Intel MCS48 User Manual page 159

8048/8648/8748/8035
CRYSTAL OSCILLATOR
MODE
DRIVING
FROM
EXTERNAL SOURCE
0—
15
pF
(INCLUDES XTAL
SOCKET, STRAY)
-o
15-25
pF
(INCLUDES SOCKET,
STRAY)
-±-
CRYSTAL
SERIES RESISTANCE
SHOULD
BE <752 AT
6
MHz; <180O
AT
3.6
MHz.
BOTH
X1
AND
X2
SHOULD
BE DRIVEN.
RESISTORS TO V
Cc
ARE NEEDED TO ENSURE V
fH
=
3.8V IF
TTL CIRCUITRY
IS
USED.
THE MINIMUM HIGH
AND THE MINIMUM LOW
TIMES ARE 45%.
LC
OSCILLATOR
MODE
45
M
H
20 pF
5.2
MHz
120
uH
20
pF
3.2
MHz
C'
=
C
+ 3Cpp
C
PP =
5-
10
pF
PIN-TO-PIN
CAPACITANCE
EACH
C
SHOULD
BE APPROXIMATELY
20
pF,
INCLUDING
STRAY
CAPACITANCE.
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
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
XTAL1
Clock
Input
(1
to6MHz)
Reset Initialization
and Address
Latching
TestO
Selection of
Program or Verify
Mode
EA
Activation of
Program/Verify
Modes
BUS
Address and Data Input
Data Output
During Verify
P20-1 Address Input
Vdd Programming Power Supply
PROG
Program
Pulse Input
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 programmer.
The Program/Verify sequence
is:
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
1CLD.
:
5v, Clock applied or
internal oscillator
operating.
RESET
=
Ov,
TEST
=
5v,
EA
=
5v,
BUS
and
PROG
floating.
Insert
8748
in
programming
socket
TEST
= Ov
(select
program mode)
EA
= 23 v
(activate
program mode)
Address
applied to
BUS
and P20-1
RESET = 5v
(latch address)
Data applied
to
BUS
Vqq
= 25v (programming power)
PROG
=
Ov followed by one
50ms
pulse
to
23V
V
DD
5v
TEST
= 5v
(verify
mode)
Read and
verify
data
on
BUS
TEST
= Ov
RESET
= Ov
and repeat
from
step 5
Programmer
should be
at
conditions
of step
1
when 8748
is
removed from
socket.
6-7