Using zener diode to protect test circuit?

[Jim Thompson]

On 24 Apr 2005 04:21:05 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

[snip]

It works if you...
Tie input of upper inverter to lower "IN"
Tie input of lower inverter to upper "IN"
Cute! I'll use it ;-)

That's right, thanks! I messed-up when translating my first
drawing to the second one. Here's the corrected schematic.

. _Vdd ----- + out
. / |
. IN ---+--O< |--,
. | \_| | Active bridge rectifier
. unknown \________|_ using cmos hex inverters
. polarity ________| |
. / _ |
. | / | |
. IN ---+--O< |----'
. \_|
. Vss ----- - out

Again, someone must have invented this long ago. Sometime shortly
after the first cmos hex inverters came out in the mid 60s, or at
least soon after cmos became available in low-cost plastic packages
about 35 years ago... But now we can make it with a micro-miniature
ON Semi NL27WZ04 MiniGate™ in a SC70-6 package, a 2.1 x 2.1mm dust
flake. See http://www.onsemi.com/site/content/0,,1241,00.html and
http://www.onsemi.com/pub/Collateral/NL27WZ04-D.PDF

Using the FETs in a low-voltage cmos process allows us to use this
technique down to 1.5V or even less, although of course the FET's
on resistance goes up at low voltages. Has anyone seen an Ron vs
Vdd plot for these low-voltage logic families? ON Semi's NL17SV04
is claimed to work well at 0.9V supply, and deliver 50MHz at 1.2V.

BTW, although the fabulous MiniGate logic sample kit is no longer
available free from ON Semi, it's offered by DigiKey for only $39.
Search on MINIGATEA-KIT. Break out those microscopes!

I simulated it with basically a 74HCU04 structure (UNBUFFERED
Inverter).

That is a SINGLE inverter stage.

I don't know quite what it will do with a 74HC04 (each 'inverter' is
actually 3-stages long).

I'll try that next.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Woodgate]

I read in sci.electronics.design that Jim Thompson
<thegreatone@example.com> wrote (in
<8mbn611gh05v2esnj9u7gg91v5dpor26ir@4ax.com&gt about 'Using zener diode
to protect test circuit?', on Sun, 24 Apr 2005:

That _might_ work if the reverse voltage doesn't ever go above 6V, but
you're playing it awfully close to Absolute Maximum specification.

Are there any NPNs with a higher VEB(BR)? Aren't PNPs better for this
characteristic? A PNP in the 0V is worth an NPN in the +V, surely?
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Jim Thompson]

On Sun, 24 Apr 2005 07:53:28 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On 24 Apr 2005 04:21:05 -0700, Winfield Hill
hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

[snip]

It works if you...
Tie input of upper inverter to lower "IN"
Tie input of lower inverter to upper "IN"
Cute! I'll use it ;-)

That's right, thanks! I messed-up when translating my first
drawing to the second one. Here's the corrected schematic.

. _Vdd ----- + out
. / |
. IN ---+--O< |--,
. | \_| | Active bridge rectifier
. unknown \________|_ using cmos hex inverters
. polarity ________| |
. / _ |
. | / | |
. IN ---+--O< |----'
. \_|
. Vss ----- - out

Again, someone must have invented this long ago. Sometime shortly
after the first cmos hex inverters came out in the mid 60s, or at
least soon after cmos became available in low-cost plastic packages
about 35 years ago... But now we can make it with a micro-miniature
ON Semi NL27WZ04 MiniGate™ in a SC70-6 package, a 2.1 x 2.1mm dust
flake. See http://www.onsemi.com/site/content/0,,1241,00.html and
http://www.onsemi.com/pub/Collateral/NL27WZ04-D.PDF

Using the FETs in a low-voltage cmos process allows us to use this
technique down to 1.5V or even less, although of course the FET's
on resistance goes up at low voltages. Has anyone seen an Ron vs
Vdd plot for these low-voltage logic families? ON Semi's NL17SV04
is claimed to work well at 0.9V supply, and deliver 50MHz at 1.2V.

