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Real time clock module
OSC
32.768 KHZ
Read mode
Write mode
Switching characteristic
Register table
Block diagram
Supplement
16 KHz
2 KHz
32 Hz
8 KHz
1 KHz
16 Hz
4 KHz
512 Hz
8 KHz
256 Hz
4 Hz
128 Hz
2 Hz
64 Hz
64 Hz register / counter
64 Hz alarm. register
Sec. alarm. register
Min. alarm. register
Hour alarm. register
Day-of-week alarm. register
Day alarm. register
Control register A
Control register B
Sec. register / counter
Min. register / counter
Hour register / counter
Day-of-week register / counter
Day register / counter
Month register / counter
Year register / counter
1 Hz
1 Hz
H • START / STOP
Write
Read
Data bus
Bus interface circuit
I/01 to I/03
Address bus
A0 to A3
CS
OE
WE
IRQ
Address
OE
CS
DOUT
Data valid
tRC
tAA
tACS
tOH
tOHZ
tOHZ
tCHZ
tOE
tOLZ
tOH
VOL
VOL
VOL
VOL
OE
CS
DOUT
DIN
Address
tWC
tCW
tAW
tW-R
tAS
tOHZ
WE
tWP
tDW
tDH
Measuring condition
Input pulse level: 0.8 to 2.4V
Input rise time, fall time: 5 nsec.
IN/OUT timing pulse level: 1.5V
Out put load: 1 TTL Gate +100pF
Note: Do not enter erroneous data for clock. This may result in time keeping error.
Be sure to enter “O” to TEST bit.
∗1
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
b7
∗
Data
b6
1 Hz
b5
2 Hz
b4
4 Hz
b3
8 Hz
b2
16 Hz
b1
32 Hz
b0
64 Hz
10-sec. digit
10-min. digit
1-sec. digit
1-min. digit
1-hour digit
10-hour digit
∗
∗
∗
∗
∗
∗
∗
∗
10-day digit
10-month
digit
10-year digit
1 Hz
2 Hz
4 Hz
8 Hz
16 Hz
32 Hz
64 Hz
ENB
Carry
flag
RAM7
RAM6
RAM5
RAM4
TEST
∗1
30-sec.
adjustment
RESET
S.START
/STOP
Alarm
flag
Carry
interruption
enable
Alarm
interruption
enable
10-sec. digit
10-min. digit
10-hour digit
∗
10-day digit
Day-of-week digit
1-day digit
1-month digit
1-year digit
1-sec. digit
1-min. digit
1-hour digit
Day-of-week digit
1-day digit
Remarks
Counter
Alarm
register
Control
register
Bit name
∗ mark
10-hour digit (b5)
Under-sec.
counter
Under-sec.
alarm register
Sec.to year
Day of week
Description
Empty bit and unwriteable
Recognized as “0” while reading
Only for 24H mode
Read only (unwriteable)
Used as binary code data
Used as binary code data
Both counter and alarm register use BCD code
Coded data is used
EX: 0…Sunday
1…Monday
2…Tuesday
3…Wednesday
4…Thursday 5…Friday
6…Saturday
Item
Read cycle time
Address access time
Chip select access time
Output enable access time
Output hold time
Chip select / output set time
Output enable / output set time
Chip deselect / output floating
Output disable / output floating
Symbol
tRC
tAA
tACS
tOE
tOH
tCLZ
tOLZ
tCHZ
tOHZ
Min.
85
—
10
5
0
Max.
—
85
45
—
35
Unit
ns
Item
Write cycle time
Chip select time
Address valid time
Address setup time
Write pulse time
Address holding time
___
WE output floating
Input data set time
Input data hold time
Output disable / output floating
___
WE output set time
Symbol
tWC
tCW
tAW
tAS
tWP
tWR
tWHZ
tDW
tDH
tOHZ
tOW
Min.
85
75
0
60
10
0
40
0
5
Max.
—
35
—
35
—
Unit
ns