Dear customers,
About the change in the name such as "Oki Electric Industry Co. Ltd." and
"OKI" in documents to OKI Semiconductor Co., Ltd.
The semiconductor business of Oki Electric Industry Co., Ltd. was succeeded to OKI
Semiconductor Co., Ltd. on October 1, 2008.
Therefore, please accept that although
the terms and marks of "Oki Electric Industry Co., Ltd.", “Oki Electric”, and "OKI"
remain in the documents, they all have been changed to "OKI Semiconductor Co., Ltd.".
It is a change of the company name, the company trademark, and the logo, etc. , and
NOT a content change in documents.
October 1, 2008
OKI Semiconductor Co., Ltd.
550-1 Higashiasakawa-cho, Hachioji-shi, Tokyo 193-8550, Japan
http://www.okisemi.com/en/
¡ Semiconductor
MSM6542-01/02/03
MSM6542-01/02/03
DESCRIPTION
The MSM6542 is a perpetual-calendar-based
real time clock with an alarm function which
can read and write data in units of seconds. It
can be connected to various buses and can
function as a peripheral IC of a microcom-
puter.
The clock ranges are seconds, minutes, hours,
days, months, years, and days of the week.
The alarm ranges are seconds, minutes, hours,
days, months, and days of the week.
An event trigger is generated when the time
matches the specified time and an alarm oc-
curs or when the clock counter generates a
carry. The interrupt and pulse outputs are
provided for each of an alarm and a carry.
An interface with a microcomputer is imple-
mented by four data bus pins, four address
bus
¡ Semiconductor
REAL TIME CLOCK WITH PERIODIC AND ALARM OUTPUT
bus pins, three control bus pins, and two chip
select pins. These pins are used to write or
read data from the clock, alarm, and control
registers, or to modify the data.
The MSM6542 has an address latch enable
(ALE) input pin, allowing the data bus and
address bus to be shared. When the ALE
input pin is kept high, the data bus and ad-
dress bus can be exclusively used.
Other functions of the MSM6542 are: a 30-
second adjustment, stop and restart of clock,
data registers as RAM, and data register (RAM)
protection.
The CMOS circuitry used in the MSM6542
affords low power dissipation. The crystal
oscillator operates at 32.768 kHz. Provisions
for backup time keeping are included.
FEATURES
• Real time clock providing seconds, minutes,
hours, days, months, years, and days of
the week.
• Multiple alarm ranges covering seconds,
minutes, hours, days, months, and days of
the week. A desired alarm range can be
selected.
• A periodic interrupt output interval can
be selected over a wide range from 1/1024
seconds up to 10 minutes.
• Interface flexibility allows for connection
to many types of microprocessors.
• Single read-out procedure (Read flag).
• Single power sense circuitry. (Data protect
function).
• Unused registers can be used as RAM.
• 30-second adjustment by software or
hardware (software only for the MSM6542-
1/-2).
• Stop and restart of clock by software or
hardware (software only for the MSM6542-
1/-2).
68
• 1 Hz output for adjustment and check of
oscillation frequency (MSM6542-3 only).
• User selection of 12 or 24 hour clock mode.
• Address latch enable (ALE) input pin.
• Advanced CMOS circuitry allows low
stand-by voltage and current.
• User standard 32.768 kHz oscillator crys-
tal
• Available in multiple packages
18-pin plastic DIP (for the MSM6542-
1RS/2RS) (DIP18-P-300).
20-pin plastic SOP (for the MSM6542-
1MS-K/2MS-K) (SSOP20-P-250-K).
24-pin plastic DIP (for the MSM6542-
3RS) (DIP24-P-600).
24-pin plastic SOP (for the MSM6542-
3GS-VK) (SOP24-P-430-VK).
• Pin assignment compatibility with the
MSM6242BRS (The MSM6542-3MSK pro-
vides near compatibility.).
