BJT E-B zener...

[Anthony William Sloman]

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

 

[Ricky]

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

 

[Jan Panteltje]

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

 

[Phil Hobbs]

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

 

[whit3rd]

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.

 

[Anthony William Sloman]

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

 

[Anthony William Sloman]

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

 

[John Larkin]

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.

 

[Anthony William Sloman]

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

 

[Klaus Vestergaard Kragelund]

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

 

[Jan Panteltje]

On a sunny day (Fri, 3 Mar 2023 11:01:43 +0100) it happened Klaus Vestergaard
Kragelund <klauskvik@hotmail.com> wrote in <ttsgi6$jssm$1@dont-email.me>:

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

LM317 with adjust to ground is 1.2V bandgap
Or any other voltage you like up to 37 V
https://nl.aliexpress.com/item/32848278588.html
Almost for free
I always have some around.

 

[Anthony William Sloman]

On Friday, March 3, 2023 at 9:52:14 PM UTC+11, Jan Panteltje wrote:

On a sunny day (Fri, 3 Mar 2023 11:01:43 +0100) it happened Klaus Vestergaard
Kragelund <klau...@hotmail.com> wrote in <ttsgi6$jssm$1...@dont-email.me>:
On 02-03-2023 22:33, Anthony William Sloman wrote:
On Friday, March 3, 2023 at 8:06:17â ¯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
LM317 with adjust to ground is 1.2V bandgap
Or any other voltage you like up to 37 V
https://nl.aliexpress.com/item/32848278588.html
Almost for free
I always have some around.

Not exactly precision references, but Jan Panteltje and John Larkin don\'t go in for precision.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Fri, 3 Mar 2023 03:18:22 -0800 (PST)) it happened Anthony
William Sloman <bill.sloman@ieee.org> wrote in
<196fe320-7d36-4056-9574-d0b82078ea59n@googlegroups.com>:

On Friday, March 3, 2023 at 9:52:14=E2=80=AFPM UTC+11, Jan Panteltje wrote:
On a sunny day (Fri, 3 Mar 2023 11:01:43 +0100) it happened Klaus Vestergaard

Kragelund <klau...@hotmail.com> wrote in <ttsgi6$jssm$1...@dont-email.me>:

On 02-03-2023 22:33, Anthony William Sloman wrote:
On Friday, March 3, 2023 at 8:06:17=C3=A2 =C2=AFAM 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=3Ddis-mous-null-mousermode-dsf-pf-null-wwe&ts=3D1677716796343&ref_url=3Dhttps%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=3DEMA_FindChips_inventoryfeed_VSE

LM317 with adjust to ground is 1.2V bandgap
Or any other voltage you like up to 37 V
https://nl.aliexpress.com/item/32848278588.html
Almost for free
I always have some around.

Not exactly precision references, but Jan Panteltje and John Larkin don\'t go
in for precision.

The advantage of LM317 is that you can use a trimpot or resistors to set it quite close to where you want it.
I often use 2 resistors in series, a big one and a smaller one for calibration.
And it can deliver a LOT of current and has proven very reliable over the years
and is still around since 1976
https://en.wikipedia.org/wiki/LM317

 

[Anthony William Sloman]

On Friday, March 3, 2023 at 10:35:48 PM UTC+11, Jan Panteltje wrote:

On a sunny day (Fri, 3 Mar 2023 03:18:22 -0800 (PST)) it happened Anthony
William Sloman <bill....@ieee.org> wrote in
196fe320-7d36-4056...@googlegroups.com>:
On Friday, March 3, 2023 at 9:52:14=E2=80=AFPM UTC+11, Jan Panteltje wrote:
On a sunny day (Fri, 3 Mar 2023 11:01:43 +0100) it happened Klaus Vestergaard

Kragelund <klau...@hotmail.com> wrote in <ttsgi6$jssm$1...@dont-email.me>:

On 02-03-2023 22:33, Anthony William Sloman wrote:
On Friday, March 3, 2023 at 8:06:17=C3=A2 =C2=AFAM 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=3Ddis-mous-null-mousermode-dsf-pf-null-wwe&ts=3D1677716796343&ref_url=3Dhttps%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=3DEMA_FindChips_inventoryfeed_VSE

LM317 with adjust to ground is 1.2V bandgap
Or any other voltage you like up to 37 V
https://nl.aliexpress.com/item/32848278588.html
Almost for free
I always have some around.

