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'[EE] Wide input voltage step down SMPS IC out = 5V'
2011\10\30@162850 by Electron

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Hi,
could anybody please suggest me a good and possibly cheap (it's not for
a one-off) small, nice, step down SMPS IC with wide input voltage range
(say 6..40 or more V) out = 5V (even better, dual out 5V / 12V ) 100+mA?

Thank you!
Mario

2011\10\30@173612 by M.L.

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On Sun, Oct 30, 2011 at 4:28 PM, Electron <spam_OUTelectron2k4TakeThisOuTspaminfinito.it> wrote:
>
> Hi,
> could anybody please suggest me a good and possibly cheap (it's not for
> a one-off) small, nice, step down SMPS IC with wide input voltage range
> (say 6..40 or more V) out = 5V (even better, dual out 5V / 12V ) 100+mA?
>
> Thank you!
> Mario

MCP16301 might work.
http://ww1.microchip.com/downloads/en/DeviceDoc/25004A.pdf

-- Martin K

2011\10\31@055643 by RussellMc

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part 1 2492 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

Hi,
could anybody please suggest me a good and possibly cheap (it's not for
a one-off) small, nice, step down SMPS IC with wide input voltage range
(say 6..40 or more V) out = 5V (even better, dual out 5V / 12V ) 100+mA?


40V+ input narrows the range and "cheap" seems to vanish.

__________________

LM5085
$1.24/1000 Digikey
$1.07/10000 Digikey

Reasonably nice IC if $1+ OK.
External FET (more $)
4.5 - 75 Vin
External FET
Freq prog to 1 Mhz.
95% at 500 mA out at 7V in
80%+ at higher Iouts at most Vins.
MSOP-8, LLP-8 (3mm x 3mm)


http://www.national.com/ds/LM/LM5085.pdf


___________________

Worsish in some ways but aimed at efficiency at lower loads with PFM
Graphs on pages 23 + 24 would give you a fright when you first met them
being implemented in action.


eg Infineon offer eg  TLE 629

TLE6389-3G V50CT-ND<http://search.digikey.com/us/en/products/TLE6389-3G%20V50/TLE6389-3G%20V50CT-ND/2231231>

However, as that uses an external FET switch a little playing could extend
the range indefinitely

___________________

But, there's always the time honoured MC34063 which has a switch abs max
voltage of 40V stand alone and as high as you like with external FET.
Only 100 kHz ish so larger L's but very minimal parts count up to ~~~ 40V.
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00001232.pdf

See figs 15+16 for minimum parts buck cct. and PCB layout
IC. 3R, 1C, D, L + 2 x filter caps.

Not marvellous efficiency at low Vin due to non saturating darlington
driver but can add external FET if desired.

$0.19 / 1000 Digikey
$0.124/50,000 Digikey
$US0.05 - 0.10 / China (Motorola licenced copy)

_______________________

"My" "God's switching Regulator" [tm] will do this with 3 jellybean
transistors 4R,  1D. 1L, 1Z, 2 x filter caps.

Attached is someone's apparently parallel reincarnation of my design.

That's from here : http://sound.westhost.com//appnotes/an006.htm

With a constant current version here
http://sound.westhost.com//appnotes/an003.htm

I've had versions of this that ran at Vin from 12V to 200V and Vout = 12V..
Below 12V Vout tracked Vin less Q3 saturation.
There are 10,000++ of these "out there" so ignore people who say it won't
work :-).
[It's actually a 'hysteretic converter' but I had not met them when the
concept dropped/was dropped fully formed into my mind in time of need :-).]





                Russell


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2011\10\31@063113 by RussellMc

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part 1 1076 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

Attached is a cct of my high voltage input version from February  2001 (how
the years fly).
On line with notes here
http://www.piclist.com/techref/postbot.asp?by=thread&id=%5BEE%5D+Low+cost+switching+regulators&w=body&tgt=_top

P Channel MOSFET used on high side. Bipolar OK especially at low power.
QBUK2 is high voltage transistor (MPSA42) due to voltage input.
RBUK3 also has full HV across it.

