zenered, so something is going on.Probably nothing that messes up the breakdown voltage. The 1960's J.,Sci.Instrum. paper touted it as a cheap stable reference. There's a grab-bag National Semiconductor application note for the LM339 that tells much the same story on page 30. https://www.ti.com/lit/an/snoa654a/snoa654a.pdf "Experimental data has shown that any of National's process 21 transistors which have been selected for low reverse beta (βR <.25) can be used quite satisfactorily as a zero T.C. Zener. When connected as shown in Figure 37, the T.C. of the base-emitter Zener voltage is exactly cancelled by the T.C. of the forward biased base-collector junction if biased at 1.5 mA. The diode can be properly biased from any supply by adjusting RS to set lq equal to 1.5 mA." Process 21 was a gold-doped NPN fast switch - 2N2369 is the JEDEC nunber.> I remember reading something about 'electromigration', so chemical changes on the chip due to applied voltages.So atoms do do move around in, or on the surface of the chip, under some circumstances. It doesn't seem to have been a problem in this application <snip> -- Bill Sloman, Sydney
BJT E-B zener
Started by ●February 28, 2023
Reply by ●March 1, 20232023-03-01
Reply by ●March 1, 20232023-03-01
On Wednesday, March 1, 2023 at 1:51:01 AM UTC-4, Jan Panteltje wrote:> On a sunny day (Tue, 28 Feb 2023 08:45:28 -0800) it happened John Larkin > <jla...@highlandSNIPMEtechnology.com> wrote in > <gpbsvhl4gjtjc4ra4...@4ax.com>: > >On Tue, 28 Feb 2023 16:33:40 GMT, Jan Panteltje <al...@comet.invalid> > >wrote: > > > >>On a sunny day (Tue, 28 Feb 2023 08:00:50 -0800) it happened John Larkin > >><jla...@highlandSNIPMEtechnology.com> wrote in > >><j89svh5rd7a465i52...@4ax.com>: > >> > >>>On Tue, 28 Feb 2023 15:48:10 GMT, Jan Panteltje <al...@comet.invalid> > >>>wrote: > >>> > >>>>On a sunny day (Tue, 28 Feb 2023 07:05:54 -0800 (PST)) it happened > >>>>"neo5...@gmail.com" <neo5...@gmail.com> wrote in > >>>><2728e43f-ea4f-4df3...@googlegroups.com>: > >>>> > >>>>>Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage > >>>>>than > >>>>>a regular zener but I dont know what kind of power it can handle or how stable it is when used this way. > >>>> > >>>>If you connect the collector to the base as well, > >>>>the thing can take more current > >>>> > >>>> > >>>> - > >>>> > >>>>Now 200 mA Imax collector current counts, zenering about .7 V gives .7 * .2 = .140 mW > >>>>Note that Vbe sat may be as high as .95 V at 90 mA Ic, even higher at > >>>>Also Vbe is very temperature dependent. > >>>>See datasheet. > >>>>If you want a precise voltage better use something else. > >>>> > >>>>A big Si diode used in forward direction will give the same effect, voltage drop and temperature problems. > >>> > >>>But that's not a zener. > >> > >> > >>Ah, seems he wants it reverse biased, my error. > >>Using the thing that way may cause it to die after a while :-) > > > >It would be an interesting experiment to measure the b-e zener voltage > >long-term, at a couple of currents. Beta degrades in a transistor if > >the base is zenered, so something is going on. > I remember reading something about 'ectromigration', so chemical changes on the chip > due to applied voltages.Electromigration is not a chemical change. It is literally the movement of metal atoms in traces on the board, due to the high current densities. No chemical changes, just moving stuff around. -- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Reply by ●March 2, 20232023-03-02
On a sunny day (Wed, 1 Mar 2023 07:29:32 -0800 (PST)) it happened Ricky <gnuarm.deletethisbit@gmail.com> wrote in <0cf8844d-d732-4990-af66-13740960714cn@googlegroups.com>:>>On Wednesday, March 1, 2023 at 1:51:01=E2=80=AFAM UTC-4, Jan Panteltje wrote: >>I remember reading something about 'ectromigration', so chemical changes on >>the chip due to applied voltages.>Electromigration is not a chemical change. It is literally the movement of >metal atoms in traces on the board, due to the high current densities. No >chemical changes, just moving stuff around.OK, thanks
Reply by ●March 2, 20232023-03-02
