high-side current sensor...

S

server

Guest
We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.



--

I yam what I yam - Popeye
 
S

server

Guest
On Mon, 10 Jan 2022 19:26:09 -0800, jlarkin@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

INA280 looks pretty good.



--

I yam what I yam - Popeye
 
D

DJ Delorie

Guest
I was going to suggest the INA139 (which I\'ve used) but it only goes to 40v...

INA169 maybe?
 
R

Rick C

Guest
On Monday, January 10, 2022 at 10:39:34 PM UTC-5, DJ Delorie wrote:
I was going to suggest the INA139 (which I\'ve used) but it only goes to 40v...

INA169 maybe?

The LT6106 is an easy to use device, but again, 36 volts only. It only requires a shunt resistor, a series resistor and a final gain setting resistor.. You could design the same circuit yourself as the chip is really just an op amp and a transistor (PNP or PFET). Know any good opamps that work up to 48 volts?

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
W

whit3rd

Guest
On Monday, January 10, 2022 at 7:26:19 PM UTC-8, jla...@highlandsniptechnology.com wrote:
We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents ...

So, is this regulated voltages, nine of \'em, and you want the output currents
from nine low-V regulators, or is it input to the regulators, and is that input somewhere
in the vicinity of 48VDC? Are these nine currents going to include initial
charging of filter capacitors? How big are those capacitors? Are some of the
regulators switchers?

As for \'intelligent cutoffs\', do you want to do that at the high-side? A secondary
low-current power supply grounded at the high rail might be economic, if
you want to have nine sensors and nine cutoffs all near the +48V source.
 
J

Jan Panteltje

Guest
On a sunny day (Mon, 10 Jan 2022 19:26:09 -0800) it happened
jlarkin@highlandsniptechnology.com wrote in
<tltptglt3bo93rfahg44nhdhsfue688iq0@4ax.com>:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

I have some of those Hall modules somewhere
HX03-P 3-50A
and
HX10-P
Manufacturer LEM:
https://www.lem.com/en
works, all I can say
 
P

piglet

Guest
On 11/01/2022 04:26, Rick C wrote:
On Monday, January 10, 2022 at 10:39:34 PM UTC-5, DJ Delorie wrote:
I was going to suggest the INA139 (which I\'ve used) but it only goes to 40v...

INA169 maybe?

The LT6106 is an easy to use device, but again, 36 volts only. It only requires a shunt resistor, a series resistor and a final gain setting resistor. You could design the same circuit yourself as the chip is really just an op amp and a transistor (PNP or PFET). Know any good opamps that work up to 48 volts?

You don\'t need a high voltage opamp - just hang a cheap 5V riro opamp
from the +48V rail with a 5V zener and resistor, the pnp c-b junction
does all the standoff.

60V rated Zetex/Diodes ZXCT1084 is another option.

piglet
 
O

olaf

Guest
jlarkin@highlandsniptechnology.com wrote:


>We can add shunts, or I guess it could be some Hall thing.

MAX4080 ---> 76V

I realy like it....

Olaf
 
S

server

Guest
On Tue, 11 Jan 2022 11:32:13 +0100, olaf <olaf@criseis.ruhr.de> wrote:

jlarkin@highlandsniptechnology.com wrote:


We can add shunts, or I guess it could be some Hall thing.

MAX4080 ---> 76V

I realy like it....

Olaf

Does it work OK? Looks nice, but it violates my Never Buy Maxim rule.
Mouser has stock.

I could maybe do it with 5 or 6 discretes for about 10 cents.



--

I yam what I yam - Popeye
 
C

Clive Arthur

Guest
On 11/01/2022 03:39, DJ Delorie wrote:
I was going to suggest the INA139 (which I\'ve used) but it only goes to 40v...

INA169 maybe?

I\'ve used loads of INA169, they work fine. And they work at
temperatures well past their specified maximum which may be an
indication of their robustness.

