NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

NASA Test of Actel SX-A, SX-S and SX-SU FPGAs

t_PD Summary

The two charts below provide a summary of the mean propagation delay for each lot of parts in the NASA test of SX-A, SX-S, and SX-SU FPGAs.  Each lot of parts consists of 150 FPGAs.

All of these measurements are taken at laboratory temperature, which is not strictly controlled.  As a result, the data presented will have some temperature dependence in it which is not removed.  While the temperature coefficient, at approximately 0.15 %/°C to approximately 0.25 %/°C  is not insignificant, it is sufficiently small as to not be a factor in this assessment.  Note that our flight rules allow for a ±10% change in t_PD over the life of a mission.  The uncorrected measured data falls well within that range.  Margin for radiation has, of course, it's own derating tolerance.

These charts will be updated as new data sets are collected and analyzed.

Table 1.  Summary of device temperature exposures.  Each Step is 250 hours

Lot	Device Type	Step 1	Step 2	Step 3	Step 4	Step 5
KU1	RTSX32SU	125 °C	125 °C	-55 °C	125 °C	125 °C
KU2	RTSX32SU	125 °C	125 °C	125 °C	125 °C	-55 °C
KM1	RT54SX32S	125 °C	125 °C	125 °C	125 °C	-55 °C
KM2	RT54SX32S	125 °C	125 °C

Figure 1.  t_PHL vs. Test Step

Figure 2.  t_PLH vs. Test Step

Table 2.  Summary of standard deviation for t_PHL (ns).  Each Step is 250 hours

Table 3.  Summary of standard deviation for t_PLH (ns).  Each Step is 250 hours

Table 4.  Summary of t_PHL (ns).  Each Step is 250 hours

Table 5.  Summary of Delta t_PHL (ns).  Each Step is 250 hours

Table 6.  Summary of t_PLH (ns).  Each Step is 250 hours

Table 7.  Summary of Delta t_PLH (ns).  Each Step is 250 hours

NASA Independent Test of SX-A, SX-S, and SX-SU Home Page

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Last Revised: May 15, 2005
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