BTW, although the fabulous MiniGate logic sample kit is no longer
available free from ON Semi, it's offered by DigiKey for only $39.
Search on MINIGATEA-KIT. Break out those microscopes!

I simulated it with basically a 74HCU04 structure (UNBUFFERED
Inverter).

That is a SINGLE inverter stage.

I don't know quite what it will do with a 74HC04 (each 'inverter' is
actually 3-stages long).

I'll try that next.

...Jim Thompson

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability since that is
limited by the rail voltage determining the gate voltage of the main
stage.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Winfield Hill]

Jim Thompson wrote...

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability ...

For this test you'd have to trust your spice FET models near 0V,
which as we've discussed is in the subthreshold zone, where most
models are notoriously faulty. 'U04 parts are popular for linear
amplification, etc, where the spice modeling issue also comes up.
One step in evaluating a model is to measure the transfer function
of some real n- and p-channel parts, which either Paul or I will
do for some ON Semi low-voltage unbuffered MiniGate inverters in
the next few days. It's a continuation of what I started with
the 2n7000 and some other JFETs and power mosfets.


--
Thanks,
- Win

 

[Jim Thompson]

On 24 Apr 2005 08:28:59 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability ...

For this test you'd have to trust your spice FET models near 0V,
which as we've discussed is in the subthreshold zone, where most
models are notoriously faulty. 'U04 parts are popular for linear
amplification, etc, where the spice modeling issue also comes up.
One step in evaluating a model is to measure the transfer function
of some real n- and p-channel parts, which either Paul or I will
do for some ON Semi low-voltage unbuffered MiniGate inverters in
the next few days. It's a continuation of what I started with
the 2n7000 and some other JFETs and power mosfets.

I modeled this with X-FAB CMOS (integrated circuit) models which DO
model sub-threshold.

I know that they work... I'm in a hearing aid project where virtually
everything is operated sub-threshold. And also VERY noisy :-(

I'm using PSpice Level=7 / HSpice Level=49, none of this Level=3 shit
for me... they only do modeling that crufty for discretes.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On 24 Apr 2005 08:28:59 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability ...

For this test you'd have to trust your spice FET models near 0V,
which as we've discussed is in the subthreshold zone, where most
models are notoriously faulty. 'U04 parts are popular for linear
amplification, etc, where the spice modeling issue also comes up.
One step in evaluating a model is to measure the transfer function
of some real n- and p-channel parts, which either Paul or I will
do for some ON Semi low-voltage unbuffered MiniGate inverters in
the next few days. It's a continuation of what I started with
the 2n7000 and some other JFETs and power mosfets.

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Active bridge rectifier using cmos hex inverters (from S.E.D)
- WinsRectifierHCU04.pdf
Message-ID: <mdln61pss09je5a9t792uoahn72tqt5rqu@4ax.com>

I forgot that, in May 1997, I had redesigned ON-Semi's unbuffered
inverter (...U04) to fit their change to Chartered Semiconductor's
foundry.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Winfield Hill]

Jim Thompson wrote...

Winfield Hill wrote:
Jim Thompson wrote...

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability ...

For this test you'd have to trust your spice FET models near 0V,
which as we've discussed is in the subthreshold zone, where most
models are notoriously faulty. 'U04 parts are popular for linear
amplification, etc, where the spice modeling issue also comes up.
One step in evaluating a model is to measure the transfer function
of some real n- and p-channel parts, which either Paul or I will
do for some ON Semi low-voltage unbuffered MiniGate inverters in
the next few days. It's a continuation of what I started with
the 2n7000 and some other JFETs and power mosfets.

I modeled this with X-FAB CMOS (integrated circuit) models which
DO model sub-threshold.

