C
Clive Arthur
Guest
On 30/09/2022 21:14, John Larkin wrote:
12V LDO regulator with thermal shutdown.
--
Cheers
Clive
12V LDO regulator with thermal shutdown.
--
Cheers
Clive
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Mike Monett VE3BTI
Guest
Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
Very nice catch. It works. Thanks.
--
MRM
look closer at the schematic, the reverse protection does work
the first FET is reverse so initially the body diode will work as a
series diode and when the FET turns on so there is no voltage drop
Very nice catch. It works. Thanks.
--
MRM
M
Mike Monett VE3BTI
Guest
Mike Monett VE3BTI <spamme@not.com> wrote:
TL431OVP updated to show change and give credit. Thanks.
https://tinyurl.com/z8d5secn
--
MRM
Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
look closer at the schematic, the reverse protection does work
the first FET is reverse so initially the body diode will work as a
series diode and when the FET turns on so there is no voltage drop
Very nice catch. It works. Thanks.
TL431OVP updated to show change and give credit. Thanks.
https://tinyurl.com/z8d5secn
--
MRM
J
John Larkin
Guest
On Sat, 1 Oct 2022 22:49:05 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:
It can be done wrong.
Soft gate drive can be a hazard.
Zener+triac could allow a couple of volts of negative swing.
Except that said stupid person will ship it back for us to fix.
<pallison49@gmail.com> wrote:
Sylvia Else wrote:
=============
Crowbar circuit?
** See JL\'s first post, forth para.
Yes.
I like crowbars. No finesse required.
It can be done wrong.
** A 16amp triac with a 12v zener provides full protection.
Soft gate drive can be a hazard.
Zener+triac could allow a couple of volts of negative swing.
Will trip at 13V with normal polarity and about 1.5V reverse.
Anyone stupid enough to use the wrong voltage/ polarity wall wart deserves to see it die.
..... Phil
Except that said stupid person will ship it back for us to fix.
J
John Larkin
Guest
On Sun, 02 Oct 2022 05:03:55 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:
2576 switches at 50 KHz with nice soft edges. It needs an external
schottky so there\'s no shoot-through current spike.
<pNaonStpealmtje@yahoo.com> wrote:
On a sunny day (Sat, 01 Oct 2022 12:23:27 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
qk4hjhtnek9nievrbc26g6g2oip5mbpal0@4ax.com>:
The ideal product handles up to +-48 at zero source impedance and
behaves gracefully for any combination of brownouts and
fumble-fingers.
From datasheet quote:
LM2576/LM2576HV Series
SIMPLE SWITCHER ® 3A Step-Down Voltage Regulator
General Description Features
The LM2576 series of regulators are monolithic integrated n 3.3V, 5V, 12V, 15V, and adjustable output versions
circuits that provide all the active functions for a step-down n Adjustable version output voltage range,
(buck) switching regulator, capable of driving 3A load with 1.23V to 37V (57V for HV version) ± 4% max over
excellent line and load regulation. These devices are avail- line and load conditions
able in fixed output voltages of 3.3V, 5V, 12V, 15V, and an n Guaranteed 3A output current
adjustable output version. n Wide input voltage range, 40V up to 60V for
Requiring a minimum number of external components, these HV version
So HV version, preceded by bridge rectifier and insulated wart input.
Used this chip, did not see ultra short spikes
but I have no femtosecond capable scope...
10 to 12 GHz sat reception was still OK though.
2576 switches at 50 KHz with nice soft edges. It needs an external
schottky so there\'s no shoot-through current spike.
J
John Larkin
Guest
On Sun, 2 Oct 2022 14:04:15 +1100, Sylvia Else <sylvia@email.invalid>
wrote:
A polyfuse doesn\'t need a fuse holder and doesn\'t need to be replaced.
There\'s no room in our small boxes for an external-access type fuse
holder anyhow.
If the wart current limits before the poly opens up, that\'s OK. Warts
do current limit. Some DC, some burp mode.
But some customers run our stuff off a big DC bus with maybe a 20 amp
breaker somewhere.
wrote:
On 02-Oct-22 3:33 am, John Larkin wrote:
On Sat, 1 Oct 2022 19:28:19 +1000, Sylvia Else <sylvia@email.invalid
wrote:
On 01-Oct-22 6:14 am, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
Crowbar circuit?
