DS1644 Maxim, DS1644 Datasheet
DS1644
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DS1644 Summary of contents
Page 1
... 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 ...
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... BAT DESCRIPTION The DS1644 is a 32k x 8 nonvolatile static RAM with a full function real time clock, which are both accessible in a byte-wide format. The nonvolatile timekeeping RAM is functionally equivalent to any JEDEC standard 32k x 8 SRAM. The device can also be easily substituted for ROM, EPROM and EEPROM, providing read/write nonvolatility and the addition of the real time clock function ...
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... CLOCK OPERATIONS—READING THE CLOCK While the double-buffered register structure reduces the chance of reading incorrect data, internal updates to the DS1644 clock registers should be halted before clock data is read to prevent reading of data in transition. However, halting the internal clock register updating process does not affect clock accuracy. ...
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... The MSB Bit, (B7) of the control register is the write bit. Setting the write bit 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 then transfers those values to the actual clock counters and allows normal operation to resume ...
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... WRITING DATA TO RAM OR CLOCK The DS1644 is in the write mode whenever referenced to the latter occurring high to low transition of throughout the cycle another read or write cycle ...
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... V level of the internal battery supply, power input is switched from the V clock activity, RAM, and clock data are maintained from the battery until V level. > 4.5 volts) the DS1644 can be accessed as described above with CC is below the power-fail point V CC signal ...
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... V 2 -0.3 IL SYMBOL MIN I CC1 I ) CC2 CC3 2 4 DS1644/DS1644P (Over the Operating Range) TYP MAX UNITS NOTES 5 +0 0.8 V (Over the Operating Range) TYP MAX UNITS NOTES 4.0 mA A +1 0 ...
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... MIN SYMBOL MIN Fall Time t 300 Rise Time REC DS1644/DS1644P (Over the Operating Range) TYP MAX UNITS NOTES ns 120 ns 120 100 ...
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... DS1644 READ CYCLE TIMING DS1644 WRITE CYCLE TIMING DS1644/DS1644P ...
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... POWER-DOWN/POWER-UP TIMING OUTPUT LOAD DS1644/DS1644P ...
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... RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 28 EDIP 34 PWRCP th week of 1992. going high. WE going high. CE PACKAGE CODE MDF28+3 PC2 DS1644/DS1644P Note DOCUMENT NO. 21-0245 21-0246 ...
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... DS1644 28-PIN PACKAGE DS1644P PKG 28-PIN DIM MIN MAX A IN. 1.470 1.490 MM 37.34 37.85 B IN. 0.715 0.740 MM 18.16 18.80 C IN. 0.335 0.365 MM 8.51 9.27 D IN. 0.075 0.105 MM 1.91 2.67 E IN. 0.015 0.030 MM 0.38 0.76 F IN. 0.140 0.180 MM 3.56 4.57 G IN. 0.090 0.110 MM 2.29 2.79 H IN. 0.590 0.630 MM 14.99 16.00 J IN. 0.010 0.018 MM 0.25 0.45 K IN. 0.015 0.025 MM 0.38 0.64 PKG INCHES ...
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... DS1644P WITH DS9034PCX ATTACHED RECOMMENDED POWERCAP MODULE LAND PATTERN PKG INCHES DIM MIN A 0.920 B 0.955 C 0.240 D 0.052 E 0.048 F 0.015 G 0.020 PKG INCHES DIM MIN DS1644/DS1644P NOM MAX 0.925 0.930 0.960 0.965 0.245 0.250 0.055 0.058 0.050 0.052 ...
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... © 2010 Maxim Integrated Products DESCRIPTION Maxim and the Dallas logo are registered trademarks of Maxim Integrated Products, Inc. DS1644/DS1644P PAGES CHANGED 1, 7 ...