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Rx5C348 Series
4-wire Serial Interface Real Time Clock (RTC)

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  • Description

    The Rx5C348 are CMOS real-time clock ICs connected to the CPU by four signal lines, CE, SCLK, SI, SO, and configured to perform serial transmission of time and calendar data to the CPU. The periodic interrupt circuit is configured to generate interrupt signals with six selectable interrupts ranging from 0.5 seconds to 1 month. The 2 alarm interrupt circuits generate interrupt signals at preset times. As the oscillation circuit is driven under constant voltage, fluctuation of the oscillator frequency due to supply voltage is small, and the time keeping current is small (TYP. 0.35 µA at 3V: Rx5C348A, TYP. 0.55 µA at 3V: Rx5C348B). The oscillation halt sensing circuit can be used to judge the validity of internal data in such events as power-on; The supply voltage monitoring circuit is configured to record a drop in supply voltage below two selectable supply voltage monitoring threshold settings. The 32.768 kHz clock output function (N-channel open drain output) is intended to output sub-clock pulses for the external microcomputer. The 32-kHz clock circuit can be disabled by certain register settings for the Rx5C348A but cannot be disabled by any register settings for the Rx5C348B. The oscillation adjustment circuit is intended to adjust time counts with high precision by correcting deviations in the oscillation frequency of the crystal oscillator. SSOP10 and SSOP10G packages are available.

  • Spec
    Timekeeping Supply Voltage Range 1.45 V to 5.50 V
    Supply Current Rx5C348A: 0.35 µA (VDD = 3 V)
    Rx5C348B: 0.55 µA (VDD = 3 V)
    Connection to CPU Four Signal Lines (SCLK, SI, SO, CE), Serial Interface, Maximum Clock Frequency: 2 MHz (VDD = 5 V)
    Clock Output 32.768 kHz
    Rx5C348A: Nch Open Drain Output Controllable by Command
    Rx5C348B: Nch Open Drain Output Keeping Output Enable
    Package Rx5C348A: SSOP10, SSOP10G
    Rx5C348B: SSOP10G

    Protections / Functions

    ECO Clock Adjust OSC Halt Sensing Supply Voltage Monitoring Circuit Automatic Identification of Leap Years Selectable 12-hour and 24-hour Backup Switch
  • Technical
  • Quality &
    • Refer to the datasheets for the details on the product.
    • The package file or the datasheet includes package dimensions, taping specifications, taping reels dimensions, power dissipations, and recommended land pattern.

Download Datasheet

Functional Description

ECO ECO Function
Clock Adjust Clock Adjust Function
OSC Halt Sensing OSC Halt Sensing Function
Supply Voltage Monitoring Circuit Supply Voltage Monitoring Function
Automatic Identification of Leap Years Automatic Identification of Leap Years
Selectable 12-hour and 24-hour Selectable 12-hour and 24-hour
Built-in VD with Delay Time Built-in VD with Delay Time

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Category:Real Time Clock

Interface 4-wire
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Current (µA)
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Voltage min (V)
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Voltage max (V)