概述
　　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 additionally provides trickle-charge capability on the VBACKUP pin, a lower timekeeping voltage, and an oscillator STOP flag. Block access of the register map is identical to the ST device. Two additional registers, which are accessed individually, are required for the trickle charger and flag. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. A built-in power-sense circuit detects power failures and automatically switches to the backup supply. The device is programmed serially through an I²C bidirectional bus.
　　关键特性
　　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 µSOP or SO Packages
　　应用
　　医疗装置
　　销售终端机(POS)装置
　　便携式仪表
　　电信
　　DS1340、DS1340C典型工作电路

　　关键参数