I2C bus SERIAL INTERFACE REAL-TIME CLOCK ICs

 

 

OUTLINE

The RS5C372A 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 RS5C372A 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. (Nch. open drain 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

RS5C372A is the optimum choice for equipment requiring small sized and low power consuming products.

 

 

 

FEATURES

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) (INTRA, INTRB)

Two systems of alarm functions (days of the week, hours, and minutes) (INTRA, INTRB)

Oscillation halt sensing to judge internal data validity

Clock output of 32.768kHz (32.000kHz) (output controllable via a register) 

...

(Nch. open drain 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