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3. Don't touch the socket adapter or chip while writing. Touching either of these can cause
contact faults and write errors.
17.3.3 Reliability of Written Data
An effective way to assure the data holding characteristics of the programmed chips is to bake
them at 150°C, then screen them for data errors. This procedure quickly eliminates chips with
PROM memory cells prone to early failure.
Figure 17-6 shows the recommended screening procedure.
Write program
Bake with power off
°
150
C 48 Hr
Read and check program
V
= 4.5V and 5.5V
CC
Install
Figure 17-6 Recommended Screening Procedure
If a series of write errors occur while the same PROM writer is in use, stop programming and
check the PROM writer and socket adapter for defects, using a microcomputer with a windowed
package and on-chip EPROM.
Please inform Hitachi of any abnormal conditions noted during programming or in screening of
program data after high-temperature baking.
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