Sylvia.
That would work, with a polyfuse and a big diode for reverse voltage.
I can get a dpak SCR that will handle 50 amps for a while.
Just a zener to the gate of an SCR is probably OK for modest
short-circuit currents. Big crowbars need a fast gate driver, diac or
something.
I thought the usual go was to short circuit the current long enough to
blow a conventional fuse. Of course, you have to handle the case where
the PS cannot supply enough current to blow the fuse, but sits there and
fizzles instead.
Or is even fuse replacement beyond the customer\'s competence? Would you
need to confiscate everything conductive and fuse sized first?
Sylvia.
A polyfuse doesn\'t need a fuse holder and doesn\'t need to be replaced.
There\'s no room in our small boxes for an external-access type fuse
holder anyhow.
If the wart current limits before the poly opens up, that\'s OK. Warts
do current limit. Some DC, some burp mode.
But some customers run our stuff off a big DC bus with maybe a 20 amp
breaker somewhere.
J
John Larkin
Guest
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
<clive@nowaytoday.co.uk> wrote:
That would work if the LDO can stand +24v input. It still needs
reverse protection.
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
I suspect that negative-center warts are rare these days.
My next problem is a bulletproof UVLO and switcher sequencing.
<clive@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
I suspect that negative-center warts are rare these days.
My next problem is a bulletproof UVLO and switcher sequencing.
L
Lasse Langwadt Christensen
Guest
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
if it is always from an isolated wallwart, a bridge rectifier?
LM5164 ?
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
J
John Larkin
Guest
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
Maybe not available.
We have LM2576HV in stock, and the regular, non-HV (40 volts max)
version seems to be available. Slow and quiet. So I\'ll probably go
polyfuse, negative clamp diode, LM2576 to +7 and work down from there.
TI makes a zillion versions of their adorable little 6-pin synchronous
switchers and some are available in reel quantity. I won\'t name my
pick until we have a reel or two on the way.
https://www.dropbox.com/s/jban5vjybbb2g77/TPS54302_PWM.JPG?raw=1
https://www.dropbox.com/s/6prmxq1i2k4gutq/TPS54302_rise.JPG?raw=1
https://www.dropbox.com/s/etctkh2rzesockj/TPS54302_spectrum.JPG?raw=1
https://www.dropbox.com/s/qfzl1azmn67q9wk/TPS54302_sanded.jpg?raw=1
TPS54302 is good for 28v in but is hard to get. There are tons of the
17v parts around.
<langwadt@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
We have LM2576HV in stock, and the regular, non-HV (40 volts max)
version seems to be available. Slow and quiet. So I\'ll probably go
polyfuse, negative clamp diode, LM2576 to +7 and work down from there.
TI makes a zillion versions of their adorable little 6-pin synchronous
switchers and some are available in reel quantity. I won\'t name my
pick until we have a reel or two on the way.
https://www.dropbox.com/s/jban5vjybbb2g77/TPS54302_PWM.JPG?raw=1
https://www.dropbox.com/s/6prmxq1i2k4gutq/TPS54302_rise.JPG?raw=1
https://www.dropbox.com/s/etctkh2rzesockj/TPS54302_spectrum.JPG?raw=1
https://www.dropbox.com/s/qfzl1azmn67q9wk/TPS54302_sanded.jpg?raw=1
TPS54302 is good for 28v in but is hard to get. There are tons of the
17v parts around.
L
Lasse Langwadt Christensen
Guest
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS..
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
J
John Larkin
Guest
On Sun, 2 Oct 2022 10:02:43 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
We don\'t buy \"asian brands.\"
We have LM2576 in stock and in our PCB library, and it\'s available
from authorized distributors.
<langwadt@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
We don\'t buy \"asian brands.\"
We have LM2576 in stock and in our PCB library, and it\'s available
from authorized distributors.
L
Lasse Langwadt Christensen
Guest
søndag den 2. oktober 2022 kl. 19.11.26 UTC+2 skrev John Larkin:
\"asian brands.\"? it is a TI part ..
On Sun, 2 Oct 2022 10:02:43 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
We don\'t buy \"asian brands.\"
\"asian brands.\"? it is a TI part ..
