MAXIM DS1340Z-3+

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. Reads and writes are inhibited while the clock continues to run. The device is programmed serially through an I2C bidirectional bus.

• Enhanced Second Source for the ST M41T00
• Completely Manages All Timekeeping Functions
• RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year
• Software Clock Calibration
• Oscillator Stop Flag
• Low-Power Operation Extends Battery Backup Run Time
• Low Timekeeping Voltage Down to 1.3V
• Automatic Power-Fail Detect and Switch Circuitry
• Trickle-Charge Capability
• Three Operating Voltage Ranges (1.8V, 3V, and 3.3V) Supports Systems Using Legacy and Modern Power Buses
• Surface-Mount Package with an Integrated Crystal (DS1340C) Saves Additional Space and Simplifies Design
• Simple Serial Port Interfaces with Most Microcontrollers
• Fast (400kHz) I2C Interface
• 8-Pin SOP or SO Package Minimizes Required Space
• Underwriters Laboratories (UL) Recognized

• Portable Instruments
• Point-of-Sale Equipment
• Medical Equipment
• Telecommunications