Rainbow Electronics DS1286 - Manual

1 of 13 111999
FEATURES
Keeps track of hundredths of seconds,
seconds, minutes, hours, days, date of the
month, months, and years; valid leap year
compensation up to 2100
Watchdog timer restarts an out-of-control
processor
Alarm function schedules real time-related
activities
Embedded lithium energy cell maintains time,
watchdog, user RAM, and alarm information
Programmable interrupts and square wave
outputs maintain 28-pin JEDEC footprint
All registers are individually addressable via
the address and data bus
Accuracy is better than ±1 minute/month at
25°C
Greater than 10 years of timekeeping in the
absence of V
CC
50 bytes of user NV RAM
PIN ASSIGNMENT
PIN DESCRIPTION
INTA - Interrupt Output A (open drain)
INTB (INTB) - Interrupt Output B (open drain)
A0-A5 - Address Inputs
DQ0-DQ7 - Data Input/Output
CE - Chip Enable
OE - Output Enable
WE - Write Enable
V
CC
- +5 Volts
GND - Ground
NC - No Connection
SQW - Square Wave Output
DESCRIPTION
The DS1286 Watchdog Timekeeper is a self-contained real time clock, alarm, watchdog timer, and
interval timer in a 28-pin JEDEC DIP package. The DS1286 contains an embedded lithium energy source
and a quartz crystal which eliminates the need for any external circuitry. Data contained within 64 eight-
bit registers can be read or written in the same manner as bytewide static RAM. Data is maintained in the
Watchdog Timekeeper by intelligent control circuitry which detects the status of V
CC
and write protects
memory when V
CC
is out of tolerance. The lithium energy source can maintain data and real time for over
10 years in the absence of V
CC
. Watchdog Timekeeper information includes hundredths of seconds,
seconds, minutes, hours, day, date, month, and year. The date at the end of the month is automatically
DS1286
Watchdog Timekeeper
www.dalsemi.com
13
27
28-Pin Encapsulated Package
(720-Mil Flush)
NC
A5
A3
A2
A1
A0
DQ0
DQ1
GND
DQ2
V
CC
WE
INTB(INTB)
NC
NC
SQW
OE
NC
CE
DQ7
DQ6
DQ5
DQ3
DQ4
1
2
3
4
5
6
7
8
9
10
11
12
14
28
26
25
24
23
22
21
20
19
18
17
15
16
NC
NC
A4
INTA