This is from a memo from UTMC (Tony Jordon) to a GSFC contractor dated Sept. 12, 1997
Subject: RADPAL Anomaly
A recently reported anomaly in the RADPAL’s operations has been confirmed but not fully characterized at this time. The purpose of this memorandum is to convey what we know today. Further documentation on the problem will be made available as more information is collected. Engineers expect to complete an initial evaluation by September 19th 1997. The initial evaluation will characterize the performance of units shipped year to date and hopefully identify a work-around, screen, and temperature and operating profile. Wafer lots in inventory will also be evaluated for this anomaly. At this time we believe the anomaly affects QML A, V, and RHR product only. At 25°C the part meets the data sheet over the specified power supply range of 5 volts +/- 10%. Only RADPAL’s programmed with registered outputs (i.e., sequential logic) will exhibit the anomaly.
From the evaluation performed to date we have observed the following. The anomaly is limited to the asynchronous reset of the RADPAL’s macro-cell circuit during power-up. Failure mode: the power-on reset circuit fails to release (i.e. logically negate) at power supply voltages (VDD) between 4.8V and 5.0V at -55°C. As temperature increases the voltage threshold decreases. Once VDD exceeds the voltage threshold, operation to the data sheet is achieved (i.e., 5 volts +/-10% over the full military temp range). Unprogrammed parts behave better than programmed parts either due to self-heating or ground bounce.
The profile of the decrease is close to linear but has a second or third order profile (i.e., slight curve). At -40°C, with the limited data taken to date, the threshold ranges from 4.7 to 4.9. The variance from device to device is 200mV. At 25°C data shows that all parts would meet the minus 10% specification. At 4.8V (-4%) and -40°C, 80% of the units shipped to date would pass. The data presented in this memo is from a small sample size and could improve or get worse.
For additional information please contact myself (719) 594-8252 or Tim Meade (719) 594-8048.
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