HD404669 Datasheet, PDF (112/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
• Check that the socket adapter is firmly mounted on the PROM programmer.
• Do not touch the socket adapter or the LSI during the programming. Touching them may affect the
quality of the contacts, which will cause programming errors.
PROM Reliability after Programming: In general, semiconductor devices retain their reliability,
provided that some initial defects can be excluded. These initial defects can be detected and rejected by
screening. Baking devices under high-temperature conditions is one method of screening that can rapidly
eliminate data-hold defects in memory cells. (Refer to the previous Principles of Programming/Erasure
section.)
ZTAT^TM microcomputer devices are extremely reliable because they have been subjected to such a
screening method during the wafer fabrication process, but Hitachi recommends that each device be
exposed to 150°C at one atmosphere after it is programmed, to ensure its best performance. The
recommended screening procedure is shown in figure 84.
Write the program data and
verify the values written
Expose to high temperature, without power
150°C ± 10°C, 48 h ^{+8 h *}
–0 h
Program read check
V_CC = 4.5 V or 5.5 V
Note: * Exposure time is measured from when the temperature in the heater reaches 150°C.
Figure 84 Recommended Screening Procedure
Note:
If programming errors occur continuously during PROM programming, suspend programming and
check for problems in the PROM programmer or socket adapter, using a windowed-package
microcomputer with on-chip EPROM, etc. ..... If programming verification indicates errors in
programming or after high-temperature exposure, please inform Hitachi.
Write rate: A write rate of 95% or above is guaranteed.
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