--
Cheers
Clive
 
S

Spehro Pefhany

Guest
On Mon, 10 Jan 2022 19:26:09 -0800, jlarkin@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

48V is within range of a bunch of those cheap high monitors.

eg. ZXCT1082/83/84/85/86/87 Diodes Inc. (nee Zetex) but you need a
shunt resistor, of course. AD has some in theory but availability?

There are those Hall sensors, TI, (Allegro?) etc. Availability?

Last time I did this for a flight instrumentation package I used a
RRIO op-amps rated for the supply voltage (OPAxxx) but I don\'t think
there\'s anything easily available safe for 48V direct supply and if
there was it wouldn\'t be cheap x 8.

Maybe use a 5V DC-DC to generate a rail for op-amps @48-5V, use your
most common inexpensive low-Vos RRIO 5V dual or quad op-amps and PNP
transistors or p-channel MOSFETs to transmit the current to near GND.
Should be cheap enough and relatively low parts count.
--
Best regards,
Spehro Pefhany
 
L

Liz Tuddenham

Guest
<jlarkin@highlandsniptechnology.com> wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

Current mirror using pairs of high voltage PNP transistors?


--
~ Liz Tuddenham ~
(Remove the \".invalid\"s and add \".co.uk\" to reply)
www.poppyrecords.co.uk
 
S

server

Guest
On Tue, 11 Jan 2022 10:28:32 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Mon, 10 Jan 2022 19:26:09 -0800, jlarkin@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

48V is within range of a bunch of those cheap high monitors.

eg. ZXCT1082/83/84/85/86/87 Diodes Inc. (nee Zetex) but you need a
shunt resistor, of course. AD has some in theory but availability?

There are those Hall sensors, TI, (Allegro?) etc. Availability?

Last time I did this for a flight instrumentation package I used a
RRIO op-amps rated for the supply voltage (OPAxxx) but I don\'t think
there\'s anything easily available safe for 48V direct supply and if
there was it wouldn\'t be cheap x 8.

Maybe use a 5V DC-DC to generate a rail for op-amps @48-5V, use your
most common inexpensive low-Vos RRIO 5V dual or quad op-amps and PNP
transistors or p-channel MOSFETs to transmit the current to near GND.
Should be cheap enough and relatively low parts count.

This ain\'t bad:

https://www.dropbox.com/s/3b79zaloyf03flv/P940_current_sensor.jpg?raw=1

With 50 or better yet 100 mV across R1, it should be fine. It\'s sure
cheap. R4 performs four distinctly useful functions.

Official current monitor chips seem hard to get lately, and are priced
several times what seems normal.




--

I yam what I yam - Popeye
 
S

server

Guest
On Tue, 11 Jan 2022 16:35:10 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

jlarkin@highlandsniptechnology.com> wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

Current mirror using pairs of high voltage PNP transistors?

I just posted something like that. It should be good enough. If the
voltage drop across Q2 is pitched a little high, so there is a little
positive measurement offset, we can math that out.



--

I yam what I yam - Popeye
 
O

olaf

Guest
jlarkin@highlandsniptechnology.com wrote:


Does it work OK? Looks nice, but it violates my Never Buy Maxim rule.
Mouser has stock.

I dont use it in high production, but in many small circuit to measure
current for prototyping. Work good!

Olaf
 
L

Lasse Langwadt Christensen

Guest
https://lcsc.com/product-detail/span-style-background-color-ff0-Current-span-Sensing-Amplifiers_Diodes-Incorporated-ZXCT1080E5TA_C151589.html
 
S

server

Guest
On Mon, 10 Jan 2022 22:34:08 -0800 (PST), whit3rd <whit3rd@gmail.com>
wrote:

On Monday, January 10, 2022 at 7:26:19 PM UTC-8, jla...@highlandsniptechnology.com wrote:
We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents ...

