Author Topic: ICs getting addicted to higher voltages?  (Read 2673 times)

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Offline ArtlavTopic starter

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ICs getting addicted to higher voltages?
« on: September 12, 2014, 11:03:04 pm »
What happens when a 3.3V device/IC is ran at 4-5V?

I had two cases like that.
One was a camera with an external power supply that was supposed to be 3.3V being used with a 4.2V supply.
It ran fine for a while, but after some time it stopped working with batteries, and won't start from anything too far below 4V.

In another case, i ran a 3.3V IC at 4V (thinking it was a 3-5V version).
I noticed after a few days of that, and got it down to 3.3V.
It kept on working, however it won't accept I2C input signals at 3.3V any more.
4V I2C works, however, even with 3.3V supply.

It seems that ICs are getting addicted to high voltage, once they tasted it.

Question is - how does it work?
I would have expected a gate breakdown somewhere, or internal resistors overheating, or something else that is followed by smoke.
 

Offline ConKbot

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Re: ICs getting addicted to higher voltages?
« Reply #1 on: September 13, 2014, 01:31:40 am »
Well at least you have better luck then my co-worker who was doing a project with an op-amp at home.

"It works at first but then the op amp stops working"
'Whats your supply voltage?'
"12v.."  measures it, and the meter shows 12.1v "see?"
'The absolute max in the datasheet says 12.0v and youre feeding it 12.1, and youre wondering why its dying?'
"Yeah, its not that far over..."
'Just put a diode on the power line and it will bring it down and it'll be fine'
"ok"
 

Offline bktemp

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Re: ICs getting addicted to higher voltages?
« Reply #2 on: September 13, 2014, 05:39:15 am »
It seems that ICs are getting addicted to high voltage, once they tasted it.

Question is - how does it work?
I would have expected a gate breakdown somewhere, or internal resistors overheating, or something else that is followed by smoke.
If the IC runs at a higher voltage for some time and it does not break down, it can change its electrical characteristics. I think this comes from some electrons getting trapped somewhere in the internal transistors and changing their threashold voltages.
 

Offline amyk

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Re: ICs getting addicted to higher voltages?
« Reply #3 on: September 13, 2014, 12:32:51 pm »
The PC overclocking community has known about this effect for a long time - CPUs that were overvolted and overclocked for some time stop working at stock speeds and voltages, and on some of them the voltage required to keep it working goes up with time. I believe it's been attributed to electromigration.
 

Offline SArepairman

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Re: ICs getting addicted to higher voltages?
« Reply #4 on: September 13, 2014, 09:44:09 pm »
 

Offline timb

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Re: ICs getting addicted to higher voltages?
« Reply #5 on: September 13, 2014, 11:50:09 pm »



Push it to the lemons! Walk along the grazers edge, don't look sour or you're finished! Open up the lemons! Past the point of no refunds; ohhhh yeah! Welcome to the lemons!


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Any sufficiently advanced technology is indistinguishable from magic; e.g., Cheez Whiz, Hot Dogs and RF.
 


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