DS1340

·Enhanced Second Source for the ST M41T00
·Available in a Surface-Mount Package with an Integrated Crystal (DS1340C)
·Fast (400kHz) I²C Interface
·Software Clock Calibration
·RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year
·Automatic Power-Fail Detect and Switch Circuitry
·Trickle-Charge Capability
·Low Timekeeping Voltage Down to 1.3V
·Three Operating Voltage Ranges (1.8V, 3V, and 3.3V)
·Oscillator Stop Flag
·Available in 8-Pin |ìSOP or SO Package
·Underwriters Laboratory (UL) Recognized

Portable Instruments
Point-of-Sale Equipment
Medical Equipment
Telecommunications

The DS1340 is a real-time clock (RTC)/calendar that is pin compatible and functionally equivalent to the ST M41T00, including the software clock calibration. The device DS1340 additionally provides trickle-charge capability on the V_BACKUP pin, a lower timekeeping voltage, and an oscillator STOP flag. Block access of the register map is identical to the ST device. Two additional regis- ters, which are accessed individually, are required for the trickle charger and flag. The clock/calendar pro- vides seconds, minutes, hours, day, date, month, and year information. A built-in power-sense circuit detects power failures and automatically switches to the back- up supply. The device is programmed serially through I²C^TM bidirectional bus.