I know that they work... I'm in a hearing aid project where virtually
everything is operated sub-threshold. And also VERY noisy :-(

I'm using PSpice Level=7 / HSpice Level=49, none of this Level=3
shit for me... they only do modeling that crufty for discretes.

This is good, and I envy you your model, but it should still
somehow be verified as correct for the parts we're able to buy.


--
Thanks,
- Win

 

On Sun, 24 Apr 2005 07:39:19 -0700, Jim Thompson
<thegreatone@example.com> wrote:

That _might_ work if the reverse voltage doesn't ever go above 6V, but
you're playing it awfully close to Absolute Maximum specification.

Maybe put a diode in the base lead to gain an extra 0.7 volts of

protection. Since it's a 5V input, that might just be enough to make
it perfectly safe.

Stepan

 

[John Woodgate]

I read in sci.electronics.design that Jim Thompson
<thegreatone@example.com> wrote (in
<fmgn61dcomrmmbi19iuu6r216cvr12kg9h@4ax.com&gt about 'Active bridge
rectifier using cmos hex inverters, was Using zener diode to protect
test circuit?', on Sun, 24 Apr 2005:

WARNING!!!! Norton AV found W32.Beagle.AG@mm virus in this message and
has removed it. Virus scanning of outgoing messages is in force here.

On 24 Apr 2005 08:28:59 -0700, Winfield Hill
hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Interesting result is that the 74HC04 isn't as good as the simple
74HCU04 near zero, and has no better load capability ...

For this test you'd have to trust your spice FET models near 0V,
which as we've discussed is in the subthreshold zone, where most
models are notoriously faulty. 'U04 parts are popular for linear
amplification, etc, where the spice modeling issue also comes up.
One step in evaluating a model is to measure the transfer function
of some real n- and p-channel parts, which either Paul or I will
do for some ON Semi low-voltage unbuffered MiniGate inverters in
the next few days. It's a continuation of what I started with
the 2n7000 and some other JFETs and power mosfets.

I modeled this with X-FAB CMOS (integrated circuit) models which DO
model sub-threshold.

I know that they work... I'm in a hearing aid project where virtually
everything is operated sub-threshold. And also VERY noisy :-(

I'm using PSpice Level=7 / HSpice Level=49, none of this Level=3 shit
for me... they only do modeling that crufty for discretes.

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Jim Thompson]

On Sun, 24 Apr 2005 19:09:05 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Jim Thompson
thegreatone@example.com> wrote (in
fmgn61dcomrmmbi19iuu6r216cvr12kg9h@4ax.com&gt about 'Active bridge
rectifier using cmos hex inverters, was Using zener diode to protect
test circuit?', on Sun, 24 Apr 2005:

WARNING!!!! Norton AV found W32.Beagle.AG@mm virus in this message and
has removed it. Virus scanning of outgoing messages is in force here.


[snip]

What version of NAV are you using?

If it was really there it got there from something in your machine or
news server.

I run the latest version of NAV, and am a paid subscriber to the
automatic (almost daily) updates.

I just scanned the original here and it shows no problems.

I also scanned a downloaded copy to see if a virus was somehow
inserted.... neeeeerp!

I also run SpyBot, ScanSpyware and AdAware at least once a week; plus
I have a hardware firewall, so I think I have a clean machine ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Sun, 24 Apr 2005 19:09:05 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Jim Thompson
thegreatone@example.com> wrote (in
fmgn61dcomrmmbi19iuu6r216cvr12kg9h@4ax.com&gt about 'Active bridge
rectifier using cmos hex inverters, was Using zener diode to protect
test circuit?', on Sun, 24 Apr 2005:

WARNING!!!! Norton AV found W32.Beagle.AG@mm virus in this message and
has removed it. Virus scanning of outgoing messages is in force here.

