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22.3 Erasure Characteristics (for µ PD78P014DW, 78P014YDW)
Through exposure to light having a very short wavelength of less than 400 nm, contents of the programmed data
can be erased (FFH).
The µ PD78P014DW and 78P014YDW program memory contents are usually erased by ultraviolet rays having
a wavelength of 254 nm. The amount of exposure needed to completely erase the µ PD78P014DW and 78P014YDW
is at least 15 W × s/cm
using a 12000 µ W/cm
as when there has been deterioration of ultraviolet ray lamp performance or when the erasure window is dirty. When
erasing, place the µ PD78P014DW and 78P014YDW within 2.5 cm of the ultraviolet ray lamp. If a filter has been
attached to the ultraviolet ray lamp, remove the filter before erasing.
22.4 Opaque Film on Erasure Window (for µ PD78P014DW, 78P014YDW)
When erasing EPROM contents, be sure to cover the erasure window with a shading film to prevent unintentional
erasure of EPROM contents by light source other than the ultraviolet ray lamp and to prevent a light source from
unintentionally affecting internal circuits other than the EPROM.
22.5 Screening of One-Time PROM Versions
Because of their construction, one-time PROM versions ( µ PD78P014CW, 78P014YCW, 78P014GC-AB8, 78P014YGC-
AB8) cannot be fully tested by NEC before shipment. After the necessary data has been written, it is recommended
that screening is implemented in which PROM verification is performed after high-temperature storage under the
following conditions.
www.DataSheet4U.com
NEC is offering one-time PROM writing to marking, screening and verifying with charge under the name QTOP
microcontroller. Please contact an NEC sales representative for the details.
CHAPTER 22 µ PD78P014, 78P014Y
(ultraviolet ray strength × erasure time). The erasure time is about 15 to 20 minutes (when
2
2
ultraviolet ray lamp). However, the required erasure time may be longer in some cases, such
Storage Temperature
125°C
Storage Time
24 hours
TM
501
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