2 wire interface Real-Time Clock ICs with Battery Backup switch-over Function
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 ( 5.0 x 6.4 x 1.25 :
R2051Sxx ) , FFP12 (2.0 x 2.0 x 1.0 : R2051Kxx ) , or TSSOP10G ( 4.0 x 2.9 x 1.0 : R2051Txx ) , high density mounting of
ICs on boards is possible. |
|
 Minimum
Timekeeping supply voltage |
Typ. 0.75V (Max. 1.00V); VDD pin |
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| Low
power consumption |
0.4µA TYP (1.0µA MAX.) at VDD=3V |
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| Built-in
Backup switchover circuit (can be used for a primary battery, a secondary battery, or an electric double layer
capacitor) |
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| Only
two signal lines (SCL and SDA) required for connection to the CPU. ( I2C-Bus Interface, 400kHz) |
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| Time
counters (counting hours, minutes, and seconds) and calendar counters (counting years, months, days,and weeks)
(in BCD format) |
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| 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 (except R2051Txx) |
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| 2
alarm interrupt circuits (Alarm_W for week, hour, and minute alarm settings and Alarm_D for hour and minute
alarm settings) (except R2051Txx) |
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| Built-in
voltage detector with delay |
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| With
Power-on flag to prove that the power supply starts from 0V |
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| 32-kHz
clock output pin (CMOS output. "H" level is always equal to VCC.) |
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| Supply
voltage monitoring circuit with two supply voltage monitoring threshold settings |
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| Automatic
identification of leap years up to the year 2099 |
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| Selectable
12-hour and 24-hour mode settings |
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| High
precision oscillation adjustment circuit |
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| Built-in
oscillation stabilization capacitors (CG and CD) |
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| CMOS
process |
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| Package |
SSOP16 (5.0mm x 6.4mm x 1.25mm : R2051Sxx), FFP12 (2.0mm x 2.0mm x 1.0mm
: R2051Kxx), TSSOP10G (4.0x2.9x1.0: R2051Txx) |
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Communication devices (multi function phone, portable phone, PHS or pager) |
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OA devices (fax, portable fax)
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Computer (desk-top and mobile PC, portable word-processor, PDA, electric note or video
game) |
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AV components (portable audio unit, video camera,camera, digital camera or remote controller) |
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Home appliances (rice cooker, electric oven) |
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Other (car navigation system, multi-function watch) |
| * All PDF files are less than 1MB unless otherwise stated. |
| * If you don't have Adobe Reader, you can download free. |
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Product Catalog
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| Selection guide is available for download in PDF format. |
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R2051S/K/T
Series