Not exactly precision references, but Jan Panteltje and John Larkin don\'t go in for precision.

The advantage of LM317 is that you can use a trimpot or resistors to set it quite close to where you want it.
I often use 2 resistors in series, a big one and a smaller one for calibration.

As if everybody else doesn\'t do the same thing. Putting the calibration resistor in parallel with the main resistor was called \"select on test\" where I worked in England, and was pretty popular. Customers fiddle with trim-pots - we had to put blobs of hot sealing wax on the adjustors so that our service engineers could see if the customers had been fiddling,

And it can deliver a LOT of current and has proven very reliable over the years and is still around since 1976
https://en.wikipedia.org/wiki/LM317

And I designed in a lot of them, but it isn\'t a precise voltage reference, and you really do need a second ground pin to let you set up a Kelvin connection, if you are setting up a serious reference voltage.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Fri, 3 Mar 2023 04:11:31 -0800 (PST)) it happened Anthony
William Sloman <bill.sloman@ieee.org> wrote in
<84e616ac-2578-4e1f-aab3-1d6303f1300fn@googlegroups.com>:

On Friday, March 3, 2023 at 10:35:48=E2=80=AFPM UTC+11, Jan Panteltje wrote:

On a sunny day (Fri, 3 Mar 2023 03:18:22 -0800 (PST)) it happened Anthony

William Sloman <bill....@ieee.org> wrote in
196fe320-7d36-4056...@googlegroups.com>:
On Friday, March 3, 2023 at 9:52:14=3DE2=3D80=3DAFPM UTC+11, Jan Panteltje
wrote:
On a sunny day (Fri, 3 Mar 2023 11:01:43 +0100) it happened Klaus Vestergaard


Kragelund <klau...@hotmail.com> wrote in <ttsgi6$jssm$1...@dont-email.me>:


On 02-03-2023 22:33, Anthony William Sloman wrote:
On Friday, March 3, 2023 at 8:06:17=3DC3=3DA2 =3DC2=3DAFAM 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=3D3Ddis-mous-null-mousermode-dsf-pf-null-wwe&ts=3D3D1677716796343&ref_url=3D3Dhttps%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=3D3DEMA_FindChips_inventoryfeed_VSE


LM317 with adjust to ground is 1.2V bandgap
Or any other voltage you like up to 37 V
https://nl.aliexpress.com/item/32848278588.html
Almost for free
I always have some around.

Not exactly precision references, but Jan Panteltje and John Larkin don\'t
go in for precision.

The advantage of LM317 is that you can use a trimpot or resistors to set it
quite close to where you want it.
I often use 2 resistors in series, a big one and a smaller one for calibration.

As
if everybody else doesn\'t do the same thing. Putting the calibration resistor
in parallel with the main resistor was called \"select on test\" where
I worked in England, and was pretty popular. Customers fiddle with trim-pots
- we had to put blobs of hot sealing wax on the adjustors so that our service
engineers could see if the customers had been fiddling,

And it can deliver a LOT of current and has proven very reliable over the
years and is still around since 1976
https://en.wikipedia.org/wiki/LM317

And I designed in a lot of them, but it isn\'t a precise voltage reference,
and you really do need a second ground pin to let you set up a Kelvin connection,
if you are setting up a serious reference voltage.

I also have some Microchip MCP1525 voltage reference, used it to \'calibrate\' my Chinese multimeters
its +-1%, about 90 cents 100 up, 52 weeks lead time on digikey.

And TL431 pretty stable versus temperature, 100 pieces for 2 Euro 38 on aliexpress.... in stock...

The Microchip PICs I use have a build in 1.024 V voltage reference,,,,
18F14K22 datasheet says: VR01 VFVR Fixed Voltage Reference min 0.984 nom 1.024 max 1.064 V
Good enough for many projects, and comes free with the chip, in stock at severa places, else 24 weeks lead time digikey I think.
Has build in 4 bit DAC multiplier for it, ADCs, hardware comparators.
Many more things exist..

