DS1644

19-5203; Rev 4/10 DS1644/DS1644P Nonvolatile Timekeeping RAM www.maxim-ic.com 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% VCC 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 A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 VCC 27 WE 26 A13 25 A8 24 A9 23 A11 22 OE 21 A10 20 CE 19 DQ7 18 DQ6 17 DQ5 16 DQ4 15 DQ3 28-Pin Encapsulated Package (720-mil Extended) NC NC NC PFO VCC WE OE CE DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 X1 GND VBAT X2 17 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 34-Pin PowerCap Module Board (Uses DS9034P...