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M80481
M87
481
M8035L
CRYSTAL OSCILLATOR MODE
Cl
~
1-_~
___
""'
___
2'-i
XTAL 1
,,::~:
=
-=-
I
1-_---'1
___
+-
__
...;3
1
XTAL2
C3
Cl
; SpF ± 12pF + STRAY < SpF
C2 ; CRYSTAL + STRAY < 8pF
C3
=
20pF
±
1pF
+ STRAY <
SpF
CRYSTAL SERIES RESISTANCE SHOULD BE LESS THAN 1SQ
AT
8MHz; LESS
THAN
180Q
AT
3.8MHz.
LCOSCILLATOR MODE
..h.
.£.
~
45
"H
20
pF
5.2 MHz
120
"H
20
pF
3.2
MHz
,---r---j
XTAU
'----4-_--j
XTAL2
c'= C + 3Cpp
2
Cpp
:::::
5 -
10
pF PIN·TO·PIN
CAPAC IT ANCE
EACH C
SHOULD
BE
APPROXIMATEl
Y 20 pF,
INCLUDING
STRAY
CAPACITANCE.
DRIVING FROM EXTERNAL SOURCE
+
SV
470Q
»---+-----'-1
XTAL1
+
SV
470Q
'---~--'-i
XTAL2
FOR
XTAL 1 AND XTAL 2 DEFINE
"HIGH"
AS VOLTAGES ABOVE 1.8V AND
"LOW"
AS VOLTAGES BELOW 1.6V. THE
DUTY
CYCLE REQUIREMENTS FOR EXTERNALLY
DRIVING XTAL
1 AND XTAL 2 USING THE CIRCUIT SHOWN ABOVE ARE AS
FOLLOWS:
FOR
THE 8048. XTAL 1 MUST BE HIGH 35-6S% OF THE PERIOD AND XTAL 2 MUST
PROGRAMMING, VERIFYING, AND
ERASING THE 8748 EPROM
Programming Verification
In
brief,
the
programming process consists of: activating
the
program mode, applying an address, latching
the
address, applying data, and appiying 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
XTALl
Reset
Test
0
EA
BUS
P20-1
Voo
PROG
Function
Clock Input
(1
to
6MHz)
Initialization and Address Latching
Selection
of
Program
or
Verify Mode
Activation
of
ProgramNerify
Modes
Address and Data
Input
Data
Output
During Verify
Address.
Input
Programming Power Supply
Program Pulse
Input
BE HIGH 3S-65% OF THE PERIOD.
FOR
THE 8748. XTAL MUST BE HIGH 45·50% OF THE PERIOD AND XTAL 2 MUST
BE HIGH
SO·SS%
OF THE PERIOD.
RISE
AND
FALL
TIMES MUST NOT EXCEED 20 ns.
WARNING:
An attempt
to
program a missocketed
8748
will
reSUlt
in
severe
damage
to
the part.
An
indication
of
a properly socketed
part
is
the
appearance
of
the
ALE
clock
output.
The lack
of
this clock may
be
used
to
disable the prQgrammer.
The
ProgramNerify
sequence
is:
1.
~
5v, Clock applied
or
internal oscillator operating,
RESET =
OIl,
TEST 0 = 5v,
EA
= 5v, 8US
and
PROG
floating.
6-28
2.
3.
4.
Insert 8748 in programming socket
TEST
0 =
Ov
(select program mode)
EA =
23V
(activate program mode)
5. Address applied
to
BUS
and
P2()'1
6. RESET = 5v (latch
address)
7.
Oata
appl
ied
to
BUS
8.
VOO=
25v (programming power)
9.
PROG =
011
followed
by
one
SOms
pulse
to
23V
10. VOO = 5v
11. TEST
0 = 5v (verify mode)
12.
Read
and verify data on BUS
13. TEST
0=
011
14. RESET =
011
and
repeat
from
step 5
15. Programmer should be
at
conditions
of
step 1 when 8748
is
removed from socket.
AFN-D076OAo02