New Real-Time Clock Provides Unprecedented +/-2 Minutes Per Year Accur

    Business Editors/High-Tech Editors

    DALLAS, Texas--(BUSINESS WIRE)--April 7, 2005--Dallas Semiconductor (Nasdaq:MXIM):


    -- Note to Editor: A new real-time clock (RTC), the DS3231,
    integrates a TCXO, RTC, and 32.768KHz crystal into a low-cost,
    standard 16-pin SOIC. Timekeeping accuracy is +/-2 minutes per
    year over the -40 degrees Celsius to +85 degrees Celsius
    temperature range. This unprecedented performance makes the
    DS3231 today's optimal solution for applications where
    timekeeping accuracy is critical. Additional integrated
    capabilities expand the system applications and options for
    this RTC.

    Dallas Semiconductor (Nasdaq:MXIM) today announced the DS3231, a real-time clock (RTC) that provides better than +/-2 minutes per year accuracy over an extremely wide operating-temperature range: -40 degrees Celsius to +85 degrees Celsius. With ease of use for the designer, low-cost packaging, and the part's many integrated functions, the DS3231 is unquestionably the most cost effective, integrated solution for applications requiring extremely accurate timekeeping. These applications include servers, electricity meters, security and access control systems, fleet management, telematic systems, GPS and navigation equipment, POS terminals, and ATMs.

    The Historical Problems with Clock Accuracy

    Typically before the DS3231, economical quartz crystals provided the time reference in RTC circuits for many electronic systems. Unfortunately, the electromechanical and thermal sensitivities of those crystals introduced instabilities in their output frequencies. As a result, uncompensated crystals caused system clocks to gain or lose as much as 100 minutes per year in operation over the -40 degrees Celsius to +85 degrees Celsius industrial temperature range. That margin of error is no longer acceptable. Today's critical applications such as time-stamping of important events, financial transactions, time-based rate or billing changes, or event initiation (i.e., TDMA systems that require communication at specific times) typically require accuracies better than +/-10 minutes/year (or restated, +/-4ppm).
    The traditional crystal used to make 32.768KHz frequencies is of the tuning-fork type and has a parabolic frequency drift with respect to temperature. The drift over temperature can be greater than 100ppm. This results in hundreds of minutes of timekeeping error, which would require periodic correction for accurate long-term operation. "Compensating quartz crystals to provide accuracies of less than +/-2 minutes per year is no easy task," said Paul Nunn, Business Manager of TCXO products at Maxim/Dallas Semiconductor. "A significant investment of time, money, and infrastructure development is required to individually correct each crystal's natural temperature characteristics at the volumes required by the marketplace," Nunn added.

    How Systems Needing RTC Accuracy Addressed this Well-Recognized Problem

    Manufacturers and system users traditionally relied on three options to compensate for the temperature drift: in-line calibration during the manufacturing process, microprocessor-scheduled updates using crystal correction codes based on ambient temperature, or in-field servicing to correct timekeeping. Other systems even relied on the Global Positioning Satellite (GPS) system to receive and correct time. GPS is an extremely accurate source for time. But for reliable measurement, systems users must ensure that their system is in line-of-sight of the GPS satellite system. That may not always be possible, much less convenient.
    All these methods for attaining RTC accuracy better than the traditional +/-100 minutes per year are either cumbersome or expensive. "Each of these methods can be costly. The resulting accuracy, moreover, is typically no better than +/-20ppm (+/-10 minutes per year) over a narrower, 0 to +40 degrees Celsius temperature range," Nunn explained.

    Pushing Accuracy Down to +/-2 Minutes per Year

    The DS3231 RTC combines a highly stable TCXO, RTC, and a 32.768KHz crystal into a single package. Timekeeping accuracy is maintained within +/-2 minutes per year. The device requires no calibration by the end-user before, during, or after the final assembly of the device. It eliminates crystal sourcing. When compared to alternative crystal-based solutions, the DS3231 provides up to five times better accuracy/performance over the entire -40 degrees Celsius to +85 degrees Celsius temperature range.

