24V to 500-1000V, 20W floating DC-DC converter...

[legg]

On Wed, 09 Sep 2020 11:08:49 -0700, John Larkin

<snip>

Actually, with the PNP, it doesn\'t need a b-e resistor. Once, about 60
years ago, people used leaky germanium transistors, so using b-e
resistors became folklore.

It\'s still advisable for any npn running over it\'s Vce
range at the temperature limit.

Why?

Because.

I should have said ANY bipolar transistor, used in
a power circuit. Leakage current is process controlled
and pretty stable; that is to say - it is generally
untested.

Iceo is usually worse than Icbo, because it is generated
by concurrent Icbo/beta effects. The emitter-base resistor
avoids the effect on Icbo, by permitting a path for Icb
that is not amplified - as I understand it.

As with all silicon device leakage, it gets worse non-
linearly, with temperature. In doing so - it adds to
self heating which will aggravate a supposedly static
condition. Local hot-spots on a wafer can develop.

Most nondestructive Ice/Vce plots will show this effect
as a \'negative resistance\' slope at lower currents.
This reduces between the stimulated conditions as
Icbo becomes Icbx - from no bias to reverse bias -
as will occur if some unaccounted for current is
forced through an emitter-base resistor that is missing
or inappropriately large.

If this were a thyristor structure . . .

Under transient conditions, the emitter-base resistor
also aids in reducing miller charge effects, through
the same mechanism, though saturation effects would
dominate in a non-linear switching circuit.

As the OP is anticipating a battery protection circuit,
leakage current may only be a concern if connections
remain, on the shelf.

In a simple circuits like the OP\'s, where the TL431
can\'t be guaranteed \'off\' above 1Vak, a path for it\'s
stray current, to bypass the bipolar\'s base terminal, is
only prudent.

RL

 

[legg]

On Wed, 9 Sep 2020 11:12:19 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

<snip>

You\'d normally want to keep the TL431 in linear operation.
Minimum spec is Ik >= 1mA for bog standard TL431. There\'s
no spec for Ik, out of regulation.

Maximum Ik at 11V is about 30mA, before you\'d get overheating.

It will be much less than 11V for the TL431. I think it can handle 100mA.

The emitter resistor is an ideal place to swot excess power
in both the bipolar transistor and the TL431.

RL

 

[Jasen Betts]

On 2020-09-09, Edward Lee <edward.ming.lee@gmail.com> wrote:

I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?

TL431 wants about 1mA to function correctly, (*1)

So something less than 600 ohms, eg 470 or 560 to allow the transotor
to switch off.

At half a watt dissipation in the TL431 (*2), max current at 12V is about 40mA,
so you need a beta of over 120 in the transistor, which is getting
expensive at 5A, so use a Sziklai pair.
(Darlington would work too, but NPNs are generally preferable to PNPs)

Consider using a power resistor (2 ohms, 60W) on the collector side of the
transistor (*3), that way you can use a smaller heatsink. (you only need to
dissipate about 15W now (*4))

There\'s probably a way to use more resistors and transistors and
dissipate even less heat in silicon

1: \"RECOMMENDED OPERATING CONDITIONS\" bottom of page 2
2: \"MAXIMUM RATINGS\" page 2
3: collector as drawn in the schematic, this would be the
emitter lead of the large NPN in the sziklai pair.
4: peak heating of the transistor is at about 2.5A

--
Jasen.

 

[Jasen Betts]

On 2020-09-09, Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:

onsdag den 9. september 2020 kl. 20.17.40 UTC+2 skrev Edward Lee:
On Wednesday, September 9, 2020 at 11:08:08 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 10:26:14 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Wednesday, September 9, 2020 at 10:14:34 AM UTC-7, John Larkin wrote:
On Wed, 9 Sep 2020 08:42:20 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Wednesday, September 9, 2020 at 7:28:15 AM UTC-7, John Larkin wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
You could fry the TL431 at 5 amps out, from too much PNP base current.

5A max for the AWG22 wires. Actual current may be couple of As for an instant.

A p-channel mosfet would help there, instead of the PNP.

OK.

But the answer could be 5K either way.

OK, thanks.
Actually, with the PNP, it doesn\'t need a b-e resistor. Once, about 60
years ago, people used leaky germanium transistors, so using b-e
resistors became folklore.

