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The X1243 is a Real Time Clock with clock/calendar circuits and two alarms. The dual port clock and alarm registers allow the clock to operate, without loss of accuracy, even during read and write operations.

The clock/calendar provides functionality that is controllable and readable through a set of registers. The clock, using a low cost 32.768kHz crystal input, accurately tracks the time in seconds, minutes, hours, date, day, month and years. It has leap year correction and automatic adjustment for months with less than 31 days.

An alarm match of the RTC sets an interrupt flag and activates an interrupt pin. An alternative alarm function provides a pulsed interrupt for long time constant timebases.

The device offers a backup power input pin. This V_BACK pin allows the device to be backed up by a nonrechargeable battery. The RTC is fully operational from 1.8 to 5.5 volts.

The X1243 provides a 2Kbyte EEPROM array, giving a safe, secure memory for critical user and configuration data. This memory is unaffected by complete failure of the main and backup supplies.

Key Features

• 2 alarms - interrupt output
  • Settable on the second, 10s of seconds, minute, 10s of minutes, hour, day, month, or day of the week
  • Repeat alarm for time base generation
• 2-wire interface interoperable with I2C
  • 400kHz data transfer rate
• Secondary power supply input with internal switch-over circuitry
• 2Kbytes of EEPROM
  • 64-byte page write mode
  • 3-bit Block Lock™ protection
• Low power CMOS
  • <1µA operating current
  • <3mA active current during program
  • <400µA active current during data read
• Single byte write capability
• Typical nonvolatile write cycle time: 5ms
• High reliability
• Small package options
  • 8-lead SOIC package, 8-lead TSSOP package