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Data Sheet

FULL DATA SHEET (PDF, 320kB) Download   E-Mail

Description

The DS1643 is an 8K x 8 nonvolatile static RAM with a full function Real Time Clock (RTC) that are both accessible in a byte-wide format. The nonvolatile timekeeping RAM is functionally equivalent to any JEDEC standard 8K x 8 SRAM. The device can also be easily substituted in ROM, EPROM and EEPROM sockets 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 DS1643 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

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 Reside in the Eight Top RAM Locations. Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power Access Times of 70ns and 100ns BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Leap Year Compensation Valid Up to 2100 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 DS1643 Only (DIP Module) Standard JEDEC Byte-Wide 8K x 8 RAM Pinout UL Recognized DS1643P 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

Application Notes

Application Note 504: Design Considerations for Dallas Semiconductor Real-Time Clocks - DS1643 Application Note 507: PowerCap Package Allows for Density Upgrades, Surface Mount Assembly - DS1643, DS1643 Application Note 519: Using a Nonvolatile Timekeeping RAM with a Microcontroller - DS1643

Evaluation Kits

none

Design Guides

REAL-TIME CLOCKS (PDF)

Reliability Reports

Reliability Report: DS1643.pdf DS1643P.pdf

Software/Models

none

Ordering Information
Notes: Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions. * 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: 1-6 of 6
DS1643	Free Sample	Buy	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS1643-85+			MOD;28 pin;630 mm² Dwg: 56-G0002-001A (PDF) Use pkgcode/variation: MDF28+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1643-100			MOD;28 pin;630 mm² Dwg: 56-G0002-001A (PDF) Use pkgcode/variation: MDF28-2*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS1643-100+			MOD;28 pin;630 mm² Dwg: 56-G0002-001A (PDF) Use pkgcode/variation: MDF28+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1643P	Free Sample	Buy	Package: TYPE PINS FOOTPRINT   DRAWING CODE/VAR *	Temp	RoHS/Lead-Free? Materials Analysis
DS1643P-85+			PWRCP;34 pin;607 mm² Dwg: 56-G0003-001A1 (PDF) Use pkgcode/variation: PC1+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis
DS1643P-100			PWRCP;34 pin;607 mm² Dwg: 56-G0003-001A1 (PDF) Use pkgcode/variation: PC1-2*	0°C to +70°C	RoHS/Lead-Free: No Materials Analysis
DS1643P-100+			PWRCP;34 pin;607 mm² Dwg: 56-G0003-001A1 (PDF) Use pkgcode/variation: PC1+2*	0°C to +70°C	RoHS/Lead-Free: Lead Free Materials Analysis

More Information

Real-Time Clock Design Guide (PDF)

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