RX-8035SA (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)

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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