DS1744

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% V_CC 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 Batter (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


Pinout




Specifications

Voltage Range on Any Pin Relative to Ground...........................-0.3V to +6.0V
Operating Temperature Range...................................-40°C to +85°C
Storage Temperature Range.................................-40°C to +85°C
Soldering Temperature..................See IPC/JEDEC J-STD-020A (DIP Package) (Note 7)
 


Description

The DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/cal endar (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 V_CC supply is in an out-of-tolerance condition. This feature prevents loss of data from
unpredictable system operation brought on by low V_CC as errant access and update cycles are avoided.