Timer ICs / ASSPs

2-wire Realtime Clock S-35391A

The S-35391A is a CMOS 2-wire real-time clock IC which operates with the very low current consumption in the wide range of operation voltage. The operation voltage is 1.3 V to 5.5 V so that the S-35391A can be used for various power supplies from main supply to backup battery. Due to the 0.25 µA current consumption and wide range of power supply voltage at time keeping, the S-35391A 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. The S-35391A has the function to correct advance / delay of the clock data speed, in the wide range, which is caused by the crystal 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.
S-35391A, designed to bus arbitration that separates IDs for identifying devices (device codes) so that system processing works without collision, is a product having different device code from S-35390A.


Low current consumption
0.25 µA typ. (VDD = 3.0 V, Ta = +25°C)
Wide range of operating voltage
1.3 V to 5.5 V
Built-in clock correction function
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 oscillation circuit (built-in Cd, external Cg)
Lead-free, Sn 100%, halogen-free


  • Mobile game device
  • Mobile AV device
  • Digital still camera
  • Digital video camera
  • Electronic power meter
  • DVD recorder
  • TV, VCR
  • Mobile phone, PHS

Standard Circuit

Standard Circuit

Parts List

  • U(Ux), S and G at the end of the product name of ABLIC Inc. were used to indicate different material specifications as “environmental code”,
    however, these have now been unified into “lead-free and halogen-free” and are identical in terms of environmental quality.
  • Note: Lead-free plating other than 100% Sn is applied to some limited old products, therefore, please contact our sales representatives for details.
  • These descriptions may be different from the actual product name and parameter.
    Please confirm the product name and specifications with the data sheet again.
  • The information herein is subject to change without notice.