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FEATURES

 Integrated NV SRAM, Real-Time Clock,

Crystal, Power-Fail Control Circuit and

Lithium Energy Source

 Clock Registers are Accessed Identically to

the Static RAM. These Registers are

Resident in the Eight Top RAM Locations.

 Totally Nonvolatile with Over 10 Years of

Operation in the Absence of Power

 BCD-Coded Year, Month, Date, Day, Hours,

Minutes, and Seconds with Leap Year

Compensation Valid Up to 2100

 Power-Fail Write Protection Allows for

±10% V

Power Supply Tolerance

 DS1644 Only (DIP Module)

Upward Compatible with the DS1643

Timekeeping RAM to Achieve Higher

RAM Density

Standard JEDEC Bytewide 32k x 8 Static

RAM Pinout

 DS1644P Only (PowerCap Module Board)

Surface Mountable Package for Direct

Connection to PowerCap Containing

Battery and crystal

Replaceable Battery (PowerCap)

Power-Fail Output

Pin-for-Pin Compatible with Other Densities

of DS164XP Timekeeping RAM

Underwriters Laboratory (UL) Recognized

PIN CONFIGURATIONS

ORDERING INFORMATION

PART VOLTAGE (V) TEMP RANGE PIN-PACKAGE TOP MARK

DS1644-120+ 5.0 0°C to +70°C 32 EDIP (0.740a) DS1644+120

DS1644P-120+ 5.0 0°C to +70°C 34 PowerCap* DS1644P+120

*DS9034-PCX, DS9034I-PCX, DS9034-PCX+ required (must be ordered separately).

+Denotes a lead(Pb)-free/RoHS-compliant package. The top mark includes a “+” symbol on lead(Pb)-free devices.

DQ7

DQ6

DQ5

DQ4

DQ3

DQ2

DQ1

DQ0

GND

A14

A13

A12

A11

A10

X1 GND V

BAT

34-Pin PowerCap Module Board

(Uses DS9034PCX PowerCap)

28-Pin Encapsulated Package

(720-mil Extended)

DQ0

DQ1

GND

DQ2

A13

A11

A10

DQ7

DQ6

DQ5

DQ3

DQ4

A12

A14

DS1644/DS1644P

Nonvolatile Timekeeping RAM

www.maxim-ic.com

19-5203; Rev 4/10

Summary of content (14 pages)