 

[Jan Panteltje]

On Friday, March 3, 2023 at 10:35:48=E2=80=AFPM UTC+11, Jan Panteltje wrote:

The Microchip PICs I use have a build in 1.024 V voltage reference,,,,
18F14K22 datasheet says: VR01 VFVR Fixed Voltage Reference min 0.984 nom 1.024 max 1.064 V
Good enough for many projects, and comes free with the chip, in stock at severa places, else 24 weeks lead time digikey I think.
Has build in 4 bit DAC multiplier for it, ADCs, hardware comparators.
Many more things exist..

PS
when using the Microchip internal reference I usualy let it output
its DAC voltage on a pin for test and measure it
and then use a #define in the ASM for the precise value.
So no trimpots needed to calibrate its ADCs.
; PIC Vref * 4
#define VREF D\'4080\' ; Measured

 

[John Larkin]

On Fri, 03 Mar 2023 16:28:24 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On Friday, March 3, 2023 at 10:35:48=E2=80=AFPM UTC+11, Jan Panteltje wrote:

The Microchip PICs I use have a build in 1.024 V voltage reference,,,,
18F14K22 datasheet says: VR01 VFVR Fixed Voltage Reference min 0.984 nom 1.024 max 1.064 V
Good enough for many projects, and comes free with the chip, in stock at severa places, else 24 weeks lead time digikey I think.
Has build in 4 bit DAC multiplier for it, ADCs, hardware comparators.
Many more things exist..

PS
when using the Microchip internal reference I usualy let it output
its DAC voltage on a pin for test and measure it
and then use a #define in the ASM for the precise value.
So no trimpots needed to calibrate its ADCs.
; PIC Vref * 4
#define VREF D\'4080\' ; Measured

We usually have a BIST analog mux and ADC on a gadget, so we can scan
all the power supplies and temperatures and such. That helps in
production test as well as long-term in the field. The ADC is often
free in a uP or an FPGA.

We usually digitize ground and a good voltage reference as two mux
channels, so we can live calibrate other channels based on those two
points.

We rarely use trimpots. Just for an occasional wideband gain trim,
like in a GHz-class o/e converter or something.

 

[piglet]

On 01/03/2023 14:54, Anthony William Sloman wrote:

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.

Using the C-B diode to temp compensate the E-B breakdown looks
superficially neat but the devil is in the detail - they specify below
unity reverse beta and that is vital. Otherwise once E-B breakdown
occurs transistor action kicks in and you have a negistor or 4-layer
diode kind of effect (imagine an SCR with zener gate to anode),
conceptually like a uniploar low voltage diac. It is a hobbyists trick
low parts count oscillator.

piglet

 

[Phil Hobbs]

On 2023-03-03 15:35, piglet wrote:

On 01/03/2023 14:54, Anthony William Sloman wrote:
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.


Using the C-B diode to temp compensate the E-B breakdown looks
superficially neat but the devil is in the detail - they specify below
unity reverse beta and that is vital. Otherwise once E-B breakdown
occurs transistor action kicks in and you have a negistor or 4-layer
diode kind of effect (imagine an SCR with zener gate to anode),
conceptually like a uniploar low voltage diac. It is a hobbyists trick
low parts count oscillator.

piglet

Fun. I\'ll have to try that with a 2SD2704K (superbeta NPN with a lot of
reverse beta and a spectacularly large BV_EBO).

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

 

[Anthony William Sloman]

On Saturday, March 4, 2023 at 7:36:05 AM UTC+11, piglet wrote:

On 01/03/2023 14:54, Anthony William Sloman wrote:
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.

Using the C-B diode to temp compensate the E-B breakdown looks
superficially neat but the devil is in the detail - they specify below
unity reverse beta and that is vital.

It isn\'t being recommended for every part. The National Semiconductor application note was quite specific about what would work. Others have recommended the 2N3904 part which is process 23, a slight;ly bigger chip with a bit more interdigitation.

Otherwise once E-B breakdown
occurs transistor action kicks in and you have a negistor or 4-layer
diode kind of effect (imagine an SCR with zener gate to anode),
conceptually like a uniploar low voltage diac. It is a hobbyists trick
low parts count oscillator.

You probably couldn\'t see that in LTSpice - all the transistor models are Gummel -Poon which doesn\'t model inverted gain all that accurately.

LTSpice will run the more accurate VBIC model, but the parameters are commercial in confidence, and hobbyists can\'t get at them\'

--
Bill Sloman, Sydney