How to read datasheets
On a prototype board, a surge was found that momentarily pushes the supply voltage above its absolute maximum rating. The IC still works normally afterward. Which is the appropriate way to think about this?
- AThe IC may have degraded internally and its reliability is no longer guaranteed, so fix the surge, replace the IC and re-evaluate
- BSince it works normally, it can be judged undamaged, and you can proceed to mass production without any particular countermeasure
- CAbsolute maximum ratings apply to continuously applied values, so exceeding them for a very short time is not a particular problem
Show answer and explanation
Answer: A. The IC may have degraded internally and its reliability is no longer guaranteed, so fix the surge, replace the IC and re-evaluate
Absolute maximum ratings must not be exceeded even momentarily, regardless of duration. Even if the device works right after the event, the gate oxide, junctions or protection elements may be partially damaged, and failures can appear later as increased leakage current or shortened lifetime. Parts that have been overstressed should therefore be treated as outside the reliability guarantee and replaced, and the evaluation repeated after suppressing the surge with TVS diodes, filters or the like. Datasheets typically include a note such as "Stresses beyond those listed may cause permanent damage to the device."