    Additional DS3231 Capabilities

    The DS3231 provides more than just timekeeping accuracy. Additional capabilities expand the host of system solutions and options. The device integrates an extremely accurate digital temperature sensor which (like the time) is accessed through the I(2)C* port. The temperature sensor provides +/-3 degrees Celsius accuracy. Automatic power detection and power switching between a main power source and a secondary energy source (i.e., low-voltage batteries) is managed by on-chip controls. In the event of main power loss, the device continues to provide accurate time and temperature without degradation. An on-board interrupt can be used to restart the system microprocessor when main power is reapplied or back in-tolerance.

    Applying +/-2 Minutes/Year Accuracy to Real-World Challenges

    Accurate timekeeping down to +/-2 minutes per year makes the DS3231 RTC the only IC to solve many of the time-base issues remaining for end-equipment from electricity meters to navigation systems.
    Today's electricity meters are built to varying specifications and requirements. One category of power meters is required to log multirate energy usage, to track the energy consumed and the time of day so the power companies can bill accordingly. It is critical that multirate meters record this switching from one rate to another very accurately. The DS3231 is the only integrated solution that can meet those stringent accuracy requirements today.
    In access-control, security-based systems or time-and-attendance systems where timed-based admittance is used, regular day-to-day operations can be seriously impeded if access to business property is denied or the monitoring of job-related activities is flawed because of an inaccurate or changing time source. By implementing more accurate timekeeping solutions, as precise as +/-2 minutes per year with the DS3231 RTC, these access systems will immediately benefit in many ways, like more efficient property utilization, more accurate payroll records, better managed employee work schedules, more reliable security and access data.
    The DS3231 RTC is available in commercial and industrial temperature versions, operates from 2.3V to 5.5V power supplies, and is provided in a low-cost standard 16-pin, 300 mil SOIC for ease of handling and manufacturing. The data sheet and samples are available at www.maxim-ic.com. Production volumes are available March 2005.

DS3231 RTC Major Specifications

Device Name Extremely Accurate Real-Time Clock--TCXO--Crystal ---------------------------------------------------------------------- Package Size 16-Pin, 300 mil SOIC ---------------------------------------------------------------------- Operating Voltage (V) 2.3 to 5.5 ---------------------------------------------------------------------- Timekeeping Accuracy +/- 3ppm (-40 degrees Celsius to (over temp) +85 degrees Celsius) +/- 1ppm (0 to +40 degrees Celsius) ---------------------------------------------------------------------- Current Consumption (microamp) 1.5 (typ); 4.0 (max) ----------------------------------------------------------------------

    Dallas Semiconductor is a wholly owned subsidiary of Maxim Integrated Products, a leading international supplier of quality analog and mixed-signal products for applications that require real world signal processing. For more information, contact Maxim at 120 San Gabriel Dr., Sunnyvale, CA 94086. Telephone: 408-737-7600 or our URL: www.maxim-ic.com.

    GRAPHIC: The graphic for this product is also available on the web in three formats:

    PREVIEW image (smaller image to view in Navigator or Explorer):

    http://www.maxim-ic.com/PRGraphics/images/DSPR3231.jpg

    JPEG (300 dpi, high quality, RGB color)

    http://www.maxim-ic.com/PRGraphics/images/DS3231.jpg

    TIFF (300 dpi uncompressed CMYK TIFF, in a .ZIP archive*)

    http://www.maxim-ic.com/PRGraphics/images/DS3231-cmyk-tif.zip

    *Purchase of I(2)C components from Maxim Integrated Products, Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I(2)C Patent Rights to use these components in an I(2)C system, provided that the system conforms to the I(2)C Standard Specification as defined by Philips.

--30--AD/sf*

CONTACT: Dallas Semiconductor Paul Nunn, 972-371-4089 (Editors) Customer Service, 1-800-998-8800 (Readers)

KEYWORD: CALIFORNIA TEXAS INDUSTRY KEYWORD: HARDWARE AUTOMOTIVE AEROSPACE/DEFENSE GOVERNMENT MANUFACTURING PRODUCT SOURCE: Dallas Semiconductor

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