Voltage is somewhat above Vzener.
Zener runs on soft knee as shown but end result is amazingly good.
Much better Vin and load stability than would be expected from its
appearance.
(The 2 transistor "Black Regulator"  has fewer parts but is much more load
sensitive.

Oscillation is "chaotic" - nicely spread spectrum noise wise.
Ripple on CBUK2 and zener noise both contribute to switching point.
Some people have added positive feedback to formalise the feedback. eg
(probably) a resistor from hot end of coil to base of QBUK1 would add
positive feedback and hysteresis.




Russell



GSR _GSR


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2011\10\31@163444 by Jesse Lackey

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I use this:

TI TPS54160DGQ (mouser 595-TPS54160DGQ) in two designs with a manufacturing quantity total approx 1K, done in runs of 100.  It probably fails the cheap requirement, but it does go above 48V (my primary criterion).

J



Electron wrote:
>
> Hi,
> could anybody please suggest me a good and possibly cheap (it's not for
> a one-off) small, nice, step down SMPS IC with wide input voltage range
> (say 6..40 or more V) out = 5V (even better, dual out 5V / 12V ) 100+mA?
>
> Thank you!
> Mario

2011\10\31@174515 by M.L.

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On Sun, Oct 30, 2011 at 4:28 PM, Electron <.....electron2k4KILLspamspam@spam@infinito.it> wrote:
>
> Hi,
> could anybody please suggest me a good and possibly cheap (it's not for
> a one-off) small, nice, step down SMPS IC with wide input voltage range
> (say 6..40 or more V) out = 5V (even better, dual out 5V / 12V ) 100+mA?
>
> Thank you!
> Mario
>


This circuit has been modified at times to take a much higher input voltage:
http://www.romanblack.com/smps/smps.htm

-- Martin K

2011\10\31@175836 by RussellMc

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> This circuit has been modified at times to take a much higher input voltage:
> http://www.romanblack.com/smps/smps.htm

The "Black Converter" is cost efficient and compact but is far less
regulated than 'my' 3 transistor GSR. The difference is significant in
real world applications.

Roman produced  his circuit based on a relay driver circuit suggested
by Richard Prosser in response to a long ago PICLIst design challenge
where I put my design up as straw-man. If the regulation  is
acceptable Roman's wins out slightly over mine on price.



   Russell McMaho

2011\10\31@182515 by M.L.

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On Mon, Oct 31, 2011 at 5:57 PM, RussellMc <apptechnzspamKILLspamgmail.com> wrote:
> The "Black Converter" is cost efficient and compact but is far less
> regulated than 'my' 3 transistor GSR. The difference is significant in
> real world applications.
>
> Roman produced  his circuit based on a relay driver circuit suggested
> by Richard Prosser in response to a long ago PICLIst design challenge
> where I put my design up as straw-man. If the regulation  is
> acceptable Roman's wins out slightly over mine on price.
>

Possibly useless anecdote:
I designed a buck converter based on the TL432. Regulation was
"perfect" but efficiency wasn't so great. Extremely cheap I'd say.

--
Martin K.

2011\10\31@190339 by Dwayne Reid

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At 04:24 PM 10/31/2011, M.L. wrote:

>Possibly useless anecdote: I designed a buck converter based on the
>TL432. Regulation was "perfect" but efficiency wasn't so great.
>Extremely cheap I'd say.

I assume that you meant TL431 rather than TL432?

Do you have the design posted anywhere?

Thanks!

dwayne


-- Dwayne Reid   <.....dwaynerKILLspamspam.....planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
http://www.trinity-electronics.com
Custom Electronics Design and Manufacturing

2011\10\31@191413 by Mark Rages

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On Mon, Oct 31, 2011 at 5:03 PM, Dwayne Reid <EraseMEdwaynerspam_OUTspamTakeThisOuTplanet.eon.net> wrote:
> At 04:24 PM 10/31/2011, M.L. wrote:
>
>>Possibly useless anecdote: I designed a buck converter based on the
>>TL432. Regulation was "perfect" but efficiency wasn't so great.
>>Extremely cheap I'd say.
>
> I assume that you meant TL431 rather than TL432?
>

"The TL432 has exactly the same functionality and electrical
specifications as the TL431, but has different pinouts."  from
http://www.ti.com/product/tl432

-- Regards,
Mark
markrages@gmai


'[EE] Wide input voltage step down SMPS IC out = 5V'
2011\11\01@054556 by Electron
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Wow, how many interesting replies and things I have to read and
learn now.. thanks a lot, my day has been allocated. :-)

2011\11\01@061139 by RussellMc

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>>>Possibly useless anecdote: I designed a buck converter based on the
>>>TL432. Regulation was "perfect" but efficiency wasn't so great.
>>>Extremely cheap I'd say.

