RA8900CE :I2C-Bus Interface Real Time Clock Module For Automotive
(Built-in 32.768 kHz-DTCXO, High Stability and Power Switching)


Complies with EU RoHS directive. PB Free Automotive
  • Built in frequency adjusted 32.768 kHz crystal unit and DTCXO.
  • Interface Type
    I2C-Bus interface (400kHz)
  • Interface voltage range
    2.5V to 5.5V
  • Temp. compensated voltage range
    2.0V to 5.5V
  • Timekeeping voltage range
    1.6V to 5.5V
  • Selectable clock output(32.768 kHz, 1024 Hz, 1 Hz)
  • The various functions full calendar, alarm, timer, temp. sensor
  • Applications : Car audio, Car navigation system, Clock
  • Conforms to AEC-Q200
  • * The I2C-BUS is a trademark of NXP Semiconductors.

Block diagram

Block diagram


  • High Stability
    • UA ± 3.4 x 10-6 / -40 °C to +85 °C ( Equivalent to 9 seconds of month deviation )
    • UB ± 5.0 x 10-6 / -40 °C to +85 °C ( Equivalent to 13 seconds of month deviation )
    • UC ± 5.0 x 10-6 / -30 °C to +70 °C ( Equivalent to 13 seconds of month deviation )
  • 32.768 kHz frequency output function
    • FOUT pin output (C-MOS output), CL=30 pF
    • Output selectable: 32.768 kHz, 1024 Hz, 1 Hz
  • Available automatic battery backup switch-over function
    • Charge from VDD to backup battery connected to VBAT is possible.
      VDD voltage drop(VDET3) detection and automatically switches to the backup battery.
      This circuit is optimal to backup with a secondary battery and a large capacitor.
  • Timer function
    • Timer function can be set up between 1/4096 second and 4095 minutes.
  • Alarm function
    • Alarm function can be set to day of week, day, hour, and minute.
  • Temp. sensor function
    • The temperature data are output to a register by a temp. sensor function. (Bank.2_Add17h)

Pin function

Signal Name I / O Function
T1(CE) input Use by the manufacture for testing.
( Do not connect externally.)
SCL input Serial clock input pin.
FOUT output The pin outputs the reference clock signal.
( CMOS output )
VBAT - Battery supply.
This pin has charge capability to backup battery.
VDD - Connected to a positive power supply
FOE input The input pin for the FOUT output control.
/ INT output Interrupt output (N-ch. open drain).
GND - Connected to a ground
T2(VPP) - Use by the manufacture for testing.
( Do not connect externally.)
SDA I/O Data input and output pin.

Terminal connection/External dimensions

Terminal connection External dimensions

(Unit: mm)

Specifications (characteristics)

Refer to application manual for details.

Electrical Characteristics

Item Symbol Conditions Min. Typ. Max. Unit
Operating voltage VDD Interface voltage 2.5 3.0 5.5 V
Temp. compensated Voltage VTEM Temp. compensated voltage 2.0 3.0 5.5 V
Clock supply voltage VCLK Internal clock 1.6 3.0 5.5 V
Operating temperature TOPR No condensation -40 +25 +85 °C
Stability Δ f/f UA Ta=-40°C to+85°C
±3.4 *1 x10-6
UB Ta=-40°C to+85°C
±5.0 *2
UC Ta=-30°C to+70°C
Current consumption(1) lDD1 fSCL=0Hz,/INT=VDD,
VDD=VBAT FOUT:OFF Temp. Compensation
interval 2.0 s.
VDD=5V - 0.72 1.5 µA
Current consumption(2) lDD2 VDD=3V - 0.70 1.4

*1 Equivalent to 9 seconds of month deviation.
*2 Equivalent to 13 seconds of month deviation.

32.768 kHz-DTCXO Frequency temperature characteristics (Example)

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