STMicroelectronics Introduces Real-Time Clock Chips To Widen Designers' Price and Performance Choices.Business Editors/High-Tech Writers GENEVA--(BUSINESS WIRE)--Oct. 8, 2001 Two RTC See real time clock. Devices Feature Programmable Alarm and Interrupt, Watchdog Timer and Write-protect Function for Added Reliability STMicroelectronics (NYSE NYSE See: New York Stock Exchange :STM (Scanning Tunneling Microscope) A microscope that can image down to the atomic level. An STM uses a piezoelectric tube with a tiny sharp tip at the end that is moved within nanometers of the object being sampled. ) announces two serial real-time clock (RTC) chips, expanding the company's M41Txx family of microprocessor supervisor ICs. Of the two introductions, the feature-rich M41T94 touts an RTC accessible via a Serial Peripheral Interface (communications, hardware) Serial Peripheral Interface - (SPI) A serial interface in which a master device supplies clock pulses to exchanges data serially with a slave over two data wires (Master-Slave and Slave-Master). (SPI (1) (Stateful Packet Inspection) See stateful inspection. (2) (Service Provider Interface) The programming interface for developing Windows drivers under WOSA. ), power-on-reset/low-voltage detector, low-battery monitor, programmable alarm and interrupt function, watchdog timer, push-button (electronics) push-button - A roughly fingertip-sized plastic cover attached to a spring-loaded, normally-open switch, which, when pressed, closes the switch. Typical examples are the keys on a computer or calculator keyboard and mouse buttons. microprocessor reset, and non-volatile RAM. The second of the two introductions, the M41T81, stresses small size and high value, and includes an RTC, programmable alarm and interrupt function, and watchdog timer. As part of their protective functions, both the M41T94 and M41T81 switch automatically to an optional external lithium battery should power fail, providing a write-protect function in the process for added reliability. Typical targets for both RTCs include DVD players, metering and medical equipment, point-of-sale terminals, and virtually any device that contains a microcontroller or microprocessor. First and foremost among the chips' features is an RTC that makes available to the user, in binary-coded decimal (BCD) format, the present time from the century to tenths and hundredths of a second. The clock operates from a 2.0V (2.7V for the M41T94) to 5.0V supply and uses a built-in 32.768kHz 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 and external crystal. In addition, the M41T94's power-on-reset/low-voltage detector and low-battery flag can be set to trigger microprocessor reset signals at one of two voltage points. Specifically, with the chip's voltage threshold input tied to the supply voltage, VCC, the chip's power-fail deselect deselect Verb 1. computing to cancel (a highlighted selection of data) on a computer screen 2. Brit politics (of a constituency organization) to refuse to select (an MP) for re-election function activates if the voltage drops to 4.40V+/-0.10V. Alternatively, the power-fail deselect function can be set to activate at 2.65+/-0.05V by connecting the chip's threshold input to ground, VSS. Of the functions that both chips have in common, like the programmable alarm, watchdog, and square-wave functions, the alarm has repeat and battery back-up modes, the watchdog interval can be set from 62.5ms to 128s, and the square-wave frequency is adjustable from 1Hz to 32kHz. Communication with M41T94 is done over its synchronous SPI bus. For the M41T81, communication is over a 400-KHz Inter-IC (I2C) bus. Another feature of the M41T94 is its two power-on reset inputs, which issue a reset pulse output if either is active. Of the two inputs, one is de-bounced for pushbutton push·but·ton n. also push button A small button that activates an electric circuit when pushed. adj. also push-but·ton Equipped with or operated by a pushbutton. operation. In all, the M41T94 offers five sources for generating a reset: the two reset inputs, during power-on and low-voltage conditions, and from its watchdog timer. The M41T94 also has 64 bytes of memory space comprised of 20 bytes for the RTC registers and 44 bytes for general-purpose use. To meet power budgets and extend battery life, both the M41T94 and M41T81 use power sparingly. Specifically, the M41T94 operates from 2.7 to 5.5V and draws 2.0mA from the supply, which falls to 500nA under battery power. The M41T81 operates from 2.0 to 5.5V and draws just 400uA of supply current. Moreover, that current flow drops to a mere 1uA under battery operation. The M41T94 comes in a 16-pin SOIC (Small Outline IC) A small-dimension, plastic, rectangular, surface mount chip package that uses gull-wing pins extending outward. See gull-wing lead, SOJ and chip package. . It also is available in the 28-pin SNAPHAT(R) SOIC package for use with STMicroelectronics' SNAPHAT(R) Battery and Crystal top. The M41T81 comes in an SO-8 package. Both chips are specified over the industrial temperature range of -40 degrees to +85 degrees C. Additional information for these and other STMicroelectronics RTC devices is available at www.st.com/nvram. About STMicroelectronics STMicroelectronics is the world's third largest independent semiconductor company. The Company shares are traded on the New York Stock Exchange New York Stock Exchange (NYSE) World's largest marketplace for securities. The exchange began as an informal meeting of 24 men in 1792 on what is now Wall Street in New York City. , on Euronext Paris and on the Milan Stock Exchange Milan Stock Exchange The largest regional stock exchange in Italy, facilitating more than 90% of the country's trading volume. . The Company designs, develops, manufactures and markets a broad range of semiconductor integrated circuits (ICs) and discrete devices used in a wide variety of microelectronic applications, including telecommunications systems, computer systems, consumer products, automotive products and industrial automation and control systems. In 2000, the Company's net revenues were $7,813.2 million and net earnings were $1,452.1 million. Further information on ST can be found at www.st.com Note to Editors: In the 5th paragraph, in the terms "VCC" and "VSS" the letters CC and SS should be subscripted. |
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