On 2023-03-01 10:29, Ricky wrote:> On Wednesday, March 1, 2023 at 1:51:01 AM UTC-4, Jan Panteltje > wrote: >> On a sunny day (Tue, 28 Feb 2023 08:45:28 -0800) it happened John >> Larkin <jla...@highlandSNIPMEtechnology.com> wrote in >> <gpbsvhl4gjtjc4ra4...@4ax.com>: >>> On Tue, 28 Feb 2023 16:33:40 GMT, Jan Panteltje >>> <al...@comet.invalid> wrote: >>> >>>> On a sunny day (Tue, 28 Feb 2023 08:00:50 -0800) it happened >>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote in >>>> <j89svh5rd7a465i52...@4ax.com>: >>>> >>>>> On Tue, 28 Feb 2023 15:48:10 GMT, Jan Panteltje >>>>> <al...@comet.invalid> wrote: >>>>> >>>>>> On a sunny day (Tue, 28 Feb 2023 07:05:54 -0800 (PST)) it >>>>>> happened "neo5...@gmail.com" <neo5...@gmail.com> wrote in >>>>>> <2728e43f-ea4f-4df3...@googlegroups.com>: >>>>>> >>>>>>> Where would I go to look for information about using the >>>>>>> E-B connection of a 2N3904 as a zener? It has much better >>>>>>> leakage than a regular zener but I dont know what kind of >>>>>>> power it can handle or how stable it is when used this >>>>>>> way. >>>>>> >>>>>> If you connect the collector to the base as well, the thing >>>>>> can take more current >>>>>> >>>>>> >>>>>> - >>>>>> >>>>>> Now 200 mA Imax collector current counts, zenering about .7 >>>>>> V gives .7 * .2 = .140 mW Note that Vbe sat may be as high >>>>>> as .95 V at 90 mA Ic, even higher at Also Vbe is very >>>>>> temperature dependent. See datasheet. If you want a precise >>>>>> voltage better use something else. >>>>>> >>>>>> A big Si diode used in forward direction will give the same >>>>>> effect, voltage drop and temperature problems. >>>>> >>>>> But that's not a zener. >>>> >>>> >>>> Ah, seems he wants it reverse biased, my error. Using the thing >>>> that way may cause it to die after a while :-) >>> >>> It would be an interesting experiment to measure the b-e zener >>> voltage long-term, at a couple of currents. Beta degrades in a >>> transistor if the base is zenered, so something is going on. >> I remember reading something about 'ectromigration', so chemical >> changes on the chip due to applied voltages. > Electromigration is not a chemical change. It is literally the > movement of metal atoms in traces on the board, due to the high > current densities. No chemical changes, just moving stuff around. > Electromigration is more of an on-chip issue. The usual rule is that current density in top-level copper metal (the least resistant to EM failure) should be kept below 1e6 A/cm**2. Lower levels are constrained by the surrounding dielectric, which (provided that it's fully dense) gives some restoring force to resist the metal's bunching up. Re: Avalanche Avalanche can cause hot-carrier damage if it isn't part of the design. Sufficiently-energetic carriers can knock atoms out of place, causing interstitials and propagating dislocations. These form recombination sites, leading to the decline in the BJT beta. Interstitials can be annealed easily--there are stories of Bob Widlar mashing his cigar onto a metal-cased transistor to 'repair' avalanche data. Remarkable guy, Widlar, but as attached to his own legend as Patton--not as bad as MacArthur. (But then, who is?) ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●March 2, 20232023-03-02
On Tuesday, February 28, 2023 at 7:05:59 AM UTC-8, neo5...@gmail.com wrote:> Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way.The 'much better leakage' relates to test protocols, more than reality. The recommendation to use a 2N3904 as a reference goes back to National Semiconductor's (now TI) process for making those; the Motorola (now ONsemi) process might be different (and breakdown is only specified as 'over 6.0V'). E-B breakdown also applies the opposite to 'normal' field on the surface of the transistor, where the B and E contacts are made; such surfaces are passivated, but field reversal can move dirt on the surface to age the component abnormally. So, no one knows 'how stable it is' for this usage, unless they've time/temperature tested a few batches from a known process and the manufacturer doesn't change anything. That '2N3904' part number was defined many decades ago, there have been lots of variant parts holding to that loose specification, sold under that part number. It'll probably work. That doesn't mean it's good design practice to depend on it.