PAGE 1
9-5203; Rev 4/10 DS1644/DS1644P Nonvolatile Timekeeping RAM www.maxim-ic.com FEATURES        PIN CONFIGURATIONS Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit and Lithium Energy Source Clock Registers are Accessed Identically to the Static RAM. These Registers are Resident in the Eight Top RAM Locations.
PAGE 2
DS1644/DS1644P PIN DESCRIPTION PDIP 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 - PIN PowerCap 32 30 25 24 23 22 21 20 19 18 16 15 14 17 13 12 11 10 9 8 28 7 29 27 26 31 6 5 4 1-3,33,34 NAME A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND DQ3 DQ4 DQ5 DQ6 DQ7 CE A10 OE A11 A9 A8 A13 WE VCC RST NC X1, X2, VBAT FUNCTION Address Input Data Input/Output Ground Data Input/Output Active Low Chip-Enable Input Address Input Active Low Output-Enable Input Address Input Active-Lo
PAGE 3
DS1644/DS1644P PACKAGES The DS1644 is available in two packages (28-pin DIP and 34-pin PowerCap module). The 28-pin DIP style module integrates the crystal, lithium energy source, and silicon all in one package. The 34-pin PowerCap Module Board is designed with contacts for connection to a separate PowerCap (DS9034PCX) that contains the crystal and battery. This design allows the PowerCap to be mounted on top of the DS1644P after the completion of the surface-mount process.
PAGE 4
DS1644/DS1644P SETTING THE CLOCK The MSB Bit, (B7) of the control register is the write bit. Setting the write bit to a 1, like the read bit, halts updates to the DS1644 registers. The user can then load them with the correct day, date and time data in 24-hour BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock counters and allows normal operation to resume. STOPPING AND STARTING THE CLOCK OSCILLATOR The clock oscillator may be stopped at any time.
PAGE 5
DS1644/DS1644P DS1644 REGISTER MAP—BANK1 Table 2 ADDRESS 7FFF 7FFE 7FFD 7FFC 7FFB 7FFA 7FF9 7FF8 B7 — X X X X X OSC W B6 — X X FT X — — R OSC = STOP BIT R = READ BIT W = WRITE BIT X = UNUSED B5 — X X — — — X DATA B4 B3 — — — — — — X X — — — — — — X X B2 — — — — — — — X B1 — — — — — — — X B0 — — — — — — — X FUNCTION Year Month Date Day Hour Minutes Seconds Control 00-99 01-12 01-31 01-07 00-23 00-59 00-59 A FT = FREQUENCY TEST Note: All indicated “X” bits are unused but must be set to “0” du
PAGE 6
DS1644/DS1644P DATA RETENTION MODE When VCC is within nominal limits (VCC > 4.5 volts) the DS1644 can be accessed as described above with read or write cycles. However, when VCC is below the power-fail point VPF (point at which write protection occurs) the internal clock registers and RAM are blocked from access. This is accomplished internally by inhibiting access via the CE signal.
PAGE 7
DS1644/DS1644P ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground……………………………………………..-0.3V to +6.0V Storage Temperature Range………………………………………………-40°C to +85°C, Noncondensing Operating Temperature Range…….................…….......……………………0°C to +70°C, Noncondensing Lead Temperature (soldering, 10s) ...................................................................................................+260°C Soldering Temperature (reflow, PowerCap package) .........................................
PAGE 8
DS1644/DS1644P AC ELECTRICAL CHARACTERISTICS PARAMETER Read Cycle Time Address Access Time CE Access Time CE Data Off Time Output Enable Access Time Output Enable Data Off Time Output Enable to DQ Low-Z CE to DQ Low-Z Output Hold from Address Write Cycle Time Address Setup Time CE Pulse Width Address Hold from End of Write Write Pulse Width WE Data Off Time WE or CE Inactive Time Data Setup Time Data Hold Time High (Over the Operating Range) SYMBOL tRC tAA tCEA tCEZ tOEA tOEZ tOEL tCEL tOH tWC tAS tCEW t
PAGE 9
DS1644/DS1644P DS1644 READ CYCLE TIMING DS1644 WRITE CYCLE TIMING 9 of 14
PAGE 10
DS1644/DS1644P POWER-DOWN/POWER-UP TIMING OUTPUT LOAD 10 of 14
PAGE 11
DS1644/DS1644P NOTES: 1. All voltages are referenced to ground. 2. Typical values are at 25C and nominal supplies. 3. Outputs are open. 4. Data retention time is at 25C and is calculated from the date code on the device package. The date code XXYY is the year followed by the week of the year in which the device was manufactured. For example, 9225 would mean the 25th week of 1992. 5. tAH1, tDH1 are measured from WE going high. 6. tAH2, tDH2 are measured from CE going high. 7.
PAGE 12
DS1644/DS1644P DS1644 28-PIN PACKAGE PKG DIM A IN. MM B IN. MM C IN. MM D IN. MM E IN. MM F IN. MM G IN. MM H IN. MM J IN. MM K IN. MM 28-PIN MIN 1.470 37.34 0.715 18.16 0.335 8.51 0.075 1.91 0.015 0.38 0.140 3.56 0.090 2.29 0.590 14.99 0.010 0.25 0.015 0.38 MAX 1.490 37.85 0.740 18.80 0.365 9.27 0.105 2.67 0.030 0.76 0.180 4.57 0.110 2.79 0.630 16.00 0.018 0.45 0.025 0.64 DS1644P PKG DIM A B C D E F G INCHES MIN 0.920 0.980 0.052 0.048 0.015 0.025 NOM 0.925 0.985 0.055 0.050 0.020 0.027 MAX 0.930 0.
PAGE 13
DS1644/DS1644P DS1644P WITH DS9034PCX ATTACHED PKG DIM A B C D E F G INCHES MIN 0.920 0.955 0.240 0.052 0.048 0.015 0.020 NOM 0.925 0.960 0.245 0.055 0.050 0.020 0.025 MAX 0.930 0.965 0.250 0.058 0.052 0.025 0.030 NOM 1.050 0.826 0.050 0.030 0.
PAGE 14
DS1644/DS1644P REVISION HISTORY REVISION DATE DESCRIPTION PAGES CHANGED 4/10 Removed the leaded parts from the Ordering Information table; moved the Operating Range table into the Absolute Maximum Ratings section, added the lead temperature, and changed the soldering temperature information. 1, 7 14 of 14 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.