RTC-4543SB (Simple Function Serial-Interface Real Time Clock Module)

  • Built in frequency adjusted 32.768kHz crystal unit.
  • Interface Type
    3-wire serial interface
  • Operating voltage range
    2.5V to 5.5V
  • Wide Timekeeper voltage range
    1.4V to 5.5V
  • 32.768kHz frequency output function
    C-MOS output With Control Pin
  • The various functions include full calendar, timer, and low voltage detection.

Complies with EU RoHS directive.


Block diagram

Block diagram


  • 32.768kHz frequency output function
    • FOUT pin output (C-MOS output ), CL=30pF
    • FOE pin enables output on/off control.
    • FSEL pin enables output selectable 32.768kHz or 1 Hz.
  • Power supply voltage monitoring function
    • Detection that power supply voltage descended to 1.7V or less.
    • Automatic record to FDT-bit at the time of power supply decline detection.

Pin function

Signal Name Input/Output Function
CE Input The chip enabled input pin. At the HIGH level, access becomes possible.
CLK Input The shift clock input pin for serial data transfer.
WR Input DATA pin input / output switching pin.
DATA Bi-directional The data input / output pin for serial data transfer.
FOUT Output 32.768kHz or 1Hz clock output pin
(C-MOS output).
High impedance at output off.
FOE Input The input pin for the FOUT output control.
FSEL Input Select the frequency that is output from the FOUT pin.
VDD - Connected to a positive power supply.
GND - Connected to a ground.

Terminal connection / External dimensions

Terminal connection External dimensions

(Unit: mm)

Metal may be exposed on the top or bottom of this product. This will not affect any quality, reliability or electrical spec.

Specifications *Refer to application manual for details.

Recommend Operating Conditions

Item Symbol Condition Min. Typ. Max. Unit
Power voltage VDD - 2.5 5.0 5.5 V
Clock voltage VCLK - 1.4 5.0 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
5±23 * ×10-6
Oscillation start-up time tSTA Ta=+25°C
3Max. s

* Please ask for tighter tolerance.(Equivalent to ±1minute of monthly deviation )

Current consumption characteristics

*Ta=-40°C to +85°C

Item Symbol Conditions Min. Typ. Max. Unit

FOUT;output OFF(Hi-z)
VDD=5V 1.5 3.0 µA
VDD=3V 1.0 2.0
VDD=2V 0.5 1.0

Supply Voltage Detection Characteristic

Item Symbol Condition Min. Typ. Max. Unit
Power supply
detection voltage
VDT VDD pin 1.4 1.7 2.0 V
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