SM8580 Nippon_Precision_Circuits America, SM8580 Datasheet - Page 14

• Manufacturer Part Number: SM8580
• Description: Real-time Clock ic
• Manufacturer: Nippon_Precision_Circuits America

Clock and Calendar Registers (Bank 0, Registers 0 to E)
Clock counters (registers 0 to 5)
I
FOS (oscillator failed detect bit (register 1, bit 3))
I
Day-of-week counter (register 6)
I
Calendar registers (registers 7 to E)
I
Data in these registers is interpreted in BCD for-
mat. For example, if the seconds registers 1 and 0
contain 0101 1001, then the contents are inter-
preted as the value 59 seconds.
The FOS bit is the oscillator failure flag. It indi-
cates that the oscillator has stopped due to supply
voltage reduction during operation. It is set to 1
when the oscillator stops, and remains 1 until reset
The day-of-week register contains values repre-
senting the day of the week as shown in the fol-
lowing table.
Registers B to E are 4 digits forming the western
calendar year.
Bank
Bank
Bank
0
0
0
Address
Address
Address
C
D
0
1
2
3
4
5
6
7
8
9
A
B
E
Day of week register
Second registers
Minute registers
Month registers
Hour registers
Date registers
Year registers
Register
Register
Register
SM8580AM
I
I
Hour register contents are values expressed in 24-
hour mode.
by writing 0 to FOS. It is not affected by the func-
tion of other bits. A 1 is written to FOS when
power is applied.
Leap-year adjustment is automatic for years 1901
to 2099.
Bit 2
0
0
0
0
1
1
1
TEST
Bit 3
Bit 3
Bit 3
FOS
800
80
8
8
8
8
8
8
Bit 1
NIPPON PRECISION CIRCUITS INC.—14
0
0
1
1
0
0
1
TEMP
Bit 2
Bit 2
Bit 2
400
40
40
40
4
4
4
4
4
4
4
Bit 0
0
1
0
1
0
1
0
2000
Bit 1
Bit 1
Bit 1
200
20
20
20
20
20
2
2
2
2
2
2
2
Wednesday
Weekday
Thursday
Saturday
Tuesday
Monday
Sunday
Friday
Bit 0
Bit 0
Bit 0
1000
100
10
10
10
10
10
10
1
1
1
1
1
1
1