REPEAT/Temperature-Compensated Crystal Oscillator from Dallas Semiconductor is Industry's Most Accurate.DALLAS--(BUSINESS WIRE)--Oct. 12, 1998-- New DS32KHz Meets 1998 European Server Recommendation; Provides Accuracy as Great as +/-1 Minute per Year Dallas Semiconductor Dallas Semiconductor, now a subsidiary of Maxim Integrated Products, designs and manufactures analog, digital, and mixed-signal semiconductors (integrated circuits, or ICs). Monday announced an oscillator oscillator Mechanical or electronic device that produces a back-and-forth periodic motion. A pendulum is a simple mechanical oscillator that swings with a constant amplitude, requiring the addition of energy at each swing only to compensate for the energy lost because of air that meets the precision timekeeping requirements of large computer networks, financial transaction processing Updating the appropriate database records as soon as a transaction (order, payment, etc.) is entered into the computer. It may also imply that confirmations are sent at the same time. Transaction processing systems are the backbone of an organization because they update constantly. applications, and timed-access communications. A temperature-compensated crystal oscillator (TCXO TCXO Temperature Compensated Crystal Oscillator TCXO Temperature-Controlled Crystal Oscillator ), the DS32KHz meets the 1998 European network server recommendation for real-time clock (RTC See real time clock. ) accuracy. The new device provides accuracy as great as +/-1 minute per year (+/-2 parts per million parts per million mg/kg or ml/l; see ppm. ) in operation from 0 to 40 degrees Celsius, making it the industry's most accurate 32.768-kHz oscillator. Economical quartz crystals provide the time references in real-time clock circuits for computers and many other electronic systems. Unfortunately, the electromechanical The use of electricity to run moving parts. Disk drives, printers and motors are examples. Electromechanical systems must be designed for the eventual deterioration of moving components that wear over time. The first TVs were electromechanical systems (see video/TV history). sensitivities of these crystals can cause instabilities in their output frequencies. As a result, uncompensated uncompensated (  n·kômˑ·p crystals can cause system clocks to gain or lose as much as 100 minutes per year in operation over the industrial temperature range. The accepted standard of accuracy in modern electronic systems is +/-1 minute per month at 25 degrees Celsius and +/-40 minutes per year at 60 degrees Celsius. The steady 32.768 kHz output of the DS32KHz can maintain the accuracy of real-time clocks within +/-4 minutes per year (+/-7.5 ppm) over the industrial temperature range (-40 to 85 degrees Celsius) and within +/-1 minute per year from 0 to 40 degrees Celsius. Device Sets a New Standard of Accuracy "Accurate timekeeping is very important in network servers that have lots of PCs connected to them," said Doug Cole, product manager. "With timed-access communications, there's a need for accuracy and synchronization." The same need exists for financial transactions processed at point-of-sale terminals. When a great deal of information is coming in and every system time-stamps it differently, more accurate references are needed. "Nobody puts an RTC in a system and expects it to keep inaccurate time," Cole said. "People don't understand why a $9.95 watch can keep accurate time but a $3,000 PC and a $20,000 server can't. Watches keep good time because they're trimmed to operate at body temperature." Real time clocks are calibrated cal·i·brate tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates 1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): to keep time accurately at 25 degrees Celsius. If temperatures are hotter or colder, the clocks run more slowly. Accuracy over temperature typically depends on crystal characteristics, and higher accuracy over temperature is achievable by trimming the crystal. Accuracy needs to be repeatable day in and day out Adv. 1. day in and day out - without respite; "he plays chess day in and day out" all the time , Cole said. Timekeeping in remote applications that operate at elevated temperatures can be significantly inaccurate. The effect of temperature on accuracy is cumulative; it is not self-correcting. Accurate, Economical Replacement The DS32KHz is an accurate, economical replacement for standard 32.768-kHz crystals and oscillators. The TXCO's output can be used to drive the X1 input of most RTC chips, chipsets and other ICs that contain RTCs. Inside the compact, surface mount package are a quartz crystal and a temperature-compensation IC. The compensation IC employs low current oscillator technology and Dallas' proprietary thermal-sensing technology. No external trimming capacitors are required, and no calibration is needed after the device leaves the factory. Patent protection for the compensation chip is pending. Dallas supplies the device in an industry-standard Ball-Grid Array (BGA (Ball Grid Array) A popular surface mount chip package that uses a grid of solder balls as its connectors. Available in plastic and ceramic varieties, BGA is noted for its compact size, high lead count and low inductance, which allows lower voltages to be used. ) package that is compatible with pick-and-place technology and conventional convection reflow (1) The process of heating and melting the solder that has been screen printed onto a printed circuit board in order to bond chips and other components to the board. Surface mount chips (SMT) use the reflow method. Contrast with wave soldering. See also reflowable text. assembly methods. The package measures 0.40 wide, 0.45 long, and 0.18 inches high; it has 36 pins, but only four pin connections are required for operation. Recommended Land Pattern Layout Dallas provides a land pattern layout for the package that is compatible with standard 32.768 kHz crystals or the DS32KHz. No hardware modifications are required. The recommended layout, available on the Dallas Semiconductor Web site, can be used in both new designs and board revisions. A single backup battery powers the DS32KHz and the RTC, providing continuous timekeeping if system power fails. The TCXO integrates the required battery switch circuitry. Available in commercial and industrial temperature versions, the DS32KHz operates from supplies ranging from 2.7 to 5.5 volts, and current consumption in battery-backed mode is 1 micro Amph typical. Currently available from stock, the commercial version of the DS32KHz costs $5.28 in quantities of 1,000. Dallas Semiconductor is the world's largest supplier of stand-alone integrated circuit RTCs. |
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