¡ Semiconductor
PIN CONFIGURATION
MSM6542-01/02/03
MSM6542-01RS
18-pin plastic DIP (top view)
INTERRUPT
OUT
CS
0
ALE
A
0
A
1
A
2
A
3
RD
V
SS
MSM6542-02RS
18-pin plastic DIP (top view)
INTERRUPT
OUT
CS
0
ALE
A
0
A
1
A
2
A
3
E
V
SS
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
V
DO
XT
XT
CS
1
D
0
D
1
D
2
D
3
WR
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
V
DO
XT
XT
CS
1
D
0
D
1
D
2
D
3
R/W
MSM6542-03RS
24-pin plastic DIP (top view)
PERIODIC
OUT
CS
0
ALARM OUT
ALE
A
0
30Sec. ADJ
A
1
68/80
A
2
A
3
(E) RD
V
SS
MSM6542-01MS-K
20-pin plastic SOP (top view)
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
V
DO
XT
XT
(NC)
STOP/START
CS
1
D
0
1Hz
D
1
D
2
D
3
WR
(R/W)
PERIODIC OUT
CS
0
ALARM OUT
ALE
A
0
30Sec. ADJ
A
1
68/80
A
2
A
3
(E) RD
V
SS
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
INTERRUPT OUT
1
CS
0
2
(NC)
3
ALE
4
A
0
5
A
1
6
A
2
7
A
3
8
RD
9
V
SS
10
20
19
18
17
16
15
14
13
12
11
V
DO
XT
XT
(NC)
CS
1
D
0
D
1
D
2
D
3
WR
MSM6542-03GS-VK
24-pin plastic SOP (top view)
MSM6542-02MS-K
20-pin plastic SOP (top view)
INTERRUPT OUT
1
CS
0
2
(NC)
3
ALE
4
A
0
5
A
1
6
A
2
7
A
3
8
E
9
V
SS
10
20
19
18
17
16
15
14
13
12
11
V
DO
XT
XT
(NC)
CS
1
D
0
D
1
D
2
D
3
R/
W
V
DO
XT
XT
(NC)
STOP/START
CS
1
D
0
1Hz
D
1
D
2
D
3
WR
(R/W)
NC : NO Connected (open)
69
70
R-
R-S
1
R-S
10
MI
1
R- R-
R-
MI
10
R-H
1
R-H
10
R-W R-D
1
R-D
10
MO
1
MO
10
R-Y
1
R-Y
10
COMPARATOR
A
L
A O
R U
M T
A-
A-S
1
A-S
10
MI
1
A-
A-
A-
MI
10
A-H
1
A-H
10
A-W A-D
1
A-D
10
MO
1
MO
10
INTERRUPT OUT
P
E
R
I O
O U
D T
I
C
C
C'
C
D'
C
E'
A-EN
ABLE
C
D
C
E
C
F
XT
RESET
STOP
32.768KHz
XT
OSC
Less-than-second
counter
MSM6542-01/02/03
Control
counter
D
3
D
2
D
1
D
0
D
A
T
A
I.
F.
WR
or R/W
R/W
RD
or E
(-1) (-2)
I
F
D.P.
A
3
FUNCTIONAL BLOCK DIAGRAM (MSM6542-01, 02)
A
2
A
1
A
0
D
E
C
O
D
E
R
R-S
I
to C
F
A-S
I
to C
E'
CS
0
A
D
D
R
E
S
S
I.
F.
BANK 1/0
ALE
¡ Semiconductor
CS
1
XT
RESET
STOP
1Hz
32.768KHz
¡ Semiconductor
XT
OSC
Less-than-second
counter
Control
counter
D
3
D
2
D
1
D
0
R-S
1
R-S
10
R-
MI
1
R-
R- R-
MI
10
R-H
1
R-H
10
R-W
R-D
1
R-D
10
MO
1
MO
10
R-Y
1
R-Y
10
D
A
T
A
I.
F.
R/W or
WR
COMPARATOR
R/W
A
L
A O
R U
M T
ALARM OUT
E or
RD
68/80
I
F
FUNCTIONAL BLOCK DIAGRAM (MSM6542-03)
D.P.
A-S
1
A-S
10
A-
MI
1
A
3
A-
A-
A-
MI
10
A-H
1
A-H
10
A-W
A-D
1
A-D
10
MO
1
MO
10
A
2
A
1
A
0
D
E
C
O
D
E
R
R-S
I
to C
F
A-S
I
to C
E'
PERIODIC OUT
CS
0
C
D
C
E
C
F
A
D
D
R
E
S
S
I.
F.
C
C'
BANK 1/0
C
D'
C
E'
A-EN
ABLE
P
E
R
I O
O U
T
D
I
C
ALE
CS
1
30sec. ADJ
MSM6542-01/02/03
STOP/START
71
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