FDC37C935-QS Standard Microsystems (SMSC), FDC37C935-QS Datasheet - Page 130

• Manufacturer Part Number: FDC37C935-QS
• Manufacturer: Standard Microsystems (SMSC)

Specifications of FDC37C935-QS

• Lead Free Status / RoHS Status: Supplier Unconfirmed

Update Cycle
An update cycle is executed once per second if
the SET bit in Register B is clear and the
DV0-DV2 divider is not clear. The SET bit in the
"1" state permits the program to initialize the
time and calendar bytes by stopping an existing
update and preventing a new one from
occurring.
The primary function of the update cycle is to
increment the seconds byte, check for overflow,
increment the minutes byte when appropriate
and so forth through to the year of the century
each
byte.
ADD
0
1
2
3
4
5
6
7
8
9
INPUT CLOCK
FREQUENCY
32.768 kHz
32.768 kHz
The
Register 0: Seconds
Register 1: Seconds Alarm
Register 2: Minutes
Register 3: Minutes Alarm
Register 4: Hours
Register 5: Hours Alarm
Register 6: Day of Week
Register 7: Day of Month
Register 8: Month
Register 9: Year
alarm
update
(12 hour mode)
(24 hour mode)
(12 hour mode)
(24 hour mode)
REGISTER FUNCTION
byte
cycle also compares
Table 57 - Time, Calendar and Alarm Bytes
UIP BIT
with
Table 58 - Update Cycle Time
1
0
the
130
UPDATE CYCLE TIME
corresponding time byte and issues an alarm if
a match or if a "don't care" code is present.
The length of an update cycle is shown in Table
58. During the update cycle the time, calendar
and alarm bytes are not accessible by the
processor program. If the processor reads these
locations before the update cycle is complete
the output will be undefined. The UIP (update in
progress) status bit is set during the interval.
When the UIP bit goes high, the update cycle
will begin 244 us later. Therefore, if a low is read
on the UIP bit the user has at least 244us before
time/calendar data will be changed.
1948 s
-
BCD RANGE
01-12 am
81-92 pm
01-12 am
81-92 pm
00-59
00-59
00-59
00-59
00-23
00-23
01-07
01-31
01-12
00-99
UPDATE CYCLE
MINIMUM TIME
BINARY RANGE
244 s
00-3B
00-3B
00-3B
00-3B
01-0C
81-8C
01-0C
81-8C
01-0C
-
00-17
00-17
01-07
01-1F
00-63