J
John Larkin
Guest
On Sun, 2 Oct 2022 10:44:06 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:
But you don\'t know where it\'s been. It might not even be a real TI
part.
<langwadt@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 19.11.26 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 10:02:43 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
We don\'t buy \"asian brands.\"
\"asian brands.\"? it is a TI part ..
But you don\'t know where it\'s been. It might not even be a real TI
part.
L
Lasse Langwadt Christensen
Guest
søndag den 2. oktober 2022 kl. 20.05.14 UTC+2 skrev John Larkin:
it\'s LCSC not some dodgy ebay shop
On Sun, 2 Oct 2022 10:44:06 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 19.11.26 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 10:02:43 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up..
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
We don\'t buy \"asian brands.\"
\"asian brands.\"? it is a TI part ..
But you don\'t know where it\'s been. It might not even be a real TI
part.
it\'s LCSC not some dodgy ebay shop
P
Phil Hobbs
Guest
Lasse Langwadt Christensen wrote:
Coincidentally, I recently ordered a couple of hundred of those on spec,
for like $66.
They are a bit suspicious in that the 100-piece price is considerably
lower than TI\'s, but we\'ll see.
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
søndag den 2. oktober 2022 kl. 20.05.14 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 10:44:06 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 19.11.26 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 10:02:43 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 18.55.09 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 08:46:13 -0700 (PDT), Lasse Langwadt Christensen
lang...@fonz.dk> wrote:
søndag den 2. oktober 2022 kl. 17.11.23 UTC+2 skrev John Larkin:
On Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
cl...@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-LM5164DDAR_C477928.html
almost 10k in stock for ~1$ each
We don\'t buy \"asian brands.\"
\"asian brands.\"? it is a TI part ..
But you don\'t know where it\'s been. It might not even be a real TI
part.
it\'s LCSC not some dodgy ebay shop
Coincidentally, I recently ordered a couple of hundred of those on spec,
for like $66.
They are a bit suspicious in that the 100-piece price is considerably
lower than TI\'s, but we\'ll see.
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
P
Phil Hobbs
Guest
John Larkin wrote:
Reverse protection is also important to protect against an input short,
which can blow up stuff by forcing currents from output to input.
That\'s one of the three ways to blow up a 317, and one of the two to
blow up an 78xx regulator. (Input overvoltage is the other main one,
and for a 317, discharging a big ADJ pin bypass backwards.
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 Sun, 2 Oct 2022 13:13:39 +0100, Clive Arthur
clive@nowaytoday.co.uk> wrote:
On 30/09/2022 21:14, John Larkin wrote:
We make a gadget that\'s powered by a 12 volt wart, and sometimes a
user applies 24 and blows one up.
We have a polyfuse and a 12 volt TVS and they sometimes fry the TVS.
It\'s posssible that most any useful polyfuse+TVS combo can be teased
to destruction.
I think Phil H mentioned some gadget, a polyzorb or something, that
would be better. I can\'t find it.
We might fine-tune the polyfuse+TVS, or maybe go polyfuse and SCR
crowbar, or something.
This is all entangled with parts availabity. Ideally the box would
just work from 12 or 24, but that has separate complications.
We once used a TI electronic fuse IC, but it liked to blow up.
12V LDO regulator with thermal shutdown.
That would work if the LDO can stand +24v input. It still needs
reverse protection.
May as well just let it work from +10 to +40. The customer can use the
wrong wart and never notice the difference.
I suspect that negative-center warts are rare these days.
My next problem is a bulletproof UVLO and switcher sequencing.
Reverse protection is also important to protect against an input short,
which can blow up stuff by forcing currents from output to input.
That\'s one of the three ways to blow up a 317, and one of the two to
blow up an 78xx regulator. (Input overvoltage is the other main one,
and for a 317, discharging a big ADJ pin bypass backwards.
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
M
Mike Monett VE3BTI
Guest
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Texas Instruments parts are made in Chengdu High-tech Zone (CDHT) in
Chengdu, a city in the southwestern region of China and considered by many
to be China\'s next major technology hub.
LCSC is in Shenzhen, so they have access to lower prices.
