NV RAM制御付リアルタイムクロック
DALLAS, TX—July 31, 2002—Dallas Semiconductor introduces the DS1558 watchdog clock with NV RAM control designed to complement the existing DS155x family of watchdog timekeeper modules. The DS1558 (when combined with an external crystal, battery, and SRAM) gives the same functionality as the DS155x modules, providing system designers with another choice in PCB layout and component selection while maintaining a common feature set.
The DS1558 is a full-function, real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and NV SRAM controller. User access to all registers within the DS1558 is accomplished with a bytewide interface. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary coded decimal (BCD) format. Corrections for day of month and leap year are made automatically.
The DS1558 also contains its own power-fail circuitry, which automatically protects the data in the clock and SRAM against out-of-tolerance VCCI conditions by inhibiting the CE-bar input when the VCC supply enters an out-of-tolerance condition. When VCCI goes below the level of VBAT, the external battery is switched on to supply energy to the clock and the external SRAM. This feature provides a high degree of data security during unpredictable system operation brought on by low VCC levels.
Available in a 48-pin TQFP, the DS1558 operates on either 5V or 3.3V power supplies and is available in the extended-industrial temperature range (-40°C to +85°C). Prices start at $3.92 (1000-up, FOB USA).
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