[snip]

John, I just realized that you referenced a text message. Where's the
virus ?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Sun, 24 Apr 2005 17:49:31 GMT, snovotill@hotmail.com wrote:

On Sun, 24 Apr 2005 07:39:19 -0700, Jim Thompson
thegreatone@example.com> wrote:


That _might_ work if the reverse voltage doesn't ever go above 6V, but
you're playing it awfully close to Absolute Maximum specification.

Maybe put a diode in the base lead to gain an extra 0.7 volts of
protection. Since it's a 5V input, that might just be enough to make
it perfectly safe.

Stepan

Naaah! You'd still have BVCEOrev back thru from the load

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Winfield Hill]

Jim Thompson wrote...

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Active bridge rectifier using cmos hex inverters
(from S.E.D)- WinsRectifierHCU04.pdf
Message-ID: <mdln61pss09je5a9t792uoahn72tqt5rqu@4ax.com

I forgot that, in May 1997, I had redesigned ON-Semi's unbuffered
inverter (...U04) to fit their change to Chartered Semiconductor's
foundry.

That's very nice, can you show us the spice-model code?


--
Thanks,
- Win

 

[Jim Thompson]

On 24 Apr 2005 12:10:34 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Active bridge rectifier using cmos hex inverters
(from S.E.D)- WinsRectifierHCU04.pdf
Message-ID: <mdln61pss09je5a9t792uoahn72tqt5rqu@4ax.com

I forgot that, in May 1997, I had redesigned ON-Semi's unbuffered
inverter (...U04) to fit their change to Chartered Semiconductor's
foundry.

That's very nice, can you show us the spice-model code?

Sure. It's been 8 years, so it's out of NDA...

Subject: Re: Active bridge rectifier using cmos hex inverters (from
S.E.D) - WinsRectifierHCU04.pdf - CharterModels.zip
Message-ID: <3gtn6199ccqhfh7hpf7sg9jlosv9jqbk0p@4ax.com>
References: <mdln61pss09je5a9t792uoahn72tqt5rqu@4ax.com>

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

On Sun, 24 Apr 2005 11:51:27 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Naaah! You'd still have BVCEOrev back thru from the load

Would a few hundred nanofarads worth of decoupling caps in the load

matter though? I know that certain things like LEDs can be damaged by
very low reverse currents due to localized heating in the die, due to
non-uniform reverse breakdown over the entire junction, but is that
the case for transistor be junction?

stepan

 

On Sun, 24 Apr 2005 20:29:20 GMT, snovotill@hotmail.com wrote:

On Sun, 24 Apr 2005 11:51:27 -0700, Jim Thompson
thegreatone@example.com> wrote:

Naaah! You'd still have BVCEOrev back thru from the load

Would a few hundred nanofarads worth of decoupling caps in the load
matter though? I know that certain things like LEDs can be damaged by
very low reverse currents due to localized heating in the die, due to
non-uniform reverse breakdown over the entire junction, but is that
the case for transistor be junction?

I should have mentioned that there aught not be much charge left on

the decoupling caps by the time you disconnect and re-connect the
circuit. So I wonder how much abuse an EB junction can take. Yes, I
don't think anyone would want to see an electrolytic in there.

Stepan

 

[Aubrey McIntosh, Ph.D.]

Jim Thompson wrote:

On Sat, 23 Apr 2005 15:56:05 +0100, "Andrew" <ajhuk@hotmail.com
wrote:




The way the big boys do it can be seen at

http://www.analog-innovations.com/SED/OverAndReverseVoltageProtection.pdf

I have used similar schemes in LiIon battery charger integrated
circuits, to prevent over-charging OR over-discharging.

...Jim Thompson

Why not use a zener instead of R1, R2, DZ1? The only thing I noticed
when simulating with LTSPICE was the power dissipation at R3 at 5V.

 

[Jonathan Westhues]

"Aubrey McIntosh, Ph.D." <newsposter@spam.vima.austin.tx.us> wrote in
message news:116qmgpp7l3hc0a@corp.supernews.com...

Why not use a zener instead of R1, R2, DZ1? The only thing I noticed
when simulating with LTSPICE was the power dissipation at R3 at 5V.

How would you connect it? If I understand correctly then DZ1 is not being
used as a shunt regulator. As soon as the voltage at the connection of R2
and R3 goes above Vref, the TL431 turns on all the way and Q1 snaps on. The
TL431 is either all the way on or all the way off, never in between.

That means that the overvoltage trigger point is insensitive to the Vbe of
Q1. It also means that M2 will be either on all the way or off all the way,
instead of turning off slowly as Vin goes above the limit.

Jonathan
http://cq.cx/

 

[Jim Thompson]

On Mon, 25 Apr 2005 17:31:45 -0400, "Jonathan Westhues"
<please-see-website@nospam.com> wrote:

"Aubrey McIntosh, Ph.D." <newsposter@spam.vima.austin.tx.us> wrote in
message news:116qmgpp7l3hc0a@corp.supernews.com...
Why not use a zener instead of R1, R2, DZ1? The only thing I noticed
when simulating with LTSPICE was the power dissipation at R3 at 5V.

How would you connect it? If I understand correctly then DZ1 is not being
used as a shunt regulator. As soon as the voltage at the connection of R2
and R3 goes above Vref, the TL431 turns on all the way and Q1 snaps on. The
TL431 is either all the way on or all the way off, never in between.

That means that the overvoltage trigger point is insensitive to the Vbe of
Q1. It also means that M2 will be either on all the way or off all the way,
instead of turning off slowly as Vin goes above the limit.

Jonathan
http://cq.cx/

See Aubrey, Jonathan understands.

So much for the value of a PhD ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Aubrey McIntosh, Ph.D.]

Jim Thompson wrote:

On Mon, 25 Apr 2005 17:31:45 -0400, "Jonathan Westhues"
please-see-website@nospam.com> wrote:


"Aubrey McIntosh, Ph.D." <newsposter@spam.vima.austin.tx.us> wrote in
message news:116qmgpp7l3hc0a@corp.supernews.com...

Why not use a zener instead of R1, R2, DZ1? The only thing I noticed
when simulating with LTSPICE was the power dissipation at R3 at 5V.

How would you connect it? If I understand correctly then DZ1 is not being
used as a shunt regulator. As soon as the voltage at the connection of R2
and R3 goes above Vref, the TL431 turns on all the way and Q1 snaps on. The
TL431 is either all the way on or all the way off, never in between.

That means that the overvoltage trigger point is insensitive to the Vbe of
Q1. It also means that M2 will be either on all the way or off all the way,
instead of turning off slowly as Vin goes above the limit.

Jonathan
http://cq.cx/



See Aubrey, Jonathan understands.

So much for the value of a PhD ;-)

...Jim Thompson

Yeah. I remember our discussion on low voltage zeners from last year
now. I agree with you, but I'll forget again.

Jonathan explains better too. I suspect the Engineer -- Scientist gap
dominates the EE -- Chemist gap on this one.

I started with a zener because I didn't know what the TL431 even was
this morning, and didn't have a model, and I wanted to poke around in
other parts of the circuit. Not good engineering, but fine for a rainy
morning's pasttime.

I placed http://aubrey.vima.austin.tx.us/crowbar.zip online. This zip
file has an LTSPICE model for the TL431 in it. Perhaps more
interestingly are the two pdf files, one for the circuit similar to
Jim's, and one with the pesky zener. The discrepancies in part numbers
are because I used what was at hand in LTSPICE.

What I noticed is the increase in power dissipated by the control
circuit at about 5.29 - 5.34V for the zener, against lower power
dissipation overall. I don't know if the model that I grabbed off the
net gives realistic power dissipation in the TL431 or not.

Now I'm off to play with Win's hex inverter circuit. I actually may
have parts for that, left over from the Goder booster.