RA-8581SA (For Automotive I2C-Bus Interface Real Time Clock Module)

  • Built-in frequency adjusted 32.768kHz crystal unit.
  • Interface Type
    I2C-Bus Interface(400kHz)
  • Operating voltage range
    1.8V to 5.5V
  • Wide Timekeeper voltage range
    1.6V to 5.5V
  • Low backup current
    0.45µA / 3V(Typ.)
  • 32.768 kHz frequency output function
    C-MOS output With Control Pin
  • The various functions include full calendar, alarm, timer.
  • Conforms to AEC-Q200
  • *The I2C-Bus is a trademark of NXP Semiconductors


Complies with EU RoHS directive.


Block diagram

Block diagram


  • Interface Type
    • I2C-Bus interface. (Hi-speed bus specifications 400kHz)
    • * I2C-Bus slave address : read A3h and write A2h
  • 32.768kHz frequency output function
    • FOUT pin output (C-MOS output ), CL=30 pF
    • 32.768kHz clock frequency output. (Duty 50 ±5%)
  • Timer function
    • Timer interrupt function can be set up between 1/4096second and 4095minutes.
    • It is recorded automatic to TF-bit at the time of event
      occurrence,and possible to output with /TIRQ pin output
      (N-ch open-drain output).
  • Interrupt function
    • Alarm interrupt function, Time update interrupt function.

Specifications *Refer to application manual for details.

Recommend Operating Conditions

Item Symbol Condition Min. Typ. Max. Unit
Power voltage VDD - 1.8 3.0 5.5 V
Clock voltage VCLK - 1.6 3.0 5.5 V
Operating temperature TOPR - -40 +25 +85 °C

Frequency characteristics

Item Symbol Condition Rating Unit
Frequency tolerance Δ f/f Ta=+25°C
5±23 * ×10-6
FOUT output Duty tw/t Ta=-40°C to +85°C
VDD=2.4V to 5.5V
50±5 %

*1 Equivalent to ±1 minutes of monthly deviation.

Current consumption characteristics

Ta=-40°C to +85°C

Item Symbol Conditions Min. Typ. Max. Unit
Current Consumption lBK fSCL=0Hz

VDD=5V 0.65 1.2 µA
VDD=3V 0.45 0.8
l32k fSCL=0Hz

FOUT;32.768kHz Output ON
VDD=5V 8.0 20.0 µA
VDD=3V 5.0 12.0


Pin function

Signal Name Input/Output Function
SCL Input Serial clock input pin
SDA Bi-directional Data input and output pin
FOUT Output FOUT pin outputs the reference clock signal at 32.768 kHz.
FOE pin inputs the FOUT output control.
FOE pin
FOUT pin
HIGH Output (C-MOS)
FOE Input
/INT Output Interrupt output (N-ch open drain)
VDD - Connected to a positive power supply.
GND - Connected to a ground.

Terminal connection / External dimensions

Terminal connection External dimensions

(Unit: mm)

The metal case inside of the molding compound may be exposed on the top or bottom of this product.
This purely cosmetic and does not have any effect on quality, reliability or electrical specs.

Footprint (Recommended)


(Unit: mm)

To maintain stable operation, provide a 0.1uF by-pass capacitor
at a location as near as possible to the power source terminal of the crystal product (between Vcc - GND).

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