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2708 FAMILY
A.C. WAVEFORMS
121
ADDRESSES
CS/WE
ADDRESSES
VALID
K
V
~---
teo
I'II---~
tOF
(4)
I----+--
tACC
(31-------1
toH
(a)
OUTPUT
_____
...:.:.HI:;;:G:.:.H,:,Z
____
-f+~H~+_~H++_t_<
~
HIGH
Z
VALID OUTPUT
~//
NOTES:
2.
ALL
TIMES SHOWN IN PARENTHESES
ARE
MINIMUM AND
ARE
NSEC
UNLESS OTHERWISE SPECIFIED.
3.
CS
MAY BE DELAYED
UP
TO tACC·tCO AFTER ADDRESSES
ARE
VALID
4.~1;7~~~~~I~~iri
~R'6::~'OR
ADDRESS CHANGE, WHICHEVER OCCURS
FIRST.
ERASURE CHARACTERISTICS
The erasure characteristics
of
the 2708 family are such
that
erasure begins
to
occur
when exposed
to
light with wave-
lengths
shorter
than
approximately 4000 Angstroms (A). It
should
be
noted
that
sunlight and certain types
of
fluores-
cent
lamps have wavelengths
in
the
3000-4000A
range.
Data show
that
constant
exposure
to
room level fluores-
cent
lighting
could
erase
the
typical device
in
approxi-
mately
3 years, while
it
would take approximately 1 week
to
cause erasure when exposed
to
direct sunlight.
If
the
2708
is
to
be exposed
to
these types of lighting conditions
for
extended
periods
of
time, opaque labels are available
from
Intel which should be placed over
the
2708 window
to
prevent unintentional erasure.
8-11
The recommended erasure procedure (see Data Catalog
PROM/ROM
Programming Instructions Section) for the
2708
family
is
exposure
to
shortwave ultraviolet light
which has a wavelength
of
2537
Angstroms (A). The inte-
grated dose
(j,e"
UV
intensity X exposure time) for erasure
should be a minimum
of
15
W-sec/cm
2
.
The
erasure time
with this dosage
is
approximately 15
to
20
minutes using an
ultraviolet
lamp with a 12000
/J.W/cm
2
power rating, The
device should be placed within 1 inch
of
the
lamp tubes
during erasure,
Some lamps have a filter on their tubes
which
should be removed before erasure,
AFN-01104A-04