DS14285 Datasheet, PDF (1/25 Pages) Dallas Semiconductor – Real Time Clock with NV RAM Control

www.dalsemi.com
DS14285/DS14287
Real Time Clock with NV RAM Control
FEATURES
Direct replacement for IBM AT computer
clock/calendar
Functionally compatible with the
DS1285/DS1287
Available as chip (DS14285, DS14285S, or
DS14285Q) or stand-alone module with
embedded lithium battery and crystal
(DS14287)
Automatic backup supply and write
protection to make external SRAM
nonvolatile
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- or 24-hour clock with AM and PM in
12-hour mode
Daylight Savings Time option
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 µs to 500 ms
– End of clock update cycle
Optional industrial temperature version
available DS14285 DIP, SOIC, and PLCC
PIN ASSIGNMENT
VCCO
1
X1 ₂
X2 3
AD0 4
AD1 5
AD2 6
AD3 7
AD4 8
AD5 9
AD6 10
AD7 11
GND 12
24 VCC
23 SQW
22 _CEO
21 CEI
20 VBAT
19 IRQ
18 RESET
17 DS
16 GND
15 R/W
14 ^AS
13 _CS
DS14285 24-Pin DIP
DS14285S 24-Pin SOIC
AD0
AD1
AD2
AD3
AD4
AD5
NC
4 3 2 1 28 27 26
5
25
6
24
7
23
8
22
9
21
10
20
11
19
12 13 14 15 16 17 18
CEI
VBAT
IRQ
RESET
DS
GND
R/W
DS14285Q 28-Pin PLCC
VCCO
1
NC ₂
NC 3
AD0 4
AD1 5
AD2 6
AD3 7
AD4 8
AD5 9
AD6 10
AD7 11
GND ¹²
24
VCC
23 SQW
22 CEO
21 CEI
20 ^NC
19 IRQ
18 RESET
17 DS
16 NC
15 R/W
14 ^AS
13 _CS
DS14287 24-Pin
Encapsulated Package
1 of 25
080400