
ACopyright 1995 by Dallas Semiconductor Corporation.
DS1385/DS1387
RAMified Real Time Clock 4K x 8
DS1385/DS1387
012496 1/20
FEATURES
Upgraded IBM AT computer clock/calendar with
4K x 8 extended RAM
Totally nonvolatile with over 10 years of operation in
the absence of power
Counts seconds, minutes, hours, day of the week,
date, month and year with leap year compensation
Binary or BCD representations 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 64 user RAM locations
plus 4K x 8 of static RAM
– 14–bytes of clock and control registers
– 50–bytes of general purpose RAM
– 4K x 8 SRAM accessible by using separate con-
trol pins
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
μ
s to 500 ms
– End–of–clock update cycle
Available as chip (DS1385 or DS1385S) or stand
alone module with embedded lithium battery and
crystal (DS1387)
ORDERING INFORMATION
DS1385
DS1385S
DS1387
RTC Chip; 24–pin DIP
RTC Chip; 28–pin SOIC
RTC Module; 24–pin DIP
PIN ASSIGNMENT
V
CC
SQW
AS0
AS1
NC
IRQ
WER
RD
NC
WR
ALE
CS
OER
NC
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
GND
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
V
CC
SQW
NC
AS0
AS1
V
BAT
IRQ
WER
RD
BGND
WR
ALE
CS
NC
OER
X1
X2
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
NC
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS1387 24–PIN
ENCAPSULATED PACKAGE
(740 MIL FLUSH)
DS1385S 28–PIN SOIC
(330 MIL)
V
CC
SQW
AS0
AS1
V
BAT
IRQ
WER
RD
GND
WR
ALE
CS
OER
X1
X2
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
GND
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
DS1385 24–PIN DIP
(600 MIL)