Re: Operating temperature derating

Don Y <blockedofcourse@foo.invalid> wrote:

On 6/7/2024 2:59 PM, legg wrote:

On Fri, 7 Jun 2024 12:45:24 -0700, Don Y <blockedofcourse@foo.invalid>
wrote:
 

On 6/7/2024 6:35 AM, legg wrote:

Commercial considerations of free enterprise have always pushed
human behaviour towards banditry, so what can I tell you?

 
But banditry would suggest taking advantage of the customer.
This is the opposite; the customer gets *more* performance
than the stated capabilities.
 
But, no way to know HOW MUCH more!

 
What exactly IS your concern?

 
I want too know how much MORE than the published/unpublished operating
limits one can reasonably expect from a piece of kit -- given that
these limits don't seem to TRULY represent "maxima".
 
We have a general idea of the types of components used in these
things and realize that their operating limits usually exceed the
published limits for the composite device -- often by a lot!
 
This suggests (to me) that the published limits aren't backed by
"real" engineering or stress testing.  But, rather, likely arise
from marketing specs... someone making a SWAG as to how customers
will LIKELY use the devices and not what their actual design limits
happen to be.
 
[Given that using ANYTHING beyond its operating limits leaves you
without a leg to stand on, it would be nice to have some idea as to
what a reasonable expectation for those limits might be, despite
the "fluff" on the spec sheet.  E.g., I would be really pressing my
luck to use something at 80C in that most components would likely
not be specified at those extremes.  But, 55C for a 50C-specified
device?  60C?]
 
 
 

We’ve had chipmaking folks here (including Miso, iirc) say that the abs max
ratings are primarily marketing driven, like most of the rest of the
datasheet.

You find out what your major customers are going to do with the part, and
derate it to match. That way you sell parts and still get to have a quiet
life.

Of course there are things like delamination, overvoltage and
electromigration that cause lifetime issues rather than prompt failures.

Cheers

Phil Hobbs

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