OK, i\'ll try a 5 ohm emitter resistor to limit the current. Once triggered, it will probably start to discharge into other cells, but that\'s fine.
Check your battery spec. A float voltage will seldom be 12V.

Maximum is 12.6V for lithium battery.

You\'re looking for a series cell ballancing circuit . . ?

Yes. each 12V module (3x 4.2V) has it\'s own BMS ballancing circuit. I just need to limit external voltage to 12V. 4 modules for 48V. 8 modules for 96V.

sure you need the 12V limit? wouldn\'t it already be limited by the individual BMSs?

when the BMS goes open-circuit to protect the battery you still need
a way to continue to charge the other batteries in the series string.

--
Jasen.

 

[legg]

On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?

Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

RL

 

[Edward Lee]

On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:

On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.

 

[Edward Lee]

On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:

On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.

The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

 

[Edward Lee]

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:

On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group.. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.

 

[legg]

On Sat, 12 Sep 2020 12:08:29 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip


Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.

Run the simulation; balance is windowed naturally, so balanced
consumption is a few uA.

Comparators and hysterisis are for nincompoops. Present company
excluded.

RL

 

[Jasen Betts]

On 2020-09-12, Edward Lee <edward.ming.lee@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.

+------------------+------+
| | |
BAT1 | 1M
12V | |
| | |
+--------+-[22]-balancer--+
| | | |
BAT2 .--(---------\' 1M
12V | `---------. |
| | | |
+-----+--+-[22]-balancer--+
| | | |
BAT3 .--(---------\' 1M
12V | `---------. |
| | | |
+-----+----[22]-balancer--+
| | |
BAT4 | 1M
12V | |
| | |
+------------------+------+

each balancer (which is basically an op-amp driiving a
complementary emitter follower) only sees about 24V
but yeah 1mA to run an LM358 could hurt.
but your TL431 circuit uses about the same amount of power.

a low power op-amp like TBS611 at 100uA is about 10 times better
but at $1.33 about 10 times the price

--
Jasen.

 

[Edward Lee]

each balancer (which is basically an op-amp driiving a
complementary emitter follower) only sees about 24V
but yeah 1mA to run an LM358 could hurt.
but your TL431 circuit uses about the same amount of power.

TL431 only needed during charging. Would be nice to use balancer during discharging.

a low power op-amp like TBS611 at 100uA is about 10 times better
but at $1.33 about 10 times the price

Can\'t find that part. Who makes it?

 

[legg]

On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.

Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL

 

[Edward Lee]

On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:

On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL.

OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.

 

[legg]

On Sat, 12 Sep 2020 18:43:18 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL.

OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.

This circuit is developed from conventional rail splitter
balancing circuits by me in the refurb of a set of Owon
oscilloscope batteries on my bench - these were not balanced
as supplied, where failing cells produced early loss of
capacity.

The natural deadband is a \'defect\' of any linear voltage
follower, and is used to advantage here.

The circuit, as published and maintained on VE3UTE service,
is in the public domain. Note that the .plt file will not
plot in LTspice installations that do not support unicode
text. The OP amp used there has an Iq ~50uA, similar to
TSX631 parts actually used in my battery refurbs.

You will need to breadboard and test any circuit that you
use in this or similar applications. Familiarity with the
effect of gain, offsets, tolerances and noise should be
examined. Ground plane layout is advisable.

All measurements attempted on high-z nodes require care
to take loading effects into account - best to avoid them
where possible - there are plenty of low-z nodes or ~0V
branches that are less succeptible to measurement error.
It\'s slow DC, but scope it anyways to avoid surprises.

Note that some of the ICs listeded are reverse polarity
protected up to ~18V by their spec sheet. In applications
where cells may be removed or inserted in a string, or
where fault interruptors may function, the single-fault
abnormal conditions must be examined carefully.

A battery is always live and ready to screw you around.
R5 is there for a reason - silicon shorts on a battery are
no fun.

RL

 

[Edward Lee]

On Saturday, September 12, 2020 at 7:55:21 PM UTC-7, legg wrote:

On Sat, 12 Sep 2020 18:43:18 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL.

OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.
This circuit is developed from conventional rail splitter
balancing circuits by me in the refurb of a set of Owon
oscilloscope batteries on my bench - these were not balanced
as supplied, where failing cells produced early loss of
capacity.

The natural deadband is a \'defect\' of any linear voltage
follower, and is used to advantage here.

The circuit, as published and maintained on VE3UTE service,
is in the public domain. Note that the .plt file will not
plot in LTspice installations that do not support unicode
text. The OP amp used there has an Iq ~50uA, similar to
TSX631 parts actually used in my battery refurbs.

You will need to breadboard and test any circuit that you
use in this or similar applications. Familiarity with the
effect of gain, offsets, tolerances and noise should be
examined. Ground plane layout is advisable.

All measurements attempted on high-z nodes require care
to take loading effects into account - best to avoid them
where possible - there are plenty of low-z nodes or ~0V
branches that are less succeptible to measurement error.
It\'s slow DC, but scope it anyways to avoid surprises.

Note that some of the ICs listeded are reverse polarity
protected up to ~18V by their spec sheet. In applications
where cells may be removed or inserted in a string, or
where fault interruptors may function, the single-fault
abnormal conditions must be examined carefully.

A battery is always live and ready to screw you around.
R5 is there for a reason - silicon shorts on a battery are
no fun.

RL

OK, thanks. I\'ll quote you for credit. My version is almost identical, except for the opamp feedback. I just use open loop for now.

You don\'t have to warn me about batteries. I already burn my fingers and BMS boards many time doing prototype.

 

[Jasen Betts]

On 2020-09-12, Edward Lee <edward.ming.lee@gmail.com> wrote:

each balancer (which is basically an op-amp driiving a
complementary emitter follower) only sees about 24V
but yeah 1mA to run an LM358 could hurt.
but your TL431 circuit uses about the same amount of power.

TL431 only needed during charging. Would be nice to use balancer during discharging.


a low power op-amp like TBS611 at 100uA is about 10 times better
but at $1.33 about 10 times the price

Can\'t find that part. Who makes it?

I typed \"low power op amp\" into google, and got a link to the ST micro site.
https://www.st.com/en/amplifiers-and-comparators/low-power-op-amps-lt1-ma.html
clicked on a link in the grid it took me here

https://www.st.com/content/st_com/en/products/amplifiers-and-comparators/operational-amplifiers-op-amps/precision-op-amps-lt50-mhz/high-voltage-op-amps-from-10-v-to-new-36-v-series/tsb611.html

Seems they could benefit from some SEO.

--
Jasen.

 

[legg]

On Sat, 12 Sep 2020 20:05:52 -0700 (PDT), Edward Lee
<edward.ming.lee@gmail.com> wrote:

On Saturday, September 12, 2020 at 7:55:21 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 18:43:18 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL.

OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.
This circuit is developed from conventional rail splitter
balancing circuits by me in the refurb of a set of Owon
oscilloscope batteries on my bench - these were not balanced
as supplied, where failing cells produced early loss of
capacity.

The natural deadband is a \'defect\' of any linear voltage
follower, and is used to advantage here.

The circuit, as published and maintained on VE3UTE service,
is in the public domain. Note that the .plt file will not
plot in LTspice installations that do not support unicode
text. The OP amp used there has an Iq ~50uA, similar to
TSX631 parts actually used in my battery refurbs.

You will need to breadboard and test any circuit that you
use in this or similar applications. Familiarity with the
effect of gain, offsets, tolerances and noise should be
examined. Ground plane layout is advisable.

All measurements attempted on high-z nodes require care
to take loading effects into account - best to avoid them
where possible - there are plenty of low-z nodes or ~0V
branches that are less succeptible to measurement error.
It\'s slow DC, but scope it anyways to avoid surprises.

Note that some of the ICs listeded are reverse polarity
protected up to ~18V by their spec sheet. In applications
where cells may be removed or inserted in a string, or
where fault interruptors may function, the single-fault
abnormal conditions must be examined carefully.

A battery is always live and ready to screw you around.
R5 is there for a reason - silicon shorts on a battery are
no fun.

RL

OK, thanks. I\'ll quote you for credit. My version is almost identical, except for the opamp feedback. I just use open loop for now.

