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Data Sheet

The RS5C372B is a CMOS type real-time clock which is connected to the CPU via 2-wires and capable of serial transmission of clock and calendar data to the CPU.
The RS5C372B can generate various periodic interrupt clock pulses lasting for long period (one month), and alarm interrupt can be made by days of the week, hours, and minutes by two incorporated systems. Since an oscillation circuit is driven at a constant voltage, it undergoes fluctuations of few voltage and consequently offers low current consumption (Typ. 0.5μA at 3V). It also provides an oscillator halt sensing function applicable for data validation at power-on and other occasions and 32-kHz clock output for an external micro computer. (CMOS output) The product also incorporates a time trimming circuit that adjusts the clock with higher precision by adjusting any errors in crystal oscillator frequencies based on signals from the CPU. The crystal oscillator may be selected from 32.768kHz or 32.000kHz types. Integrated into an ultra compact and ultra thin 8 pin SSOP package, the RS5C372B is the optimum choice for equipment requiring small sized and low power consuming products.


Time keeping voltage 1.45V to 6.0V
Lowest supply current 0.5µA TYP. (0.9µA MAX.) : 3V (25°C)
(1.0µA MAX.) : 3V (-40 to +85°C)
Connected to the CPU via only 2-wires (I2C bus Interface, MAX.400kHz, address 7bit)
A clock counter (counting hours, minutes, and seconds) and a calendar counter (counting leap years, years, months, days, and days of the week) in BCD codes
Interrupt to the CPU (period of one month to one second, interrupt flag, interrupt halt function) (INTR)
Two systems of alarm functions (days of the week, hours, and minutes) (INTR)
Oscillation halt sensing to judge internal data validity
Clock output of 32.768kHz (32.000kHz)
(output controllable via a register)
(CMOS output)
Second digit adjustment by ±30 seconds
Automatic leap year recognition up to the year 2099
12-hour or 24-hour time display selectable
Oscillation stabilizing capacity (CG, CD) incorporated
High precision time trimming circuit
Oscillator of 32.768kHz or 32.000kHz may be used
CMOS logic
Package 8pin SSOP


  • 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
RS5C372A/B (7P-) SSOP-8 RS5C372A/B Reliability

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

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