I²C RTC/Supervisor with Trickle Charger and 512 Bytes EEPROM

The DS1388 I²C real-time clock (RTC), supervisor, and EEPROM is a multifunction device that provides a clock/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-hour format with an AM/PM indicator. The calendar provides day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. A watchdog timer provides a reset for an unresponsive microprocessor. It is programmable in 10ms intervals from 0.01 to 99.99 seconds. A temperature-compensated voltage reference and comparator circuit monitors the status of VCC. If a primary power failure is detected, the device automatically switches to the backup supply and drives the reset output to the active state. The backup supply maintains time and date operation in the absence of VCC. When VCC returns to nominal levels, the reset is held low for a period to allow the power supply and processor to stabilize. The device also has a pushbutton reset controller, which debounces a reset input signal. The device is accessed through an I²C serial interface.

Applications

* Network-Interface Cards * Point-of-Sale Equipment * Portable Instrumentation * Wireless Equipment

* Fast (400kHz) I²C Interface

* RTC Counts Hundredths of Seconds, Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap Year Compensation Valid Up to 2100

* Programmable Watchdog Timer

* Automatic Power-Fail Detect and Switch Circuitry

* Reset Output with Pushbutton Reset Input Capability

* 512 x 8 Bits of EEPROM

* Integrated Trickle-Charge Capability for Backup Supply

* Three Operating Voltages: 5.0V, 3.3V, and 3.0V

* Low Timekeeping Voltage Down to 1.3V

* -40°C to +85°C Temperature Range