LTC1290CCN Chip Failure

What does Linear Technology have to say?

I don't recall working on anything with this chip in it, but I have seen a number of failures with various DIP packages. Here are some general things to look at:

Is there any relation between failure and humidity? Is there evidence of corrosion or tarnish on the pins? Are there units using chips from a previous lot, with the same system design, all or most still working without these failures? If the answer to the last question is yes, that narrows trouble-shooting possibilities considerably.

Some possible failure modes involved include:

Internal corrosion due to pre-package-closure contamination (mfg. defect);

Failing die bonds (mfg. defect);

Diffusion-related device failure (mfg. defect or thermal damage due to heat management problems - see the last paragraph of this reply);

Package seal failure permitting moisture penetration in humid conditions (mfg. defect or system assembly process error);

Progressive failure caused by repeated ESD strikes (system design or application problem).

On older equipment, I have seen problems with poor connections due to tarnished pins in devices seated in sockets, especially if the sockets do not guarantee gas-tight interfaces. Sometimes I can "repair" the circuit by polishing the pins with a pencil eraser, although it is often necessary to also replace the socket if it has tin-plated flat contacts. Another possibility is a metallurgical problem between pin and solder - this could be a result of bad plating on the IC pins, or if thermal cycling is an issue, solder fatigue (often the solder is visibly crumbling or cracking).

One other possibility is latch-up caused by momentary power glitches. Perhaps a chip bypass capacitor is failing.

If you have a thermal (IR) camera, take a look at the temperature profile of good and bad systems under typical operating circumstances. The failure rate goes up exponentially with temperature, so if the IC is operating close to its upper limit, you can expect to see problems sooner rather than later.

Hello Gas Man,

Are the inputs to your a/d circuit present before you power up the a/d cct?

Are any of the inputs beyond the input spec of the device?

Do the inputs share a common ground with the a/d circuit?

Any of the above could cause your problems.

Hope this helps.

Can you post a circuit diagram: including the full path of the analogue inputs and any power supplies.

I suggest performing a "root cause" failure analysis by an experienced lab, on a number of units. The results will tell you what caused the failures. Such an analysis can be time consuming and costly. Replacing the parts may be a more satisfactory approach.

You may have a batch of forged chips, you need to send them to the purported manufacturer to see if they are truly theirs or not.....

This is a significant problem today......