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8041
AJ8641AJ8741
A
CRYSTAL OSCILLATOR MODE
<
16
pF
(INCLUDES XTAL,
SOC~ET,
STRAY)
r-----
I
I
I
~
,..
I
I
I
L
____
_
16-26
pF
(INCLUDES SOCKET, I
STRAY)
':"
XTALI
3 XTAL2
CRYSTAL SERIES RESISTANCE SHOULD
BE
<75Q
AT
6 MHz; <180Q
AT
3.6
MHz.
DRIVING FROM EXTERNAL SOURCE
+5V
4702
Jo--+------=-l
XTALI
+5V
470Q
'---~---=-j
XTAL2
BOTH XTALI AND XTAL2 SHOULD
BE
DRIVEN.
RESISTORS
TO
Vee ARE NEEDED
TO
ENSURE
V,H
= 3.8V
IF TTL CIRCUITRY IS USED.
LC OSCILLATOR MODE
J,.
..Q.
NOMINAL I
45.H
20
pF
5.2
MHz
120.H
20
pF
3.2
MHz
.....---.----"-1 XTAL 1
'--
......
-~XTAL2
CPP"
5-10
pF PIN·TO·PIN
CAPACITANCE
EACH C SHOULD
BE
APPROXIMATELY
20
pF.INCLUDING STRAY CAPACITANCE.
PROGRAMMING, VERIFYING, AND
ERASING THE 8741A EPROM
Programming Verification
In brief, the programming
process
consists of: activating
the program mode,
applying
an
address,
latching the
address,
applying data,
and
applying a programming pulse.
Each
word
is
programmed completely before moving
on
to
the next
and
is
followed by a verification
step.
The
follow-
ing
is
a list
of
the pins
used
for programming
and
a descrip-
tion
of
their functions:
Pin
Function
XTAL
1
Clock Input
(1
to
6MHz)
Reset
Initialization
and
Address
Latching
Test
0 Selection
of
Program
or Verify Mode
EA Activation
of
Program/Verify
Modes
BUS
Addre~s
and
Data
Input
Data
Output During Verify
P20-1
Address Input
VOO
Programming Power Supply
PROG
Program
Pulse
Input
WARNING:
An
attempt
to
program a missocketed 8741 A will result
in
severe
damage
to
the
part.
An
indication
of
a properly
socketed
part
is
the
appearance
of
the SYNC clock
output.
The lack
of
this clock may
be
used
to
disable the programmer.
The Program/Verify
seqUef1ce
fs:
1.
Aa
=
av,
CS
= SV,
EA
= SV, RESET =
av,
TESTa = SV,
Voo
=
5V,
clock
applied
or
internal
oscillator
operating,
BUS and PROG floating.
2.
Insert
8741A
in programming socket
3. TEST a =
Ov
(select program mode)
4.
EA
=
23V
(activate program mode)
S.
Address applied
to
BUS and
P2Q..1
6. RESET =
Sv
(latch address)
7.
Data
applied
to
BUS
8. V
DO
= 2Sv (programm ing power)
9.
PROG =
Ov
followed
by
one
sOms
pulse
to
23V
10_
VOO
= 5v
11. TEST 0 =
Sv
(verify mode)
12.
Read
and verify data on BUS
13. TEST 0 =
Ov
14.
RESET
=
Ov
and repeat
from
step S
16. Programmer should
be
at conditions
of
step 1 when
8741A
is
removed
from
socket.
9·130
00188A