DS12R885-5 MAXIM [Maxim Integrated Products], DS12R885-5 Datasheet - Page 14

• Manufacturer Part Number: DS12R885-5
• Description: RTC with Constant-Voltage Trickle Charger
• Manufacturer: MAXIM [Maxim Integrated Products]

RTC with Constant-Voltage Trickle Charger
The three alarm bytes can be used in two ways. First,
when the alarm time is written in the appropriate hours,
minutes, and seconds alarm locations, the alarm inter-
rupt is initiated at the specified time each day, if the
alarm-enable bit is high. In this mode, the “0” bits in the
alarm registers and the corresponding time registers
must always be written to 0
the 0 bits in the alarm and/or time registers to 1 can
result in undefined operation.
The second use condition is to insert a “don’t care”
state in one or more of the three alarm bytes. The don’t-
care code is any hexadecimal value from C0 to FF. The
two most significant bits of each byte set the don’t-care
Table
X = Read/Write Bit.
Note: Unless otherwise specified, the state of the registers is not defined when power is first applied. Except for the seconds regis-
ter, 0 bits in the time and date registers can be written to 1, but may be modified when the clock updates. 0 bits should always be
written to 0 except for alarm mask bits.
14
ADDRESS
0EH-7F
0AH
0BH
0CH
0DH
00H
01H
02H
03H
04H
05H
06H
07H
08H
09H
____________________________________________________________________
2A. Time, Calendar, and Alarm Data Modes—BCD Mode (DM = 0)
AM/PM
AM/PM
BIT 7
IRQF
VRT
SET
UIP
0
0
0
0
0
0
0
0
0
X
BIT 6
DV2
PIE
PF
0
0
0
0
0
0
X
10 Years
(Table
10 Seconds
10 Seconds
10 Minutes
10 Minutes
BIT 5
DV1
AIE
AF
0
0
0
0
0
X
10 Hours
10 Hours
10 Date
2A and 2B). Writing
10 Months
10 Hours
10 Hours
BIT 4
DV0
UIE
UF
X
0
0
SQWE
BIT 3
RS3
0
0
0
X
BIT 2
RS2
DM
condition when at logic 1. An alarm is generated each
hour when the don’t-care bits are set in the hours byte.
Similarly, an alarm is generated every minute with
don’t-care codes in the hours and minute alarm bytes.
The don’t-care codes in all three alarm bytes create an
interrupt every second.
All 128 bytes can be directly written or read, except for
the following:
Seconds
Seconds
1) Registers C and D are read-only.
2) Bit 7 of register A is read-only.
3) The MSB of the seconds byte is read-only.
X
0
0
Minutes
Minutes
Month
Hours
Hours
Date
Year
24/12
BIT 1
RS1
Day
0
0
X
BIT 0
DSE
RS0
X
0
0
Seconds Alarm
Minutes Alarm
Hours Alarm
FUNCTION
Seconds
Minutes
Control
Control
Control
Control
Month
Hours
RAM
Date
Year
Day
1–12 +AM/PM
1–12 +AM/PM
RANGE
00–59
00–59
00–59
00–59
00–23
00–23
01–07
01–31
01–12
00–99
—
—
—
—
—