So, is this regulated voltages, nine of \'em, and you want the output currents
from nine low-V regulators, or is it input to the regulators, and is that input somewhere
in the vicinity of 48VDC? Are these nine currents going to include initial
charging of filter capacitors? How big are those capacitors? Are some of the
regulators switchers?

As for \'intelligent cutoffs\', do you want to do that at the high-side? A secondary
low-current power supply grounded at the high rail might be economic, if
you want to have nine sensors and nine cutoffs all near the +48V source.

There will be eight user-programmable power supplies, each running off
+48, all off a common +48 bus fed from a kilowatt bulk power supply.
Users can potentially install modules and program and load the
supplies such as to cave in the main source, which would be really
ugly. That\'s against the rules in the manual, but we need to protect
things if they do it.

So I want to know all 9 currents, all at 48 volts. Given that info, we
can decide that the main supply is overloaded and shed as many load
boards as needed to keep the main supply happy. And later recover. All
in a sensible documented way. We are debating algorithms for that.

We will have a Zynq fpga/ARM chip, with an integral ADC, so we can
program the FPGA to mux and digitize the currents furiously and leave
the results in 9 registers. Then some FPGA or c-code algorithm can do
the shutdown algorithm.

I\'d expect that we could do it in c code, say 1000 times a second. My
programmers tend to push back against doing fast realtime stuff, but
they will have two 600 MHz ARM cores for Pete\'s sake.





--

I yam what I yam - Popeye
 
S

Spehro Pefhany

Guest
On Tue, 11 Jan 2022 08:36:33 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Tue, 11 Jan 2022 10:28:32 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Mon, 10 Jan 2022 19:26:09 -0800, jlarkin@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

48V is within range of a bunch of those cheap high monitors.

eg. ZXCT1082/83/84/85/86/87 Diodes Inc. (nee Zetex) but you need a
shunt resistor, of course. AD has some in theory but availability?

There are those Hall sensors, TI, (Allegro?) etc. Availability?

Last time I did this for a flight instrumentation package I used a
RRIO op-amps rated for the supply voltage (OPAxxx) but I don\'t think
there\'s anything easily available safe for 48V direct supply and if
there was it wouldn\'t be cheap x 8.

Maybe use a 5V DC-DC to generate a rail for op-amps @48-5V, use your
most common inexpensive low-Vos RRIO 5V dual or quad op-amps and PNP
transistors or p-channel MOSFETs to transmit the current to near GND.
Should be cheap enough and relatively low parts count.


This ain\'t bad:

https://www.dropbox.com/s/3b79zaloyf03flv/P940_current_sensor.jpg?raw=1

With 50 or better yet 100 mV across R1, it should be fine. It\'s sure
cheap. R4 performs four distinctly useful functions.

Nice! Certainly works, and is very simple and cheap. A bit temperature
sensitive (even with matched transistor temperatures).
(~2:1 from 0 to 80°C)? Maybe that\'s good enough for a circuit
breaker type function.

You could use 1/4 of a 10 cent LM324 per channel but it would
complicate the power supply.

Official current monitor chips seem hard to get lately, and are priced
several times what seems normal.

Yes, some are stupidly expensive. And if the customer has designed
them in, they\'ll probably be forced to pay whatever is asked.
--
Best regards,
Spehro Pefhany
 
J

John Larkin

Guest
On Tue, 11 Jan 2022 13:33:32 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 11 Jan 2022 08:36:33 -0800, jlarkin@highlandsniptechnology.com
wrote:

On Tue, 11 Jan 2022 10:28:32 -0500, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Mon, 10 Jan 2022 19:26:09 -0800, jlarkin@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

48V is within range of a bunch of those cheap high monitors.

eg. ZXCT1082/83/84/85/86/87 Diodes Inc. (nee Zetex) but you need a
shunt resistor, of course. AD has some in theory but availability?

There are those Hall sensors, TI, (Allegro?) etc. Availability?