You don\'t have to warn me about batteries. I already burn my fingers and BMS boards many time doing prototype.

Open loop won\'t give you a uA drain window, around
the balance condition..

RL

 

[Edward Lee]

On Sunday, September 13, 2020 at 6:15:55 AM UTC-7, legg wrote:

On Sat, 12 Sep 2020 20:05:52 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 7:55:21 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 18:43:18 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 4:56:26 PM UTC-7, legg wrote:
On Sat, 12 Sep 2020 12:24:28 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:

On Saturday, September 12, 2020 at 12:12:44 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 12:08:35 PM UTC-7, Edward Lee wrote:
On Saturday, September 12, 2020 at 11:58:14 AM UTC-7, legg wrote:
On Wed, 9 Sep 2020 05:21:42 -0700 (PDT), Edward Lee
edward....@gmail.com> wrote:
I can\'t figure out how to post new message with the new google group. A search of TL431 came up with this thread recently. So, i am high-jacking this for a quick question:

For isolated application, the feedback divider has to be secondary side only
and a TL431 used for error amp, into an opto, in the usual way.

I need a 12V 5A High Current Shunt Regulator, using fig. 19 of page 7

https://www.onsemi.com/pub/Collateral/TL431-D.PDF

I am using 10K for R1, 1.1K for R2. What should i use for Rbe of the pass transistor (TO-220 PNP)?
Seeing as how you\'re using this circuit for balancing (which it
doesn\'t actually do - it\'s just overcharge limiting), you might
be interested in the \'non-digital\', \'non-comparator\' balance
method used here -

http://ve3ute.ca/query/balance_analog_001.zip

Yes, that\'s pretty close to the balancing part of my batteries.. However, the constantly on buffers/drivers drain out the batteries. I am in fact trying to figure out how to window out the middle part. When the batteries are fairly balanced, i want to turn off the buffers/drivers.
The shunt regulators are in addition to the BMS balancers. Both circuits are necessary.

Also, the LT1782 only goes up to 18V. I am using LM358 on 24V, and up to 36V.
Op amp is your choice.

LT6000
LT6001
LT1672
LT1494
AD8657
AD8659
LT6023

These have Iq of as low as 1.6uA, and run on voltages
as high as 36V.

The balance circuit, itself, is never meant to see
2 x cell voltages.

Run the simulation.

RL.

OK, thanks. The LT17s and LT60s sound good, but a bit pricey. Is the circuit your own design, or pull from somewhere? Just wondering if there is pattern or copyright issue for production.
This circuit is developed from conventional rail splitter
balancing circuits by me in the refurb of a set of Owon
oscilloscope batteries on my bench - these were not balanced
as supplied, where failing cells produced early loss of
capacity.

The natural deadband is a \'defect\' of any linear voltage
follower, and is used to advantage here.

The circuit, as published and maintained on VE3UTE service,
is in the public domain. Note that the .plt file will not
plot in LTspice installations that do not support unicode
text. The OP amp used there has an Iq ~50uA, similar to
TSX631 parts actually used in my battery refurbs.

You will need to breadboard and test any circuit that you
use in this or similar applications. Familiarity with the
effect of gain, offsets, tolerances and noise should be
examined. Ground plane layout is advisable.

All measurements attempted on high-z nodes require care
to take loading effects into account - best to avoid them
where possible - there are plenty of low-z nodes or ~0V
branches that are less succeptible to measurement error.
It\'s slow DC, but scope it anyways to avoid surprises.

Note that some of the ICs listeded are reverse polarity
protected up to ~18V by their spec sheet. In applications
where cells may be removed or inserted in a string, or
where fault interruptors may function, the single-fault
abnormal conditions must be examined carefully.

A battery is always live and ready to screw you around.
R5 is there for a reason - silicon shorts on a battery are
no fun.

RL

OK, thanks. I\'ll quote you for credit. My version is almost identical, except for the opamp feedback. I just use open loop for now.

You don\'t have to warn me about batteries. I already burn my fingers and BMS boards many time doing prototype.
Open loop won\'t give you a uA drain window, around
the balance condition..

RL

Yes, this and the heavy duty lm358 is killing my batteries. I owe you the \"legg resistor\".