Intel MCS48 User Manual page 411

8041 A/8741
A
8741
A
Erasure Characteristics
The
erasure
characteristics of the 8741
A
are
such
that
erasure begins
to
occur
when
exposed
to
light
with
wavelengths
shorter than approximately
4000 Ang-
stroms
(A).
It
should be noted
that sunlight
and
certain
types of fluorescent
lamps
have wavelengths
in
the
3000-4000A
range. Data
show
that
constant exposure
to
room
level
fluorescent lighting could erase the
typical
8741
A
in
approximately 3 years while
it
would
take
ap-
proximately
one week
to
cause
erasure
when
exposed
to direct sunlight.
If
the 8741
A
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 8741
A
window
to
prevent
unintentional erasure.
The
recommended
erasure procedure
for
the 8741
is
exposure
to
shortwave
ultraviolet
light
which has a
wavelength
of
2537
A.
The
integrated
dose
(i.e.,
UV
inten-
sity
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 12,000 /M//cm
2
power
rating.
The
8741
A
should be placed within
one
inch
of
the
lamp
tubes
dur-
ing erasure.
Some
lamps have
a
filter
on
their
tubes
which should be removed
before erasure.
A.C.
TIMING SPECIFICATION
FOR PROGRAMMING
T
A
= 25°C ±5°C, V
cc
= 5V
±5%,
V
DD
= 25V ±
1V
Symbol
Parameter
Min.
Max.
Unit
Test Conditions
tAW Address Setup
Time
to
RESET
t
4tcy
tWA Address Hold Time
After
RESET
i
4tcy
tDW Data
in
Setup Time
to
PROG
l
4tcy
tWD
Data
in
Hold
Time
After
PROG
1
4tcy
tPH
RESET
Hold Time
to Verify
4tcy
tvDDW Vdd
4tcy
tVDDH Vdd Hold Time
After
PROG
1
tPW Program
Pulse Width
50
60
MS
tTW Test Setup Time
for
Program
Mode
4tcy
tWT Test
Hold
Time
After
Program
Mode
4tcy
tDO
Test
to
Data Out
Delay
4tcy
tww
RESET
Pulse
Width
to Latch
Address
4tcy
tr, tf
Vdd and
PROG
Rise
and
Fall
Times
0.5
2.0
MS
tCY
CPU
Operation Cycle Time
5.0
MS
tRE
RESET
Setup
Time
Before
EA
1
4tcy
Note:
If
TEST
is
high,
t DO
can be
triggered by
RESET
1.
D.C.
SPECIFICATION
FOR
PROGRAMMING
T
A
= 25°C ±5°C, V
cc
=
5V
±5%,
V
DD
=
25V ±
1V
Symbol
Parameter
Min. Max.
Unit Test Conditions
Vdoh Vdd Program
Voltage High
Level
24.0
26.0
V
Vddl Vdd
Voltage
Low
Level
4.75 5.25 V
Vph
PROG
Program
Voltage
High
Level
21.5 24.5
V
VPL
PROG
Voltage
Low
Level
0.2 V
Veah
EA
Program
or Verify Voltage High
Level 21.5
24.5
V
Veal
EA
Voltage
Low
Level
5.25
V
Idd
Vdd High Voltage Supply Current
30.0
mA
IPROG
PROG
High Voltage Supply Current
16.0
mA
lEA
EA
High Voltage Supply Current
1.0
mA
8-121
001
88A