current limiter chip...

jlarkin@highlandsniptechnology.com wrote:
On Sat, 3 Sep 2022 14:21:40 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

John Larkin wrote:
On Fri, 2 Sep 2022 17:01:45 -0400 (EDT), Martin Rid
martin_riddle@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid<martin_riddle@verison.net> wrote:>John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r>> I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?>>Mp5032>USB current limiter/switch>>Cheers3 amps would fry the thing I want to protect.

The curve for Rlimit goes down to 500ma.

\"Set the current limit level. Place a resistor between ILIM and GND to
achieve a high accuracy current limit. The current limit threshold
varies versus the output voltage to maintain a fairly constant output
power limit.\"

Sounds tricky. And maybe it needs to do a handshake with a USB device.



Is it less than 500ma?

Cheers

The current (no pun) problem is to protect a pulse output stage that
makes 5 volts out, from a 5 volt supply. It normally has a 50 ohm
series resistor from the driver to the connector, but some customers
want us to be able to programmably short that resistor so they get 5
volts - not 2.5 - into their 50 ohm load.

That current limit should be a bit above 100 mA. But the current limit
problem keeps coming up.


Hmm. My usual approach is to put a resistor in the supply lead, with a
nice beefy bypass cap to let the output amp ride over transients. That
won\'t work unless you can power the output amp from a bit taller supply.

When there\'s at least a bit of headroom available, and the current limit
can be a bit sloppy, I\'ve also used a low-sat PNP transistor with a
resistor to ground from the base. This keeps the PNP in saturation in
normal use, and rides over brief transients, even pretty large ones.
Longer transients deplete the stored charge in the base, so the
collector voltage collapses in a few microseconds.

(I realize you\'re looking for a specific integrated solution to a
precise problem, but (a) I know of none, and (b) general on-topic
discussion is always good.)

Cheers

Phil Hobbs

The part I want seems pretty obvious, but nobody seems to make it.

Somebody, National maybe, once sold a PNP transistor with a super
tight beta spec, specifically as a current limiter. But it wouldn\'t
thermal limit.

One alternate is an LM317 type reg with a big resistor from +12 volts
to limit current. That\'s klunky.
Click to expand...

Well, Martin R\'s ncv47722 device looks interesting.

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
 
On Friday, September 2, 2022 at 4:20:49 PM UTC-7, John Larkin wrote:

The current (no pun) problem is to protect a pulse output stage that
makes 5 volts out, from a 5 volt supply. It normally has a 50 ohm
series resistor from the driver to the connector, but some customers
want us to be able to programmably short that resistor so they get 5
volts - not 2.5 - into their 50 ohm load.

That current limit should be a bit above 100 mA.
Click to expand...

For that, a plain old 78L05 regulator will conduct, but limit at about 200 mA.
That\'s \'a bit above\'; in SOT89 package, TS78L05ACY limits at 100 mA, nominal.

I think you\'re right about PWM in the BCR430 part; the datasheet resistor description
makes it clearly NOT a series sense resistor for the current. I saw the pass transistor,
resistor programming, and error amplifier, and drew my conclusion too soon.
 
On Sat, 3 Sep 2022 14:15:58 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Friday, September 2, 2022 at 4:20:49 PM UTC-7, John Larkin wrote:

The current (no pun) problem is to protect a pulse output stage that
makes 5 volts out, from a 5 volt supply. It normally has a 50 ohm
series resistor from the driver to the connector, but some customers
want us to be able to programmably short that resistor so they get 5
volts - not 2.5 - into their 50 ohm load.

That current limit should be a bit above 100 mA.

For that, a plain old 78L05 regulator will conduct, but limit at about 200 mA.
That\'s \'a bit above\'; in SOT89 package, TS78L05ACY limits at 100 mA, nominal.

I think you\'re right about PWM in the BCR430 part; the datasheet resistor description
makes it clearly NOT a series sense resistor for the current. I saw the pass transistor,
resistor programming, and error amplifier, and drew my conclusion too soon.
Click to expand...

The data sheet is pitiful. As is common these days.
 
On Fri, 2 Sep 2022 15:13:22 -0700 (PDT), Ed Lee
<edward.ming.lee@gmail.com> wrote:

On Friday, September 2, 2022 at 1:58:09 PM UTC-7, John Larkin wrote:
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?

