RX-4045NB (High-Stability Frequency)

  • Built-in 32.768 kHz crystal unit
  • Frequency adjusted for high accuracy.
  • Interface Type
    4-Wire SPI
  • Operating voltage range
    1.7V to 5.5V
  • Wide Timekeeper voltage range
    1.15V to 5.5V
  • Low backup current
    0.48 mA / 3 V (Typ.)
  • Various detection Functions
    Oscillation stop detection function etc.
  • 32.768 kHz clock frequency output : N-ch open drain output
  • Function of time and calendar, the various detection function,
    and interrupt function etc.

Complies with EU RoHS directive.


Block diagram

Block diagram


  • Features built-in 32.768 kHz crystal unit.
    • Frequency adjusted for high accuracy
      (Equivalent to ±13 seconds of monthly deviation )
  • The various detection Function
    • Power supply voltage monitoring function (with selectable detection threshold).
    • Stop detection function.
    • Power-on reset detection function.
  • Equipped with alarm and timer
    • Timer function produces a periodic interruption signal.As for the Alarm function an optional combination is produced. (Date of the week , time , minute)

Specifications(characteristics) Refer to application manual for details.

Recommend Operating Conditions

Item Symbol Condition Min. Typ. Max. Unit
Power voltage VDD - 1.7 3.0 5.5 V
Cloak voltage VCLK - 1.15 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 VDD=3.0V AA:5±5 *1)
AA:0±5 *2)
start-up time
TSTA Ta=+25°C VDD=2.0V 1 Max. s
f/V Ta=+25°C VDD=2.0V to 5.5V ±1 Max. ×10-6

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

Current consumption characteristics

*Ta=-40°C to +85°C

Item Symbol Condition Min. Typ. Max. Unit
Current Consumption lBK CE=GND
FOUT;Output OFF(Hi-z)
VDD=5V - 0.60 1.80 µA
VDD=3V - 0.48 1.20
Output ON
VDD=3V - 0.65 2.00 µA

Power supply detection voltage

*Ta=-30°C to +70°C

Item Symbol Condition Min. Typ. Max. Unit
High-voltage mode VDETH VDD pin 1.90 2.10 2.30 V
Low-voltage mode VDETL VDD pin 1.15 1.30 1.45 V


Pin function

CE Input The chip enabled input pin. (built-in pull-down resistance) At the "H"level, access becomes possible.
CLK Input The shift clock input pin for serial data transfer.
Dl Input The data input pin for serial data transfer.
DO Output The data output pin for serial data transfer.
FOUT Output 32.768 kHz clock output pin with the output control function ( N-ch open drain ) High impedance at the time of output off.
/INT Output Interrupt output  ( N-ch open drain )
TEST - * Used by the manufacturer for testing. (Do not connect externally.)
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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