Power Electronics

Elapsed Time Counter Prevents Data Corruption

The DS1374 2-wire serial real-time clock (RTC) from Dallas Semiconductor combines a 32-bit binary counter, watchdog, period alarm, programmable square-wave output, and power-on reset.

The elapsed time counter's 32-bit binary counter increments once per second, and can be used to derive time of day, week, month, and year by using a software algorithm. It monitors Vcc, and when a power-fail occurs, it write-protects the internal registers, resets the processor, and switches to backup power to prevent data corruption. In low-power mode, the oscillator maintains timekeeping down to 1.3V, consuming less than 1 µ of current. When Vcc returns to nominal conditions, the DS1374 holds the processor in reset for 250 ms while operating conditions stabilize. An optional trickle-charging circuit backs up the DS1374 with a super cap or rechargeable battery. Additionally, the reset pin is monitored as a pushbutton input for externally generating a reset. Address and data are transferred serially through a 2-wire serial bus.

The DS1374 operates over the extended-industrial temperature range (-40° to 85°) and is available in a 10-pin microSOP package.

For more information, call 1-800-998-8800 or visit www.maxim-ic.com.

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