DS1744P

Y2K-Compliant, Nonvolatile Timekeeping RAMs


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Description

The DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 32k x 8 NV SRAM. User access to all registers within the DS1744 is accomplished with a byte-wide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the date of each 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 DS1744 also contains its own power-fail circuitry that 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.
DS1744, DS1744P: Block Diagram DS1744, DS1744P: Block Diagram Enlarge+

Key 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.
  • Century Byte Register (i.e., Y2K Compliant)
  • Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
  • BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap-Year Compensation Valid Up to the Year 2100
  • Battery Voltage-Level Indicator Flag
  • Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance
  • Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time
  • DIP Module Only
    • Standard JEDEC Byte-Wide 32k x 8 Static RAM Pinout
  • PowerCap Module Board Only
    • Surface-Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal
    • Replaceable Battery (PowerCap)
    • Power-On Reset Output
    • Pin-for-Pin Compatible with Other Densities of DS174xP Timekeeping RAM
  • Also Available in Industrial Temperature Range: -40°C to +85°C

See parametric specs for Timekeeping & Real-Time Clocks (78)


Part NumberInterfaceVSUPPLY
(V)
Memory TypeMemory Size
(Bytes)
Time of Day AlarmsFunctionsPackage/PinsBudgetary
Price
See Notes
DS1744 Bytewide
3.3
5
NV SRAM32K0RTC
MOD/28
PWRCP/34
$17.03 @1k

Pricing 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 and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: DS1744P.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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Related Resources


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