2 wire interface Real-Time Clock ICs
Description
R2051 SERIES
2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
NO.
EA-104-070626
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OUTLINE
The R2051 is a CMOS real-time clock IC connected to the CPU by two signal lines, SCL and SDA, and configured to perform serial transmission of time and calendar data to the CPU.
Further, battery backup switchover circuit and a voltage detector are incorporated.
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.
4µA at 3V).
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 (CMOS output) is intended to output sub-clock pulses for the external microcomputer.
The oscillation adjustment circuit is intended to adjust time counts with high precision by correcting deviations in the oscillation frequency of the quartz crystal unit.
Battery backup switchover function is the automatic switchover circuit between a main power supply and a backup battery of primary or secondary battery.
Switchover is executed by monitoring the voltage of a main power supply, therefore the voltage of a backup battery voltage is not relevant.
Since the package for these ICs is SSOP16 (5.
0x6.
4x1.
25: R2051Sxx), FFP12 (2.
0x2.
0x1.
0: R2051Kxx), or TSSOP10G (4.
0x2.
9x1.
0: R2051Txx), high density mounting of ICs on boards is possible.
FEATURES
• • • • • • • • • • • • • • • • • Minimum Timekeeping supply voltage Typ.
0.
75V (Max.
1.
00V); VDD pin Low power consumption 0.
4µA TYP (1.
0...
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