Reply by ●March 2, 20232023-03-02
On Friday, March 3, 2023 at 1:27:43 AM UTC+11, Phil Hobbs wrote:> On 2023-03-01 10:29, Ricky wrote:> On Wednesday, March 1, 2023 at > 1:51:01 AM UTC-4, Jan Panteltje > > wrote: > >> On a sunny day (Tue, 28 Feb 2023 08:45:28 -0800) it happened John > >> Larkin <jla...@highlandSNIPMEtechnology.com> wrote in > >> <gpbsvhl4gjtjc4ra4...@4ax.com>: > >>> On Tue, 28 Feb 2023 16:33:40 GMT, Jan Panteltje > >>> <al...@comet.invalid> wrote: > >>> > >>>> On a sunny day (Tue, 28 Feb 2023 08:00:50 -0800) it happened > >>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote in > >>>> <j89svh5rd7a465i52...@4ax.com>: > >>>> > >>>>> On Tue, 28 Feb 2023 15:48:10 GMT, Jan Panteltje > >>>>> <al...@comet.invalid> wrote: > >>>>> > >>>>>> On a sunny day (Tue, 28 Feb 2023 07:05:54 -0800 (PST)) it > >>>>>> happened "neo5...@gmail.com" <neo5...@gmail.com> wrote in > >>>>>> <2728e43f-ea4f-4df3...@googlegroups.com>: > >>>>>> > >>>>>>> Where would I go to look for information about using the > >>>>>>> E-B connection of a 2N3904 as a zener? It has much better > >>>>>>> leakage than a regular zener but I dont know what kind of > >>>>>>> power it can handle or how stable it is when used this > >>>>>>> way. > >>>>>> > >>>>>> If you connect the collector to the base as well, the thing > >>>>>> can take more current > >>>>>> > >>>>>> > >>>>>> - > >>>>>> > >>>>>> Now 200 mA Imax collector current counts, zenering about .7 > >>>>>> V gives .7 * .2 = .140 mW Note that Vbe sat may be as high > >>>>>> as .95 V at 90 mA Ic, even higher at Also Vbe is very > >>>>>> temperature dependent. See datasheet. If you want a precise > >>>>>> voltage better use something else. > >>>>>> > >>>>>> A big Si diode used in forward direction will give the same > >>>>>> effect, voltage drop and temperature problems. > >>>>> > >>>>> But that's not a zener. > >>>> > >>>> > >>>> Ah, seems he wants it reverse biased, my error. Using the thing > >>>> that way may cause it to die after a while :-) > >>> > >>> It would be an interesting experiment to measure the b-e zener > >>> voltage long-term, at a couple of currents. Beta degrades in a > >>> transistor if the base is zenered, so something is going on. > >> I remember reading something about 'ectromigration', so chemical > >> changes on the chip due to applied voltages. > > Electromigration is not a chemical change. It is literally the > > movement of metal atoms in traces on the board, due to the high > > current densities. No chemical changes, just moving stuff around. > > > Electromigration is more of an on-chip issue. The usual rule is that > current density in top-level copper metal (the least resistant to EM > failure) should be kept below 1e6 A/cm**2. Lower levels are constrained > by the surrounding dielectric, which (provided that it's fully dense) > gives some restoring force to resist the metal's bunching up. > > Re: Avalanche > > Avalanche can cause hot-carrier damage if it isn't part of the design. > > Sufficiently-energetic carriers can knock atoms out of place, causing > interstitials and propagating dislocations. These form recombination > sites, leading to the decline in the BJT beta. Interstitials can be > annealed easily--there are stories of Bob Widlar mashing his cigar onto > a metal-cased transistor to 'repair' avalanche data.The version I heard was HP technicians stubbing out their cigarette on failing output transistors.