The LM5164 has no reverse polarity protection, but that is solved with a
simple series diode.
--
MRM
That would work if the LDO can stand +24v input. It still needs
reverse protection.
if it is always from an isolated wallwart, a bridge rectifier?
May as well just let it work from +10 to +40. The customer can
use the wrong wart and never notice the difference.
LM5164 ?
Maybe not available.
https://lcsc.com/product-detail/DC-DC-Converters_Texas-Instruments-L
M5164DDAR_C477928.html
almost 10k in stock for ~1$ each We don\'t buy \"asian brands.\"
\"asian brands.\"? it is a TI part ..
But you don\'t know where it\'s been. It might not even be a real TI
part.
it\'s LCSC not some dodgy ebay shop
Coincidentally, I recently ordered a couple of hundred of those on spec,
for like $66.
They are a bit suspicious in that the 100-piece price is considerably
lower than TI\'s, but we\'ll see.
Cheers
Phil Hobbs
Texas Instruments parts are made in Chengdu High-tech Zone (CDHT) in
Chengdu, a city in the southwestern region of China and considered by many
to be China\'s next major technology hub.
LCSC is in Shenzhen, so they have access to lower prices.
The LM5164 has no reverse polarity protection, but that is solved with a
simple series diode.
--
MRM
M
Mike Monett VE3BTI
Guest
Mike Monett VE3BTI <spamme@not.com> wrote:
Correction: With a presence in Hong Kong since 1967 and in the China mainland
since 1986, TI\'s strategy in China has always been about putting resources
closer to its customer base. TI has employees in sales and marketing,
research and development and now manufacturing in a total of 16 cities in
China: Beijing, Shanghai, Guangzhou, Shenzhen, Chengdu, Nanjing, Xi\'an,
Wuhan, Xiamen, Dongguan, Zhuhai, Nanjing, Qingdao, Suzhou, Hangzhou and Hong
Kong.
https://www.asmag.com/showpost/10657.aspx
--
MRM
Texas Instruments parts are made in Chengdu High-tech Zone (CDHT) in
Chengdu, a city in the southwestern region of China and considered by many
to be China\'s next major technology hub.
Correction: With a presence in Hong Kong since 1967 and in the China mainland
since 1986, TI\'s strategy in China has always been about putting resources
closer to its customer base. TI has employees in sales and marketing,
research and development and now manufacturing in a total of 16 cities in
China: Beijing, Shanghai, Guangzhou, Shenzhen, Chengdu, Nanjing, Xi\'an,
Wuhan, Xiamen, Dongguan, Zhuhai, Nanjing, Qingdao, Suzhou, Hangzhou and Hong
Kong.
https://www.asmag.com/showpost/10657.aspx
--
MRM
C
Clifford Heath
Guest
On 2/10/22 23:35, Mike Monett VE3BTI wrote:
I got tripped up on this recently. What\'d weird is that without the body
diode, the source and drain must be connected in the expected direction
(and it sorta works) but with the body diode, it *must* be in the
reverse direction. Very confusing at first sight.
Clifford Heath.
Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:
look closer at the schematic, the reverse protection does work
the first FET is reverse so initially the body diode will work as a
series diode and when the FET turns on so there is no voltage drop
Very nice catch. It works. Thanks.
I got tripped up on this recently. What\'d weird is that without the body
diode, the source and drain must be connected in the expected direction
(and it sorta works) but with the body diode, it *must* be in the
reverse direction. Very confusing at first sight.
Clifford Heath.
L
Lasse Langwadt Christensen
Guest
mandag den 3. oktober 2022 kl. 00.40.26 UTC+2 skrev Clifford Heath:
fets without a body diode are very rare
On 2/10/22 23:35, Mike Monett VE3BTI wrote:
Lasse Langwadt Christensen <lang...@fonz.dk> wrote:
look closer at the schematic, the reverse protection does work
the first FET is reverse so initially the body diode will work as a
series diode and when the FET turns on so there is no voltage drop
Very nice catch. It works. Thanks.
I got tripped up on this recently. What\'d weird is that without the body
diode, the source and drain must be connected in the expected direction
(and it sorta works) but with the body diode, it *must* be in the
reverse direction. Very confusing at first sight.
fets without a body diode are very rare