DS1388

· 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
· UL Recognized

Voltage Range on VCC Pin Relative to Ground .................-0.3V to +6.0V
Voltage Range on Inputs Relative to Ground ........-0.3V to (V_CC + 0.3V)
Operating Temperature Range (noncondensing) ...........-40°C to +85°C
Storage Temperature Range ........................................-55°C to +125°C
Soldering Temperature ...............See IPC/JEDEC J-STD-020 Specification

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The DS1388 I²C real-time clock (RTC), supervisor, and EEPROM is a multifunction device that provides a clock/calendar, programmable watchdog timer, powersupply monitor with reset, and 512 bytes of EEPROM. The clock DS1388 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 temperaturecompensated voltage reference and comparator circuit monitors the status of V_CC. 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 V_CC. When V_CC returns to nominal levels, the reset is held low for a period to allow the power supply and processor to stabilize. The device DS1388 also has a pushbutton reset controller, which debounces a reset input signal. The device is accessed through an I²C serial interface.