
μ
PD78P4038Y
28
7. ERASURE CHARACTERISTICS (
μ
PD78P4038YKK-T ONLY)
Data written in the
μ
PD78P4038YKK-T program memory can be erased (FFH); therefore users can write other
data in the memory.
To erase the written data, expose the erasure window to light with a wavelength shorter than approx. 400 nm. Normally,
ultraviolet light with a wavelength of 254 nm is employed. The amount of light required to completely erase the data
is as follows:
Intensity of ultraviolet light
×
erasing time: 57.6 Ws/cm
2
min.
Erasing time: About 80 minutes (When using a 12,000
μ
W/cm
2
ultraviolet lamp. It may, however, take more time
due to lamp deterioration, dirt on the erasure window, or the like.)
The ultraviolet lamp should be placed within 2.5 cm from the erasure window during erasure. In addition, if a filter
is attached to the ultraviolet lamp, remove the filter before erasure.
8. PROTECTIVE FILM COVERING THE ERASURE WINDOW (
μ
PD78P4038YKK-T ONLY)
To prevent EPROM from being erased inadvertently by light other than that from the lamp used for erasing EPROM,
or to prevent the internal circuits other than EPROM from malfunctioning by light, stick a protective film on the erasure
window except when EPROM is to be erased.
9. QUALITY
The
μ
PD78P4038YKK-T is not intended for use in mass-produced products; they do not have reliability high enough
for such purposes. Their use should be restricted to functional evaluation in experiment or trial manufacture.
10. SCREENING ONE-TIME PROM PRODUCTS
NEC cannot execute a complete test of one-time PROM products (
μ
PD78P4038YGC-3B9,
μ
PD78P4038YGC-
8BT, and
μ
PD78P4038YGK-BE9) due to their structure before shipment. It is recommended that you screen (verify)
PROM products after writing necessary data into them and storing them at 125
°
C for 24 hours.