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DS1385 Datasheet, PDF (1/20 Pages) Dallas Semiconductor – RAMified Real Time Clock 4K x 8
DS1385/DS1387
DS1385/DS1387
RAMified Real Time Clock 4K x 8
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 µs 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
RTC Chip; 24–pin DIP
DS1385S
RTC Chip; 28–pin SOIC
DS1387
RTC Module; 24–pin DIP
PIN ASSIGNMENT
OER 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 AS0
21 AS1
20 VBAT
19 IRQ
18 WER
17 RD
16 GND
15 WR
14 ALE
13 CS
DS1385 24–PIN DIP
(600 MIL)
OER 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 AS0
21 AS1
20 NC
19 IRQ
18 WER
17 RD
16 NC
15 WR
14 ALE
13 CS
DS1387 24–PIN
ENCAPSULATED PACKAGE
(740 MIL FLUSH)
OER
X1
X2
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
NC
GND
1
28
VCC
2
27
SQW
3
26
NC
4
25
AS0
5
24
AS1
6
23
VBAT
7
22
IRQ
8
21
WER
9
20
RD
10
19
BGND
11
18
WR
12
17
ALE
13
16
CS
14
15
NC
DS1385S 28–PIN SOIC
(330 MIL)
ECopyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
012496 1/20
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