Rainbow Electronics DS12887A User Manual
Features, Pin assignment (top view), Pin description
1 of 2
073102
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FEATURES
§ Drop-in replacement for IBM AT computer
clock/calendar
§ Pin compatible with the MC146818B and
DS1287A
§ Totally nonvolatile with over 10 years of
operation in the absence of power
§ Self-contained subsystem includes lithium,
quartz, and support circuitry
§ Counts seconds, minutes, hours, days, day of
the week, date, month, and year with leap-
year compensation valid up to 2100
§ Binary or BCD representation of time,
calendar, and alarm
§ 12-hour or 24-hour clock with AM and PM
in 12-hour mode
§ Daylight Savings Time option
§ Selectable between Motorola and Intel bus
timing
§ Multiplex bus for pin efficiency
§ Interfaced with software as 128 RAM
locations
– 14 bytes of clock and control registers
– 114 bytes of general-purpose RAM
§ Programmable square-wave output signal
§ Bus-compatible interrupt signals (IRQ)
§ Three interrupts are separately software-
maskable and testable
– Time-of-day alarm once/second to
once/day
– Periodic rates from 122
ms to 500ms
– End-of-clock update cycle
§ Underwriters Laboratory (UL) recognized
PIN ASSIGNMENT (Top View)
Package Dimension Information
PIN DESCRIPTION
AD0–AD7 - Multiplexed Address/Data Bus
N.C.
- No Connect
MOT
- Bus Type Selection
CS
- RTC Chip-Select Input
AS
- Address Strobe
R/
W
- Read/Write Input
DS
- Data Strobe
RESET
- Reset Input
IRQ
- Interrupt Request Output
SQW
- Square-Wave Output
V
CC
- +5V Main Supply
RCLR
- RAM Clear
GND
- Ground
ORDERING INFORMATION
PART
PIN-PACKAGE TOP MARK
TEMP RANGE
DS12887A 24 PDIP Module
DS12887A
0°C to +70°C
MOT
1
2
3
4
5
6
7
8
9
10
11
12
23
N.C.
AD1
AD3
AD4
AD5
AD6
AD7
GND
V
CC
SQW
NC
N.C.
IRQ
RESET
DS
N.C.
R/W
AS
CS
24
22
21
20
19
18
17
16
15
14
13
N.C.
AD0
AD2
RCLR
DS12887A
Real-Time Clock
www.maxim-ic.com
www.maxim-ic.com