DS1556 Datasheet, PDF (1/20 Pages) Dallas Semiconductor – 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM

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DS1556
1M, Nonvolatile, Y2K-Compliant
Timekeeping RAM
FEATURES
§ Integrated NV SRAM, Real-Time Clock
(RTC), Crystal, Power-Fail Control Circuit,
and Lithium Energy Source
§ Clock Registers are Accessed Identically to
the Static RAM; These Registers Reside in
the 16 Top RAM Locations
§ Century Byte Register (i.e., Y2K Compliant)
§ 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%
V_CC Power-Supply Tolerance
§ Lithium Energy Source is Electrically
Disconnected to Retain Freshness Until
Power is Applied for the First Time
§ Also Available in Industrial Temperature
Range: -40°C to +85°C
PIN CONFIGURATIONS
TOP VIEW
RST
A16
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
32
2 _{SemiDcaolnladsuctor}³¹
3 DS1556 30
4
29
5
28
6
27
7
26
8
25
9
24
10
23
11
22
12
21
13
20
14
19
15
18
16
17
VCC
A15
IRQ/FT
WE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
Encapsulated DIP
IRQ/FT 1
A15 2
A16 3
Dallas
Semiconductor
34
33
32
RST 4
DS1556
31
VCC
WE
5
6
30
29
OE
CE
DQ7
7
8
9
DQ6 ¹⁰
DQ5 ¹¹
28
27
26
25
24
DQ4 12
23
DQ3 ¹³
22
DQ2
DQ1
DQ0
GND
14
21
15
20
16
19
17
X1 GND V_BAT X2
18
N.C.
N.C.
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
PowerCap^® Module Board
(Uses DS9034PCX PowerCap)
PowerCap is a registered trademark of Dallas Semiconductor.
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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REV: 101804