How can a 555 timer be damaged

antknee said:

Why cut the legs off?

Antknee.

Click to expand...

It's to stop you from using it in case you miss the bin and find it later.

JimB said:

IAnother thing which will damage ICs is static electricity.
When I am working on a circuit board I wear an anti-static wrist strap which is earthed.
Why? because of painfull expensive experience, having damaged a couple of expensive modem ICs (about £11 each) my wife never let me live it down!

Click to expand...

I agree, I'm in the process of returning some RAM I purchased off ebay because it didn't come wrapped in anti-static packaging but printer paper and bubble wrap.

I would've happily paid more for the proper packaging and will not use anything that might fail later as ESD can make components unreliable.

Lol. I think it is in case you miss the bin and tread on it barefoot later!

antknee said:

Lol. I think it is in case you miss the bin and tread on it barefoot later!

Click to expand...

I do it just to be sadistic.

That's happened to me before.

I think it's stupid that they don't just incorperate a protection diode on the + and - power supply pins (with all of the rest of the internal circuitry, a few extra silicon nano parts won't mak a difference). Then we wouldn't have this problem!

It could be done but it would increase the minimum operating voltage by 0.7V and reduce the maximum output voltage by 0.7V so would annoy people like me who design things correctly most of the time and will only add a protection diode if it's required.

Guess why it is called an idiot diode?

The chip is dead, rest assured it is dead and unlike Lazarus it will not return from the dead. It has zero value for anything rather than serve as a reminder it was unwise to reverse power to it.

How can I be sure the chip is dead? Should I place faith in the words in this thread by experienced people who say connecting the chip in a reverse polarity mode will in fact kill it?

Yesterday when I read this thread I didn't bother to post. However, at work today I had a quiet moment so I tried a test. I selected a victim (err rather healthy 555 timer chip) from a bin in my lab area and bread boarded it. I then powered it using reverse polarity @ 15 VDC from a power supply capable of 1 Amp. I powered the chip a few seconds and it got real hot real fast. Total time maybe 3 to 5 seconds if that. I then powered the chip correctly and again it got real hot real fast. I then took another 555 and correctly powered it and it did not get hot.

Rest assured that reverse polarity on a 555 will n fact render a quite dead useless chip. If I would have had more time I guess I could have instrumented the chip and measured current and temperature rise but I saw no need since it was a given the 555 would literally be toast.

Your chip is dead and that is about it. If it were simple to do I would send you some but alas I guess that wouldn't be easy. I suggest a decent funeral and move on with life.

Condolences
Ron