>> I assume that you meant TL431 rather than TL432?

> "The TL432 has exactly the same functionality and electrical
> specifications as the TL431, but has different pinouts."  from
> http://www.ti.com/product/tl432

Worse!!!!
The TL431 and TL432 will often be pinout variants but some
manufacturers make a TL432 with a TL431 pinout.

Manufacturer and distributor must be specified and locked in with any
variation from this requiring change control and testing and
certification of the alternative. Enforcing that from a distance
without "being there" relies totally on integrity and buy-in and
competence of the manufacturer. That's an unrealistically large amount
to expect of a manufacturer in many cases.

Some years ago I saw (afterwards & from a distance) a complete
production  batch of products made and shipped with a pinout-incorrect
variant of the TL431 SOT-23 pkg installed.  These had a significantly
bad  effect on performance. and the factory engineers involved were
aware that performance was not as it should be but did not know why
and did not report it and afterwards justified it with an explanation
re how they thought that was what was wanted. Complete swapout of PCBs
or recall of that batch of product was required.


       Russell McMahon

2011\11\02@175943 by M.L.

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On Tue, Nov 1, 2011 at 6:10 AM, RussellMc <apptechnzspamspam_OUTgmail.com> wrote:
> Manufacturer and distributor must be specified and locked in with any
> variation from this requiring change control and testing and
> certification of the alternative. Enforcing that from a distance
> without "being there" relies totally on integrity and buy-in and
> competence of the manufacturer. That's an unrealistically large amount
> to expect of a manufacturer in many cases.

Which is why I know the TL431 as the "TL431CDBZR" from memory.

-- Martin K

2011\11\02@180621 by M.L.

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On Mon, Oct 31, 2011 at 7:03 PM, Dwayne Reid <@spam@dwaynerKILLspamspamplanet.eon.net> wrote:
> At 04:24 PM 10/31/2011, M.L. wrote:
>
>>Possibly useless anecdote: I designed a buck converter based on the
>>TL432. Regulation was "perfect" but efficiency wasn't so great.
>>Extremely cheap I'd say.
>
> I assume that you meant TL431 rather than TL432?
>
> Do you have the design posted anywhere?
>
> Thanks!
>
> dwayne

I'm really busy with work on a customer site so I'll have to get back
to you. I have it soldered together but I can't seem to find a drawing
of the schematic. I think I meant the TL432, if that's the version of
the TL431 with lower minimum cathode current.
-- Martin K

2011\11\02@190137 by RussellMc

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TLV43x is low voltage reference version = 1.25V.
TL43x is 2.5V reference version.

TLV has notably lower Imin_reg than TL version (about 80 uA vesis 400
uA from memory.

Either would work as a switching regulator.
Main limitation is low frequency response.

Out of head.

Buck regulator.
High side P channel MOSFET feeds inductor o output = std Buck.
P Channel drain to reverse biased diode to ground = std Buck.

TL431 anode grounded.
2 resistor divider across output - tap to TL431 gate.or ref pin.

Small pnp emitter to V+, collector to MOSFET gate. resistor base to V+
say 100k. resistor base to TL431 Cathode = ? 10k.
MOSFET gate resistor to ground. Say ? 1k.
___

When output high TL431 turns on.
TL431 turns on PNP.
PNP turns off FET.
Inductor delivers energy till I = 0.

Output falls.
TL431 turns off
MOSFET turns on.
Voutrises.
Cycle repeats.



 Russell



Cycle completes.






On 3 November 2011 11:05, M.L. <KILLspammKILLspamspamlkeng.net> wrote:
{Quote hidden}

>

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