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GENERAL DESCRIPTION
The DS1553 is a full-function, year-2000-compliant
(Y2KC) real-time clock/calendar (RTC) with an RTC
alarm, watchdog timer, power-on reset, battery
monitor, and 8k x 8 nonvolatile static RAM. User
access to all registers within the DS1553 is
accomplished with a bytewide interface as shown in
Figure 1. The RTC registers contain century, year,
month, date, day, hours, minutes, and seconds data in
24-hour BCD format. Corrections for day of month and
leap year are made automatically.
ORDERING INFORMATION
*PowerCap required, must be ordered separately.
FEATURES
§ Integrated NV SRAM, RTC, Crystal, Power-Fail
Control Circuit, and Lithium Energy Source
§ Clock Registers are Accessed Identically to the
Static RAM; These Registers are Resident in the 16
Top RAM Locations
§ Totally Nonvolatile with Over 10 Years of
Operation in the Absence of Power
§ Precision Power-On Reset
§ Programmable Watchdog Timer and RTC Alarm
§ BCD-Coded Year, Month, Date, Day, Hours,
Minutes, and Seconds with Automatic Leap Year
Compensation Valid Up to the Year 2100
§ Battery Voltage Level Indicator Flag
§ Power-Fail Write Protection Allows for ±10% VCC
Power-Supply Tolerance
§ Lithium Energy Source is Electrically
Disconnected to Retain Freshness Until Power is
Applied for the First Time
PIN CONFIGURATIONS
PART PIN-PACKAGE VCC (V) TOP MARK
DS1553-100 28 EDIP 5.0 DS1553-100
DS1553-70 28 EDIP 5.0 DS1553-070
DS1553P-100 34 PowerCap® 5.0 DS1553P-100
DS1553P-70 34 PowerCap 5.0 DS1553P-70
DS1553W-120 28 EDIP 3.3 DS1553W-120
DS1553W-150 28 EDIP 3.3 DS1553W-150
DS1553WP-120 34 PowerCap 3.3 DS1553WP-120
DS1553WP-150 34 PowerCap 3.3 DS1553WP-150
DS9034PCX* — — DS9034PCX
DS1553
64kB, Nonvolatile, Year-2000-Compliant
Timekeeping RAM
www.maxim-ic.com
PowerCap is a registered trademark of Dallas Semiconductor.
1
IR
FT
2
3
N.C.
N.C.
RS
VCC
W
O
C
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
4
5
6
7
8
9
10
11
12
13
14
15
16
17
N.C.
N.C.
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
N.C.
12
11
10
9
8
7
6
5
4
3
2
1
0
34 N.C.
X1 GND VBAT X2
34-Pin PowerCap Module Board
(Uses DS9034PCX PowerCap)
DS1553
28-Pin Encapsulated Package
(700-mil Extended)
VCC
R
/FT
8
9
11
10
DQ7
DQ6
DQ5
DQ4
DQ3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
RS
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS1553
TOP VIEW