Mp5032
USB current limiter/switch

Cheers
3 amps would fry the thing I want to protect.

What I/O voltage?
Click to expand...

Ideally 5 volts in and out.

We could make a limiter with a shunt resistor, an opamp, and a p-fet,
and some passives; it wouldn\'t thermal limit so we\'d have to work
around that. We prefer something with fewer parts.

We do have a digital solution for this case, but I\'d generally like to
find a current limiter part.
 
lørdag den 3. september 2022 kl. 23.51.15 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 2 Sep 2022 15:13:22 -0700 (PDT), Ed Lee
edward....@gmail.com> wrote:

On Friday, September 2, 2022 at 1:58:09 PM UTC-7, John Larkin wrote:
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?

Mp5032
USB current limiter/switch

Cheers
3 amps would fry the thing I want to protect.

What I/O voltage?
Ideally 5 volts in and out.

We could make a limiter with a shunt resistor, an opamp, and a p-fet,
and some passives; it wouldn\'t thermal limit so we\'d have to work
around that. We prefer something with fewer parts.

We do have a digital solution for this case, but I\'d generally like to
find a current limiter part.
Click to expand...

USB power switch like RT9728A ?
 
On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?
Click to expand...

You might try Torex for the app.

eg XC6193 is a pretty fancy rail switch/controller.

XC6299/6212 are controllable LDOs with enable, inrush
and thermal limits, in smaller sot23-6 type bodies.

RL
 
On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?
Click to expand...

Thanks for the suggestions.


Diodes AP22652

Richtek RT9728A, RT9722

TI TPS25221

ON NCP380

seem to be basically identical current limiter chips. This family has
fixed and adjustable current limit parts, and both continuous and
on/off versions.

Microchip Mic2091 and MP5036 and MIC20x9 look close.
 
tirsdag den 6. september 2022 kl. 17.37.58 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?
Thanks for the suggestions.


Diodes AP22652

Richtek RT9728A, RT9722

TI TPS25221

ON NCP380

seem to be basically identical current limiter chips. This family has
fixed and adjustable current limit parts, and both continuous and
on/off versions.

Microchip Mic2091 and MP5036 and MIC20x9 look close.
Click to expand...

here\'s a few more

https://lcsc.com/product-detail/Power-Distribution-Switches_XI-AN-Aerosemi-Tech-MT9700_C89855.html
https://lcsc.com/product-detail/Power-Distribution-Switches_LOWPOWER-LPW5209AB5F_C387727.html
https://lcsc.com/product-detail/Power-Distribution-Switches_MICRONE-Nanjing-Micro-One-Elec-ME1502AM5G_C2911283.html
 
On Tue, 6 Sep 2022 09:36:33 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

tirsdag den 6. september 2022 kl. 17.37.58 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?
Thanks for the suggestions.


Diodes AP22652

Richtek RT9728A, RT9722

TI TPS25221

ON NCP380

seem to be basically identical current limiter chips. This family has
fixed and adjustable current limit parts, and both continuous and
on/off versions.

Microchip Mic2091 and MP5036 and MIC20x9 look close.

here\'s a few more

https://lcsc.com/product-detail/Power-Distribution-Switches_XI-AN-Aerosemi-Tech-MT9700_C89855.html
https://lcsc.com/product-detail/Power-Distribution-Switches_LOWPOWER-LPW5209AB5F_C387727.html
https://lcsc.com/product-detail/Power-Distribution-Switches_MICRONE-Nanjing-Micro-One-Elec-ME1502AM5G_C2911283.html
Click to expand...

Cool.

Most of these parts bottom out at about 400 mA on their graphs, but
they might limit at little lower in real life. I\'d prefer maybe 200
mA, but it needn\'t be a precise limit, so we could test some and see
if they look OK.
 
On Sun, 4 Sep 2022 01:19:17 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

lørdag den 3. september 2022 kl. 23.51.15 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 2 Sep 2022 15:13:22 -0700 (PDT), Ed Lee
edward....@gmail.com> wrote:

On Friday, September 2, 2022 at 1:58:09 PM UTC-7, John Larkin wrote:
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?

Mp5032
USB current limiter/switch

Cheers
3 amps would fry the thing I want to protect.

What I/O voltage?
Ideally 5 volts in and out.

We could make a limiter with a shunt resistor, an opamp, and a p-fet,
and some passives; it wouldn\'t thermal limit so we\'d have to work
around that. We prefer something with fewer parts.