Last time I did this for a flight instrumentation package I used a
RRIO op-amps rated for the supply voltage (OPAxxx) but I don\'t think
there\'s anything easily available safe for 48V direct supply and if
there was it wouldn\'t be cheap x 8.

Maybe use a 5V DC-DC to generate a rail for op-amps @48-5V, use your
most common inexpensive low-Vos RRIO 5V dual or quad op-amps and PNP
transistors or p-channel MOSFETs to transmit the current to near GND.
Should be cheap enough and relatively low parts count.


This ain\'t bad:

https://www.dropbox.com/s/3b79zaloyf03flv/P940_current_sensor.jpg?raw=1

With 50 or better yet 100 mV across R1, it should be fine. It\'s sure
cheap. R4 performs four distinctly useful functions.

Nice! Certainly works, and is very simple and cheap. A bit temperature
sensitive (even with matched transistor temperatures).
(~2:1 from 0 to 80°C)? Maybe that\'s good enough for a circuit
breaker type function.

Tempcos should be OK. One of the functions of R4 is to reduce
self-heating in Q1.

You could use 1/4 of a 10 cent LM324 per channel but it would
complicate the power supply.

Official current monitor chips seem hard to get lately, and are priced
several times what seems normal.

Yes, some are stupidly expensive. And if the customer has designed
them in, they\'ll probably be forced to pay whatever is asked.

There are several basically identical 5-pin current sense chips... all
with different pinouts!

There seem to be lots of >50 volt PNPs for around 2 cents each. We
have stock here on one that cost us - gasp - 8 cents.


--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon
 
S

Simon S Aysdie

Guest
On Tuesday, January 11, 2022 at 8:37:04 AM UTC-8, jla...@highlandsniptechnology.com wrote:
On Tue, 11 Jan 2022 10:28:32 -0500, Spehro Pefhany
spef...@interlogDOTyou.knowwhat> wrote:

On Mon, 10 Jan 2022 19:26:09 -0800, jla...@highlandsniptechnology.com
wrote:

We\'ll have a 48 volt, 20 amp power supply that feeds eight plug-in
modular load boards. We want to measure all 9 currents so that we can
do some sorts of intelligent cutoffs if the eight boards threaten to
cave in the big supply.

So we want nine mediocre-accuracy unipolar high-side current sensors
so we can digitize the currents with a grounded mux/adc.

Does anyone have a favorite but cheap high-side current sense IC?

We can add shunts, or I guess it could be some Hall thing.

48V is within range of a bunch of those cheap high monitors.

eg. ZXCT1082/83/84/85/86/87 Diodes Inc. (nee Zetex) but you need a
shunt resistor, of course. AD has some in theory but availability?

There are those Hall sensors, TI, (Allegro?) etc. Availability?

Last time I did this for a flight instrumentation package I used a
RRIO op-amps rated for the supply voltage (OPAxxx) but I don\'t think
there\'s anything easily available safe for 48V direct supply and if
there was it wouldn\'t be cheap x 8.

Maybe use a 5V DC-DC to generate a rail for op-amps @48-5V, use your
most common inexpensive low-Vos RRIO 5V dual or quad op-amps and PNP
transistors or p-channel MOSFETs to transmit the current to near GND.
Should be cheap enough and relatively low parts count.
This ain\'t bad:

https://www.dropbox.com/s/3b79zaloyf03flv/P940_current_sensor.jpg?raw=1

I\'ve use the above current sense form (more or less) from time to time. My use is typically active bias of class A RF/MMIC amps.

1st time I used it was for biasing a 4W GaAsFET from Celeritek. In fact, Celeritek suggested the basic form. Some polish had to be added. It does temp drift a bit, as already mentioned by Spehro.

With 50 or better yet 100 mV across R1, it should be fine. It\'s sure
cheap. R4 performs four distinctly useful functions.

Official current monitor chips seem hard to get lately, and are priced
several times what seems normal.
--

I yam what I yam - Popeye
 

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