Reliability Of Programmed Data - Hitachi H8/3035 Series Hardware Manual

14.4 Reliability of Programmed Data

A highly effective way to improve data retention characteristics is to bake the programmed chips
at 150°C, then screen them for data errors. This procedure quickly eliminates chips with PROM
memory cells prone to early failure.
Figure 14-6 shows the recommended screening procedure.
Program chip and verify programmed data
Bake chip for 24 to 48 hours at
125°C to 150°C with power off
Read and check program
Install
Figure 14-6 Recommended Screening Procedure
If a series of programming errors occurs while the same PROM programmer is in use, stop
programming and check the PROM programmer and socket adapter for defects. Please inform
Hitachi of any abnormal conditions noted during or after programming or in screening of
program data after high-temperature baking.
When programming the H8/3035 with a PROM programmer, set the program address range to
H'00000 to H'3FFFF. Specify H'FF data for addresses H'40000 and above. If these addresses are
programmed by mistake, it may become impossible to program or verify the PROM data. The
same problem may occur if an attempt is made to program the chip in page programming mode
or option page programming mode.
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