2-wire Realtime Clock S-35399A03

The S-35399A03 is a CMOS 2-wire real-time clock IC which operates with the very low current consumption and in the wide range of operation voltage. The operation voltage is 1.3 V to 5.5 V so that this IC can be used for various power supplies from main supply to backup battery. Due to the 0.34 µA current consumption and wide range of power supply voltage at time keeping, this IC makes the battery life longer. In the system which operates with a backup battery, the included free registers can be used as the function for user’s backup memory. Users always can take back the information in the registers which is stored before power-off the main power supply, after the voltage is restored. This IC has the function to correct advance/delay of the clock data speed, in the wide range, which is caused by the oscillation circuit’s frequency deviation. Correcting according to the temperature change by combining this function and a temperature sensor, it is possible to make a high precise clock function which is not affected by the ambient temperature. Moreover, this IC has a 24-bit binary up counter. This counter counts up every 60 sec from power-on so that users are able to grasp the elapsed time from power-on up to 30 years.


Low current consumption
0.34 µA typ. (VDD = 3.0 V, Ta = 25°C)
Wide range of operating voltage
1.3 to 5.5 V
Built-in clock-correction function
Built-in 24-bit binary up counter
Built-in free user register
2-wire (I2C-bus) CPU interface
Built-in alarm interrupter
Built-in flag generator during detection of low power voltage or at power-on
Auto calendar up to the year 2099, automatic leap year calculation function
Built-in constant voltage circuit
Built-in 32.768 kHz crystal oscillator (Cd built in, Cg external)
Lead-free product


  • Mobile game devices
  • Mobile AV devices
  • Digital still cameras
  • Digital video cameras
  • Electronic power meters
  • DVD recorders
  • TVs, VCRs
  • Mobile phones, PHS
  • Car navigation