RX8130CE :I2C-Bus Interface Build in backup battery charge control function

  • Built in frequency adjusted 32.768 kHz crystal unit
  • Interface Type
    I2C-Bus interface
  • Interface voltage range
    1.6V to 5.5V
  • Wide voltage for time keeping
    1.1V to 5.5V
  • Low backup current
    300 nA ( Typ. )  / 3 V
  • Auto power switching function:Switchover by main power supply monitor.
  • Backup battery charge control function: For the rechargeable lithium batteries.
  • Reset functions with a delay:Detect a main power supply and remove the reset.
  • The various function include full calendar, alarm, timer, etc.
  • Epson prepared Linux driver for development
    The registered trademark Linux® is used pursuant to a sublicense from LMI(Linux Mark Institute)

Complies with EU RoHS directive.

Complies with EU RoHS directive.


Block diagram

Block diagram


  • I2C-Bus interface.
  • Auto power switching function
    • The VDD voltage is monitored and it switches to the backup power supply by the automatic operation. The switch voltage to the backup power supply. 1.25V (Min.)
    • Even if the main power supply voltage is decreased, the current flow from the backup power supply is prevented.
  • Charge control function for the rechargeable lithium batteries.
    • Stop charging automatically by detecting the full charge.
    • Records in the register detecting the backup power supply voltage decrease.
  • Reset function with a delay
    • When the main power is supplied, reset output is released.The release voltage is selected by the register. (2.80V / 2.75V)
    • Delay time from the voltage rise detection is 60ms Typ.
  • Frequency output function
    • Output frequency is selectable from 32.768kHz, 1024Hz,1Hz.
  • Timer function
    • Selectable in 1/4096 second from 65535 hours.
    • Timer source clock are 1hour, 1min, 64Hz, 4096Hz.
    • It is automatically recorded to TF-bit at the time of event occurrence, and possible to output with /IRQ pin.

Specifications (characteristics)

Refer to application manual for details.

Recommended Operating Conditions

Item Symbol Conditions Min. Typ. Max. Unit
Operating supply voltage VDD - 1.25 3.0 5.5 V
Clock supply voltage VCLK - 1.1 3.0 5.5 V
Operating temperature TOPR - -40 +25 +85 °C
VDD detect voltage -VDET2 VDD,Fall 1.20 1.30 1.40 V

Frequency characteristics

Item Symbol Conditions Rating Unit
Frequency tolerance Δ f / f Ta = +25 °C
VDD = 3.0 V
B : 5 ± 23* x 10-6
Oscillation start-up time tSTA VDD =2.75V to 5.5V 1 Max. s

*Equivalent to ±1 minute of monthly deviation (excluding offset.)

Current consumption characteristics

Item Symbol Conditions Min. Typ. Max. Unit
Current consumption IBK SCL=SDA = "L" ,
- 300 500 nA
V32K SCL=SDA = "H" ,
FOUT=32.768kHz, /IRQ=OFF,
FOUT pin CL=15pF
- 3.5 4.0 µA


Pin function

Signal Name I / O Function
SCL input Serial clock input pin.
SDA Input / Output Data input and output pin.
FOUT Output Frequency output pin with output control function. (C-MOS)Output frequency can be selected
as 32.768kHz, 1024Hz, 1Hz.
/ RST Output Reset output pin.(N-ch open drain)
In case of VDD voltage drop detection, a reset signal is outputted.
In case of VDD voltage rise detection, it is released reset signal after 60ms.
/ IRQ Output Interrupts output by Alarm and Timer events.(N-ch open drain)
VDD - This is a power-supply pin. It can impress the voltage unlike VIO.
VIO - This is a interface power supply pin. This is a pin to supply the voltage same as a host.
Vout - Internal voltage output pin. Connect smoothing capacitor of 1.0µF
VBAT - This is a power supply pin for backup battery.
This is a pin to connect a large-capacity capacitor, a secondary battery,a primary battery.
In a backup power supply operating range, the voltage is supplied inside by this pin.
GND - Connected to a ground

Terminal connection/External dimensions

Terminal connection External dimensions

(Unit: mm)

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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