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108048/8748/8035L
CRYSTAL OSCILLATOR MODE
0-15
pF
(INCLUDES XTAL
SOCKET, STRAy)
,---r----'-1
XTALl
1·6
mHz
'-----t------"l3
XTAL2
15-25
pF
(INCLUDES SOCKET, I
STRAY)
-=-
CRYSTAL SERIES RESISTANCE SHOULD
BE
<751'1
AT
6 MHz; <180Q AT
3.8
MHz.
DRIVING FROM EXTERNAL SOURCE
+5V
4701'1
}>--+----"-t
XTALl
+5V
4701'1
L-_--+-_-"-j
XT
AL2
BOTH
Xl
AND
X2
SHOULD
BE
DRIVEN.
RESISTORS
TO
Vee ARE NEEDED
TO
ENSURE
V,H
=
3.BV
IF TTL CIRCUITRY IS
USED. THE MINIMUM HIGH AND THE MINIMUM LOW TIMES ARE 45%.
LC
OSCILLATOR MODE
-"-
~
NOMINALf
45
flH
20
pF
5.2
MHz
120
J.lH
20
pF
3.2 MHz
...--..--"'1XTALl
C,=C+3Cpp
2
'----+--"'1XTAL2
Cpp:::::
5-10
pF
PIN·TO·PIN
CAPACITANCE
EACH C
SHOULD
BE
APPROXIMATELY
20
pF,lNCLUDING STRAY CAPACITANCE.
PROGRAMMING, VERIFYING, AND
ERASING THE 8748 EPROM
Programming Verification
In brief, the programming process consists of: activat-
ing 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 following is a
list
of the pins used
for
program-
ming and a description
of
their functions:
Pin
Function
XTAL1 Clock Input
(1
to
6 MHz)
RESET
Initialization and Address Latching
TEST 0
Selection
of
Program
or
Verify Mode
EA
Activation of ProgramlVerify Modes
BUS
Address and Data Input
Data Output during Verify
P20-1
Address Input
Voo
Programming Power
Supply
PROG
Program Pulse Input
6-24
WARNING:
An
attempt
to
program a mis-socketed 8748 will result in
severe damage
to
the part. An indication
of
a properly
socketed part is the appearance
of
the ALE
clock
out-
put. The lack
of
this
clock
may
be
used
to
disable the
programmer.
The ProgramlVerify Sequence is:
1.
Voo=5V,
clock
applied
or
internal oscillator oper-
ating, RESET=OV, TEST
0=5V,
EA=5V,
BUS
and
PROG
floating:
2.
Insert 8748 in programming socket.
3.
TEST
0 =
OV
(select program mode).
4.
EA
=
23V
(activate program mode).
5.
Address applied to
BUS
and
P20-1.
6.
RESET
=
5V
(latch address).
7.
Data applied to BUS.
8.
Voo =
25V
(programming power).
9.
PROG
=
OV
followed by one
50
ms pulse
to
23
V.
10.
Voo=5V.
11.
TEST 0 =
5V
(verify mode).
12.
Read
and verify data on
BUS.
13.
TEST
0 =
OV.
14.
RESET
=
OV
and repeat from step
5.
15.
Programmer should be at conditions of step 1 when
8748 is removed from socket.
AFN-008eOA-Q7