Skip to main content Skip to first level navigation

RICOH imagine. change.


Skip to main content First level navigation Menu
Main content


4-wire Serial Interface


Data Sheet

The Rx5C348A/B 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. 0.35μA at 3V: Rx5C348A, TYP.0.55μA 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 32.768kHz 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. These models come in an ultra-compact SSOP10 (RS5C348A/B), SSOP10G (RV5C348A/B), TSSOP10G (RT5C348B) (Limited)

  Package 32-kHz Clock Output
RS5C348A SSOP10 (Pin Pitch 0.5mm, Height1.25mm,6.4mm ×3.5mm) Controllable by command
Keeping output enabled
RV5C348A SSOP10G (Pin Pitch 0.5mm, Height1.2mm,4.0mm ×2.9mm) Controllable by command
RV5C348B Keeping output enabled
TSSOP10G (Pin Pitch 0.5mm, Height0.85mm,4.0mm ×2.9mm) Keeping output enabled


Timekeeping supply voltage ranging from 1.45 to 5.5V
Low power consumption
  • Rx5C348A: 0.35 µA TYP (0.8 µA MAX) at VDD=3V
  • RV5C348B: 0.55 µA TYP (1.0 µA MAX) at VDD=3V
Only four signal lines (CE, SCLK, SI, and SO) required for connection to the CPU.
Maximum clock frequency of 2MHz (with VDD=5V)
Time counters (counting hours, minutes, and seconds) and calendar counters (counting years, months, days, and weeks) (in BCD format)
Interrupt circuit configured to generate interrupt signals (with interrupts ranging from 0.5 seconds to 1 month) to the CPU and provided with an interrupt flag and an interrupt halt
2 alarm interrupt circuits (Alarm_W for week, hour, and minute alarm settings and Alarm_D for hour and minute alarm settings)
32-kHz clock output circuit (Nch. open drain output)
The Rx5C348A is designed to disable 32-kHz clock output in response to a command from the host computer and the Rx5C348B is designed to keep 32-kHz output enabled.
Oscillation halt sensing circuit which can be used to judge the validity of internal data
Supply voltage monitoring circuit with two supply voltage monitoring threshold settings
Automatic identification of leap years up to the year 2099
Selectable 12-hour and 24-hour mode settings
Built-in oscillation stabilization capacitors (CG and CD)
High precision oscillation adjustment circuit
Ultra-compact SSOP10 (RS5C348A), SSOP10G (RV5C348A/B)
CMOS process


  • Communication devices (multi function phone, portable phone, PHS or pager)
  • OA devices (fax, portable fax)
  • Computer (desk-top and mobile PC, portable word-processor, PDA, electric note or video game)
  • AV components (portable audio unit, video camera,camera, digital camera or remote controller)
  • Home appliances (rice cooker, electric oven)
  • Other (car navigation system, multi-function watch)

Documents Download

Data Sheet Package Info. Mark Info. Quality Assurance Data
Rx5C348A/B Series
SSOP-10 RS5C348A Reliability
SSOP-10G RV5C348A/B Reliability

All PDF files are less than 1MB unless otherwise stated.

Inquiry about products

Technical Support

Inquiries (SSL Form)

Inquiry about business

Purchase, Request for Samples and Documents


Sample Online

Online Distributors