DS1644L-120 Dallas Semiconductor, DS1644L-120 Datasheet
DS1644L-120
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DS1644L-120 Summary of contents
Page 1
... DESCRIPTION The DS1644L is a low profile module that requires a PLCC surface mountable socket and is functionally equivalent to the DS1644. The DS1644L 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 real time clock information resides in the eight upper- most RAM locations ...
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... However, the internal clock reg- isters of the double buffered system continue to update so that the clock accuracy is not affected by the access of data. All of the DS1644L registers are updated simul- taneously after the clock status is reset. Updating is within a second after the read bit is written to zero. ...
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... The eighth bit of the control register is the write bit. Set- ting the write bit to a one, like the read bit, halts updates to the DS1644L registers. The user can then load them with the correct day, date and time data in 24 hour BCD format ...
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... X = UNUSED WRITING DATA TO RAM OR CLOCK The DS1644L is in the write mode whenever WE and CE are in their active state. The start of a write is refer- enced to the latter occurring high to low transition CE. The addresses must be held valid throughout the after the last address cycle ...
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... CC sumed when V is returned to tions, the life expectancy of the DS1644L will be approx- CC imately equal to the shelf life (expected useful life of the lithium battery with no load attached) of the lithium bat- tery which may prove long as 20 years. ...
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... DS1644LPM ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability ...
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... 5.0V CC DS1644L–150 UNITS UNITS MIN MAX 150 ns 150 ns 150 120 150 120 150 110 MAX UNITS DS1644LPM 10%) NOTES NOTES NOTES 041697 7/11 ...
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... Fall Time (Min) V Rise Time (Min (Max Time Power–Up Expected Data Retention Time (Oscillator On) DS1644L READ CYCLE TIMING READ t RC A0–A14 t CEA CE t CEL t OEA OEL DQ0–DQ7 041697 8/11 SYMBOL MIN t ...
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... DS1644L WRITE CYCLE TIMING WRITE t WC A0–A14 CEW WEW WE t CEZ t DS VALID DQ0– OUT DQ7 POWER–DOWN/POWER–UP TIMING (MAX (MIN PFO BATT WRITE AH2 DH2 ...
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... Unencapsulatesd Low Profile Modules are not rec- ommended for processing through conventional wavesoldering techniques. The Use of a PLCC socket is recommended for production purposes. RECOMMENDED DS1644L MODULE SOCKET LAND PATTERNS 041697 10/11 OUTPUT LOAD EITHER A TWO OR FOUR SIDED SOCKET MAY BE UTILIZED FOR DS1644LPM INSTALLATION. ...
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... DS1644LPM 34–PIN LOW PROFILE MODULE E C NOTE: Please contact the factory for information on PLCC Sur- face mountable sockets PKG DIM MIN A 0.955 B 0.840 C 0.230 A D 0.975 E 0.047 F 0.015 F DS1644LPM INCHES MAX 0.980 0.855 0.250 0.995 0.053 0.025 041697 11/11 ...