Other Parts Discussed in Thread: MSP430F6736A, TIDM-AUX-MODULE
Customer running temperature tests on MSP430F6749A. It was observed that RTC becomes inaccurate when tested at 60 degC. Instead of having drifts, customer found out that RTC would, at undetermined intervals, miss 5 counts (5 x seconds counters). Attached is the scope captures on 2 separate instances.
Other points:
1. MSP430F6749A RTC works well at 50 degC and below.
2. Using the exact same Crystal, and load caps, on MSP430F6736A, there is no such issue. (They had been shipping in ~500KU volumes with this same crystal on MSP430F6736A for ~2 years)
3. Customer can accept drifts due to temperature. But this problem is not a drift, but a consistent behavior of skipping 5 counts.
Question:
What could cause MSP430F6749A to have such type of failure, and how to fix it?