RX-8035LC (I2C-Bus Real Time Clock Module)

  • Built in 32.768 kHz crystal unit
    Frequency adjusted for high accuracy.
  • Interface Type
    I2C-Bus Interface(400kHz)
  • Operating voltage range
    2.4V to 5.5V
  • Wide voltage for Timekeeping
    1.0V to 5.5V
  • Low backup current
    350nA(SA) 400nA(LC)/ 3V(Typ.)
  • Event detection and Time stamp
    One-shot full timestamp and interrupt.
  • Dual event detection ports
    Each terminal has a de-bounce circuit.
  • Auto power switching functions
    It switches VDD and VBAT, automatically
  • Dual Alarm, Periodic interruption
  • Epson prepared Linux driver for development
  • https://www5.epsondevice.com/en/information/support/linux_rtc/
    The registered trademark Linux® is used pursuant to a sublicense from LMI(Linux Mark Institute)

Complies with EU RoHS directive.


Block diagram

Block diagram


  • The event detection and Timestamp function
    • Dual event detection terminals.
    • Selectable de-bounce period 35ms or 2s.
    • Available event detection interrupt output.
  • Power switching functions.
    • An external diode is unnecessary to have a reverse current prevention switch built-in in
      the VBAT side to connect a primary cell to.
    • When VDD is less than 2.4V, an internal source is switched to VBAT, and /RES is Low level.
      When VDD voltage rises to higher than 2.52V, an internal source is switched to VDD, and /RES is released with 105ms delay.
    • Note: When the supply from VBAT, SCL and SDA are disabled.
  • Alarm, Periodic interrupt, 32.768kHz clock output.
    • Available monthly-alarm and weekly-alarm.
    • Interrupt period are selectable from 2Hz to Monthly.
    • CLKOUT outputs 32.768kHz clock powered by VDD.

Specifications (characteristics) *Refer to application manual for details.

Recommend Operating Conditions

Item Symbol Conditions Min. Typ. Max. Unit
Operating voltage VACCESS VDD 2.4 3.0 5.5 V
Time keeping voltage VCLK VBAT 1.0 3.0 5.5 V
Operating temperature TOPR - -40 +25 +85 °C
Storage temperature TSTG - -55 - +125 °C

Frequency characteristics

Item Symbol Conditions Rating Unit
Frequency tolerance Δ f/f Ta=+25°C
B: 5±23 *1)
AA: 5±5 *2)
AC: 0±5 *2)
Oscillation start-up time tSTA Ta=+25°C
1 Max. s
Frequency/voltage characteristics f/V Ta = +25°C
VDD=2.4V to 5.5V
±1 Max. ×10-6

*1 Equivalent to ±1 minute of monthly deviation (excluding offset.)
*2 Equivalent to ±13 seconds of monthly deviation (excluding offset.)

Current consumption characteristics

Ta=-40°C to +85°C

Item Symbol Conditions Min. Typ. Max. Unit
Current Consumption lBAT RX-8035SA
- 350 1200 nA
IDD VDD=3.0V SCL=SDA=GND CLKOUT=open - 1.40 2.50 µA

Power supply detection voltage

Ta=-40°C to +85°C

Item Symbol Condition Min. Typ. Max. Unit
VBAT detect voltage VLOW - 1.10 1.25 1.40 V
Power switching voltage
VD2B +25°C 2.328 2.40 2.472 V


Pin function

Signal Name Input/Output Functions
SCL Input I2C serial clock.
SDA In/Out I2C data in/out.
VDD - Main power supply.
VBAT - Power supply for backup.
Vout Output Switched power out.(maximum output current 20mA)
/ RES Output VDD voltage state.
GND - Ground
EVIN1 Input Event detection input 1
EVIN2 Input Event detection input 2
/ INTA Output Interrupt out A.
/ INTB Output Interrupt out B.
CLKOUT Output 32.768kHz output. (CMOS. Can not inhibit.)
N.C. - Do not connect.

Terminal connection / External dimensions

Terminal connection External dimensions

(Unit: mm)

Stop using the glue
Any glue must never use it after soldering LC-package to a circuit board.
This product has glass on the back side of a package.
When glue invasions between circuit board side and glass side, then glass cracks by thermal expansion of glue.
In this case a crystal oscillation stops.Consider glue abolition or glue do not touch to LC-package

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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