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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: Ever smaller DC-DC converter modules by TI
Date: Mon, 2 Sep 2024 09:07:48 -0000 (UTC)
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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:
>>>>>  
>>>>> 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 didnΓÇÖt 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 

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