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Manufacturer using part over maximum ratings, is it safe?
Manufacturer using part over maximum ratings, is it safe?
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Old 1st August 2019, 07:00 PM   #11
Mooly is offline Mooly  United Kingdom
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Manufacturer using part over maximum ratings, is it safe?
These CMOS type switches, and it could even be the same part number, were used extensively in mid price music systems from the likes of Aiwa and many others in the late 80's and 90's and they were a fairly regular failure item. Fwiw, these systems used nothing like -/+20, more like -/+9 from memory.
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Old 1st August 2019, 08:39 PM   #12
analog_sa is online now analog_sa  Europe
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Manufacturer using part over maximum ratings, is it safe?
Quote:
Originally Posted by ej25awd View Post

Kudos Salberg for an informative and quality post!
+1
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Old 2nd August 2019, 02:51 AM   #13
davidsrsb is offline davidsrsb  Malaysia
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Quote:
Originally Posted by simon7000 View Post
A manufacturer can get parts tested for a particular specification. That looks like what was done here.
I have never seen a screened part not marked with a special "house number"
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Old 2nd August 2019, 03:34 AM   #14
PRR is offline PRR  United States
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Quote:
Originally Posted by Salberg View Post
...looking in the datasheet the maximum supply voltage is Ī 20V...
ABSOLUTE MAX!

Next page, Operating Max, is +/-18.5V.

Get it down to there.

There is an anecdote in the studio console world. A console maker asked for specially selected TL072 chips to stand +/-20V (normally rated +/-18V). They did have a special part number. However after 30++ years many have failed.

True story: I ran 28V chip-amps on 35V. Worked for 9 years and then dead. Replaced, worked another 9 years, dead. By this time they were on Lifetime Buy, so I got 2 more, and then quit that place.
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Old 2nd August 2019, 03:55 AM   #15
simon7000 is offline simon7000  United States
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Originally Posted by ej25awd View Post
Not another anecdote!

Do you have any shred of proof or evidence that supports this unsubstantiated statement of yours?

What is true to one case doesn't necessarily apply to another.
No anecdote having real experience in the field both with the designers and service folks. It is a very common practice as noted by others here.

Do you really think running an 18 volt nominal part at 23 volts would get past a design review? Even make it past the warranty period?

Yes there are actual products out there where parts are used in an off data sheet parameter method. Not surprisingly high warranty failure rates and quickly redesigned. Almost an unknown issue from major manufacturers.

Last edited by simon7000; 2nd August 2019 at 04:00 AM.
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Old 2nd August 2019, 04:07 PM   #16
ej25awd is offline ej25awd  Canada
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I'm fully aware of discrete devices that are cherry-picked, op amps tested for noise, etc. Testing cost money. Bean counters in major manufacturers of mass consumer electronics want to reduce their BOM cost not the other way around yet you suggest the contrary.

The OP is talking about a Sanyo/ON LC78212 CMOS IC which is completely different from what you experienced in your lifetime. If you want to expand your insider knowledge about YOUR own subject, open a new thread instead of thread-jacking this one.

You talk about an imaginary Marantz PM17 II design review that you weren't part of and even have insider knowledge on how it transpired. Seriously?

The OP did his failure analysis and I agree with his assessment.

I think simple, it is elegant. Over analyzing makes you crazy.
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Old 2nd August 2019, 04:25 PM   #17
simon7000 is offline simon7000  United States
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Wow you are psychic... not. I have used the ON LC78212 and similar units in some of my designs. I also have worked with some of the folks who do designs for Marantz and have a friend who consults with and reviews some of their products.

Using a selected part is usually cheaper than than adding parts. Screening for noise is not. IC processes of often run at 36 volt-ish limit.

I also have mentioned the best solution is to add zeners in series with the voltage rails to drop the voltage, but obviously you didn't read or comprehend that.

BTY today I got the go ahead for a new gizmo I designed. It will be a medium size run of 10,000 pieces.

Last edited by simon7000; 2nd August 2019 at 04:29 PM.
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Old 2nd August 2019, 06:41 PM   #18
ej25awd is offline ej25awd  Canada
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Adding/modify the Zener was posted before yours. That was the obvious solution to a very simple problem. Can we move on unless you are the one who designed the PM 17 II and have actual information that support your baseless claims?

More anecdotal stuff. It never ends.
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Old 2nd August 2019, 07:17 PM   #19
simon7000 is offline simon7000  United States
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So you like to post and don't even know what an anecdote is... So troll on.
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Old 2nd August 2019, 09:05 PM   #20
ej25awd is offline ej25awd  Canada
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Quote:
Originally Posted by simon7000 View Post
So you like to post and don't even know what an anecdote is... So troll on.
Unsubstantiated claims and hearsay are all anecdotes = tale. Your posts are so full of it.

I should stop feeding a troll

Added to ignore list. Done!
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