2The DS1388 I C real-time clock (RTC), supervisor, andEEPROM is a multifunction device that provides aclock/calendar, programmable watchdog timer, power-supply monitor with reset, and 512 bytes of EEPROM.The clock provides hundredths of seconds, seconds,minutes, and hours, and operates in 24-hour or 12-hourformat with an AM/PM indicator. The calendar providesday, date, month, and year information. The date at theend of the month is automatically adjusted for monthswith fewer than 31 days, including corrections for leapyear. A watchdog timer provides a reset for an unre-sponsive microprocessor. It is programmable in 10msintervals from 0.01 to 99.99 seconds. A temperature-compensated voltage reference and comparator circuit. If a primary power failure ismonitors the status of VCCdetected, the device automatically switches to thebackup supply and drives the reset output to the activestate. The backup supply maintains time and dateoperation in the absence of V . When V returns toCC CCnominal levels, the reset is held low for a period to allowthe power supply and processor to stabilize. Thedevice also has a pushbutton reset controller, whichdebounces a reset input signal. The device is2accessed through an I C serial interface.ApplicationsPortable InstrumentsPoint-of-Sale EquipmentNetwork Interface CardsWireless Equipment