Re: Ever smaller DC-DC converter modules by TI

john larkin <jlarkin_highland_tech> wrote:

On Mon, 2 Sep 2024 09:07:48 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
 

Jan Panteltje <alien@comet.invalid> wrote:

On a sunny day (Sun, 1 Sep 2024 17:43:26 +0200) it happened Arie de Muijnck
<noreply@ademu.nl> wrote in <nnd$2f75283c$0bf25191@b9829d5a22e7a1d0>:
 

On 2024-09-01 17:29, Arie de Muijnck wrote:

On 2024-09-01 16:35, john larkin wrote:

Jan Panteltje <alien@comet.invalid> wrote:

Ever smaller DC-DC converter modules by TI:
?á
https://www.electronicdesign.com/technologies/power/article/55134121/electronic-design-tis-magnetic-materials-and-packaging-magic-help-slash-dc-dc-module-size-even-further
This innovation is based largely, but not entirely,
on advances in magnetic materials,
and it didn?ÇÖt come quickly.
Noted Jeff Morroni, director of power management research and development
at TI's Kilby Labs,
 
For example:
1.8 to 5.5V in to 5.5V out at 5.5A size 2.5 x 2.6 mm boost module
More examples in link.
 

 
1W isolated 5 -> 3.3V, 4x5x1 mm, SS, *76 MHz* switching frequency, for
$1.50 @ 1ku?
 
Potentially pretty cool!
 
Cheers
 
Phil Hobbs
 

 
I noticed in the datasheet to avoid disabling it under full load.
To me that reads the shrapnel would reach the ceiling...
 
Arie

 
After better reading the datasheet of the boost converter, TPSM81033,
most interesting for me right now.
And not disabling but removing the input voltage. Like with the good old
LM78xx regulators.
 
"
Device Limitations (intended to be removed for final material):
1. Inductor current limit function is not optimized. TI don't recommend
to use TPSM81033 at the
condition that the input current is higher than 5A. Final material is
expected to improve the current
limit function.
2. TPSM81033 doesn't support to remove input voltage at heavy load. TI
recommend to remove
input voltage at no load, or connect EN to GND first with load and then
remove input voltage. Final
material is expected to support remove input voltage at heavy load.

"
 
That sure is a big limitation!
 

 
I’ll certainly be reading the datasheet carefully before using the part,
but I expect that it’s not a big worry in real life.
 
You’re going to have some sort of reservoir cap on the input, and with a 76
MHz switching frequency, its discharge will be nice and smooth. 
 
It would take work to cut off the input supply fast enough to cause
inductive problems.
 
Cheers
 
Phil Hobbs

 
I'm always suspious when I see a note like that on a data sheet.
Oftimes, they are hiding a latchup or something.
 
If it does latch up, a brief brownout, or some spike, might fry the
thing. I'd get an eval board and play with one before designing it
into anything.
 

No fear. I don’t use any switcher chips that I haven’t tried out, good and
hard.

My soul was seared by a TI part that the datasheet swore would keep on
PWMing right down to zero load current. They made a big deal about it.

Aha! I says, says I, “Perfect for my fancy isolated triple-output flybuck!”

After I’d designed it into the guts of a biggish board, it turned out to be
all lies—with a light load on the main output, it went into burp mode and
the isolated outputs collapsed.

Barstids.  Never again.

Cheers

Phil Hobbs

Sometimes the current ratings are optimistic too.
 
 

--
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics