The DS1647 is a 512k 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 512k 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 DS1647 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.
Key Features
Integrates 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 Through 2099
Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance
DS1647 Only (DIP Module):
Standard JEDEC Byte-Wide 128k x 8 RAM Pinout
DS1647P 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
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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