> Remarkable guy, Widlar, but as attached to his own legend as Patton--not as bad as MacArthur. (But then, who is?) ;)Widlar didn't actually take himself all that seriously (unlike Patton), and he designed some wonderful integrated circuits. Avalanche discharge takes place in remarkably tiny areas - and generates light so you can see where it is happening. Using the base-emitter junction in a 2N2369 as a zener/avalanche diode - the junction breaks down at a voltage where both mechanism are active - seems unlikely to makes any changes to the junction that will change the breakdown voltage. It's been a known trick for some fifty years now, and nobody has reported any such shift. -- Bill Sloman, Sydney
Reply by ●March 2, 20232023-03-02
On Friday, March 3, 2023 at 4:07:47 AM UTC+11, whit3rd wrote:> On Tuesday, February 28, 2023 at 7:05:59 AM UTC-8, neo5...@gmail.com wrote: > > Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way. > The 'much better leakage' relates to test protocols, more than reality. The recommendation to > use a 2N3904 as a reference goes back to National Semiconductor's (now TI) process for making those; > the Motorola (now ONsemi) process might be different (and breakdown is only specified as 'over 6.0V').National Application note AN-74 https://www.ti.com/lit/an/snoa654a/snoa654a.pdf?ts=1677789876245&ref_url=https%253A%252F%252Fwww.google.com%252F specifies the National Semiconductor process 21 transistor 2N2369. The 2N3904 is process 23, which is much the same but on a slightly bigger chip with more interdigitation. Both are gold-doped.> E-B breakdown also applies the opposite to 'normal' field on the surface of the > transistor, where the B and E contacts are made; such surfaces are passivated, but > field reversal can move dirt on the surface to age the component abnormally. > > So, no one knows 'how stable it is' for this usage, unless they've time/temperature > tested a few batches from a known process and the manufacturer doesn't change anything. > That '2N3904' part number was defined many decades ago, there have been lots > of variant parts holding to that loose specification, sold under that part number. > > It'll probably work. That doesn't mean it's good design practice to depend on it.Probably not, but the trick has been known for fifty years now. If it eventually fails we'd probably have heard of it. -- Bill Sloman, Sydney
Reply by ●March 2, 20232023-03-02
On Thu, 2 Mar 2023 09:07:43 -0800 (PST), whit3rd <whit3rd@gmail.com> wrote:>On Tuesday, February 28, 2023 at 7:05:59?AM UTC-8, neo5...@gmail.com wrote: >> Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way. > >The 'much better leakage' relates to test protocols, more than reality. The recommendation to >use a 2N3904 as a reference goes back to National Semiconductor's (now TI) process for making those; >the Motorola (now ONsemi) process might be different (and breakdown is only specified as 'over 6.0V'). > >E-B breakdown also applies the opposite to 'normal' field on the surface of the >transistor, where the B and E contacts are made; such surfaces are passivated, but >field reversal can move dirt on the surface to age the component abnormally. > >So, no one knows 'how stable it is' for this usage, unless they've time/temperature >tested a few batches from a known process and the manufacturer doesn't change anything. >That '2N3904' part number was defined many decades ago, there have been lots >of variant parts holding to that loose specification, sold under that part number. > >It'll probably work. That doesn't mean it's good design practice to depend on it.You can get a 0.5% bandgap voltage reference for 4 cents.
