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. The real time clock information resides in the eight uppermost RAM locations. The RTC registers contain year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the day of the month and leap year are made automatically. The RTC clock registers are double-buffered to avoid access
of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1644 also contains its own power-fail circuitry, which deselects the device when the VCC supply is in an out-of-tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.
*DS9034-PCX, DS9034I-PCX, DS9034-PCX+ required (must be ordered separately).
A "+" indicates a lead-free product. The top mark will include a "+" symbol on lead-free devices.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.
Devices:
1-5 of 5
DS1644
Notes
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Status
Package:
TYPE PINS FOOTPRINT
DRAWING CODE/VAR *
Temp
RoHS/Lead-Free? Materials Analysis
DS1644L-120
N/A
No Longer Available
Land Pattern: Not Available
0°C to +70°C
See data sheet
DS1644-120
120ns
Active
EDIP;28 pin;630 mm²
Outline Drawing: 21-0245 (PDF)
Land Pattern: Not Available
Use pkgcode/variation: MDF28-5*
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