We do have a digital solution for this case, but I\'d generally like to
find a current limiter part.

USB power switch like RT9728A ?
Click to expand...

Looks nice, 32 cents by the reel, probably 2nd sourced, but doesn\'t
seem to be available.
 
søndag den 4. september 2022 kl. 19.33.48 UTC+2 skrev jla...@highlandsniptechnology.com:
On Sun, 4 Sep 2022 01:19:17 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:

lørdag den 3. september 2022 kl. 23.51.15 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 2 Sep 2022 15:13:22 -0700 (PDT), Ed Lee
edward....@gmail.com> wrote:

On Friday, September 2, 2022 at 1:58:09 PM UTC-7, John Larkin wrote:
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?

Mp5032
USB current limiter/switch

Cheers
3 amps would fry the thing I want to protect.

What I/O voltage?
Ideally 5 volts in and out.

We could make a limiter with a shunt resistor, an opamp, and a p-fet,
and some passives; it wouldn\'t thermal limit so we\'d have to work
around that. We prefer something with fewer parts.

We do have a digital solution for this case, but I\'d generally like to
find a current limiter part.

USB power switch like RT9728A ?
Looks nice, 32 cents by the reel, probably 2nd sourced, but doesn\'t
seem to be available.
Click to expand...

maybe one of these then?
https://www.digikey.com/en/products/detail/diodes-incorporated/AP22653AW6-7/12728454
https://www.digikey.com/en/products/detail/diodes-incorporated/AP22652AW6-7/12728380
 
On Sun, 4 Sep 2022 11:42:29 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

søndag den 4. september 2022 kl. 19.33.48 UTC+2 skrev jla...@highlandsniptechnology.com:
On Sun, 4 Sep 2022 01:19:17 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:

lørdag den 3. september 2022 kl. 23.51.15 UTC+2 skrev jla...@highlandsniptechnology.com:
On Fri, 2 Sep 2022 15:13:22 -0700 (PDT), Ed Lee
edward....@gmail.com> wrote:

On Friday, September 2, 2022 at 1:58:09 PM UTC-7, John Larkin wrote:
On Fri, 2 Sep 2022 16:12:09 -0400 (EDT), Martin Rid
martin...@verison.net> wrote:

John Larkin <jlarkin@highland_atwork_technology.com> Wrote in message:r
I want a small current limiter chip.Sot-23 sizeLow voltage dropoutCurrent and thermal limitedResistor programmable limitReasonable priceAvailable!Does anybody know of one?

Mp5032
USB current limiter/switch

Cheers
3 amps would fry the thing I want to protect.

What I/O voltage?
Ideally 5 volts in and out.

We could make a limiter with a shunt resistor, an opamp, and a p-fet,
and some passives; it wouldn\'t thermal limit so we\'d have to work
around that. We prefer something with fewer parts.

We do have a digital solution for this case, but I\'d generally like to
find a current limiter part.

USB power switch like RT9728A ?
Looks nice, 32 cents by the reel, probably 2nd sourced, but doesn\'t
seem to be available.

maybe one of these then?
https://www.digikey.com/en/products/detail/diodes-incorporated/AP22653AW6-7/12728454
https://www.digikey.com/en/products/detail/diodes-incorporated/AP22652AW6-7/12728380
Click to expand...

There is a TI part with the same pinout and similar specs. Three
sources maybe.
 
You need an old voltage regulator chip with shutdown. In Dil14. There
are chips which go up or down at certain temperature.
Or 78L05 with very high input voltage
On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?
Click to expand...
 
On Tue, 06 Sep 2022 08:37:47 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Fri, 02 Sep 2022 10:44:42 -0700, John Larkin
jlarkin@highland_atwork_technology.com> wrote:

I want a small current limiter chip.

Sot-23 size
Low voltage dropout
Current and thermal limited
Resistor programmable limit
Reasonable price
Available!

Does anybody know of one?

Thanks for the suggestions.


Diodes AP22652

Richtek RT9728A, RT9722

TI TPS25221

ON NCP380

seem to be basically identical current limiter chips. This family has
fixed and adjustable current limit parts, and both continuous and
on/off versions.

Microchip Mic2091 and MP5036 and MIC20x9 look close.
Click to expand...

Check pin compatibility . . .

RL
 
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