Absolute maximum voltage -- how long can digital chips stand it?

Are you sure you understand what you're asking? There's often a disclaimer in the spec that the device is not guaranteed to do anything at the absolute maximum voltage except survive.

If you're suggesting that you will operate ANY component at its absolute maximum voltage, you should inform your employer so they can fire you before you put them out of business.

Typically, no way to say

Typically, 20 years?

Tests I have made once on a 4000 series CMOS designed for abs max 18V failed at

21V. But that test was highly un-scientific

Regards

Klaus

I don't want to run at that voltage. I'm just asking because others do, and I'm actually trying to talk them out of it.

The chips are DDR3 DRAM recommended for 1.50V or 1.35V and rated 1.975V absolute maximum. A few retail brands of DDR3 modules are sold with recommended voltages of 1.9V - 2.1V, those recommendations coming from the module marketers, not the chip makers, and I just want to know how long they'll likely last.

There's probably no difference.

Failure rates, absent abuse, are measured in FITS, where one FIT is one failure per billion hours. Digital ICs are usually a few FITS for simple stuff, numbers like 20 or 100 for an FPGA maybe. Some vendors will supply numbers if you search around or ask directly.

Reliability does go down as temperature goes up, about 2:1 incease in FITS per 10 degrees C. So if higher supply voltage makes the chips get hotter, that could matter.

--

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There's no benefit to running something like a DRAM at any but its design-center voltage, and some small risk. We only push parts to (and sometimes beyond) abs max specs when there is a big performance payoff.

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John Larkin         Highland Technology, Inc 

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http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

21V. But that test was highly un-scientific

We've used some opamps rated at 12 max, and they failed at 12.

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John Larkin         Highland Technology, Inc 

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http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

John Larkin a écrit :

at 21V. But that test was highly un-scientific

Interesting. Any ref?

--
Thanks, 
Fred.

at 21V. But that test was highly un-scientific

Harris, now Intersil, HFA1130 clamp-amps. 11 volts seems OK.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

failed at 21V. But that test was highly un-scientific

As a student I bought a few expensive Intersil chips for our RF institute. They were 5V nominal and something like 6V max. They would not work at all unless they saw at least 6.7V. Called them, was brushed off rather impolitely, they would not replace them. I never designed in an Intersil part in my whole career.

--
Regards, Joerg 

http://www.analogconsultants.com/

failed at 21V. But that test was highly un-scientific

The clamp-amps are cute, but they have way too much personality.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation

failed at 21V. But that test was highly un-scientific

I like electronic parts to be more on the disciplined side :-)

Reminds me of an old friend. After a very long military career he started at an electronics company. Left after a few years. "So you didn't like the job?" ... "Oh, I did. I just could not stand civilians, with all their personality issues".

--
Regards, Joerg 

http://www.analogconsultants.com/

If it's MOS then the most likely failure mechanism is some kind of gate oxide overstress breakdown. Failures won't be measured in FITS then.

The answer is "indefinite." I always thought the absmax rating was kind of stupid since nobody specs the time it will survive. Parts with short circuit protect often have an indefinite time as well, though short circuit protection is on a better engineering footing that absmax. That is a design engineer understands the innards of short circuit protection, but there can be nuances in stressing devices.

In the ATE characterization program (not to be confused with a test program), you typically stress a part for a second. Nobody is going to waste a second of test time for this in real life, i.e production.

Some companies will run the characterization test under normal conditions, stress the part, then run it again to see if the numbers change. This is all different from company to company. I've yet to understand what all this ISO9xxx crap accomplished since quality flow is not standardized to the best of my knowledge. Or if it is, some companies go beyond the standard. The ISO standards make you document what you do, but don't specifically say what to do. [My opinion as someone who never worked in QA.]

With increased supply voltage, you are fighting stronger "opposing" devices, so the threshold usually goes up, as in further from the rails. [The opposite sex device starts at the full supply voltage, so it is at full strength.] In any event, it is a bad idea to run at elevated voltages.

DRAMs are quite sophisticated these days, employing PLLs and such. Some have thermal sensors. Why play with fire?

Most of the intel mobos these days use 2x interleaved scheme. The older mobos were 3x. They made an "extreme" series that was 4x but the performance wasn't improved at all. In most cases, you are better off having more ram than less ram at a faster speed.

"Power dissipation goes up as the square of voltage" and "current goes up (somewhat)" is double-counting the increase. P~CfV^2.

The DRAM tester I have is out of date, but a lot of memory failed when tested at just 3% above nominal.

Let 'em burn >:-} ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

I located most bad early RAM chips with a calibrated fingertip. Cold=dead. Warm=working. Hot=defective.

CMOS runs fastest when at cold temperatures. ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.