Reply by ●March 2, 20232023-03-02
On Friday, March 3, 2023 at 8:06:17 AM UTC+11, John Larkin wrote:> On Thu, 2 Mar 2023 09:07:43 -0800 (PST), whit3rd <whi...@gmail.com> > wrote: > >On Tuesday, February 28, 2023 at 7:05:59?AM UTC-8, neo5...@gmail.com wrote: > >> Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way. > > > >The 'much better leakage' relates to test protocols, more than reality. The recommendation to > >use a 2N3904 as a reference goes back to National Semiconductor's (now TI) process for making those; > >the Motorola (now ONsemi) process might be different (and breakdown is only specified as 'over 6.0V'). > > > >E-B breakdown also applies the opposite to 'normal' field on the surface of the > >transistor, where the B and E contacts are made; such surfaces are passivated, but > >field reversal can move dirt on the surface to age the component abnormally. > > > >So, no one knows 'how stable it is' for this usage, unless they've time/temperature > >tested a few batches from a known process and the manufacturer doesn't change anything. > >That '2N3904' part number was defined many decades ago, there have been lots > >of variant parts holding to that loose specification, sold under that part number. > > > >It'll probably work. That doesn't mean it's good design practice to depend on it. > > You can get a 0.5% bandgap voltage reference for 4 cents.But John Larkin doesn't know the part number. H's probably thinking of the LM4040 https://www.ti.com/lit/ds/symlink/lm4040-n.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1677716796343&ref_url=https%253A%252F%252Fwww.mouser.jp%252F but that is lot more expensive than 4 cents - $1.37 even in thousands. -- Bill Sloman, Sydney
Reply by ●March 3, 20232023-03-03
On 02-03-2023 22:33, Anthony William Sloman wrote:> On Friday, March 3, 2023 at 8:06:17 AM UTC+11, John Larkin wrote: >> On Thu, 2 Mar 2023 09:07:43 -0800 (PST), whit3rd <whi...@gmail.com> >> wrote: >>> On Tuesday, February 28, 2023 at 7:05:59?AM UTC-8, neo5...@gmail.com wrote: >>>> Where would I go to look for information about using the E-B connection of a 2N3904 as a zener? It has much better leakage than a regular zener but I dont know what kind of power it can handle or how stable it is when used this way. >>> >>> The 'much better leakage' relates to test protocols, more than reality. The recommendation to >>> use a 2N3904 as a reference goes back to National Semiconductor's (now TI) process for making those; >>> the Motorola (now ONsemi) process might be different (and breakdown is only specified as 'over 6.0V'). >>> >>> E-B breakdown also applies the opposite to 'normal' field on the surface of the >>> transistor, where the B and E contacts are made; such surfaces are passivated, but >>> field reversal can move dirt on the surface to age the component abnormally. >>> >>> So, no one knows 'how stable it is' for this usage, unless they've time/temperature >>> tested a few batches from a known process and the manufacturer doesn't change anything. >>> That '2N3904' part number was defined many decades ago, there have been lots >>> of variant parts holding to that loose specification, sold under that part number. >>> >>> It'll probably work. That doesn't mean it's good design practice to depend on it. >> >> You can get a 0.5% bandgap voltage reference for 4 cents. > > But John Larkin doesn't know the part number. H's probably thinking of the LM4040 > > https://www.ti.com/lit/ds/symlink/lm4040-n.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1677716796343&ref_url=https%253A%252F%252Fwww.mouser.jp%252F > > but that is lot more expensive than 4 cents - $1.37 even in thousands. >6 cents: https://www.avnet.com/shop/us/products/diodes-inc/az431lantr-e1-3074457345625002718?CMP=EMA_FindChips_inventoryfeed_VSE
