R2025S/D
High precision I
2
C-Bus Real-Time Clock Module
NO.EA-135-0603
OUTLINE
The R2025S/D is a real-time clock module, built in CMOS real-time clock IC and crystal oscillator, 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. The oscillation frequency is adjusted to high precision (0±5ppm: 15sec. per month at 25°C) 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. 0.48µA 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-kHz 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 by correcting deviations in the oscillation frequency of the crystal
oscillator.
FEATURES
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Built in 32.768kHz crystal unit, The oscillation frequency is adjusted to high precision (0±5ppm: at 25°C)
Time keeping voltage 1.15V to 5.5V
Super low power consumption 0.48µA TYP (1.2µA MAX) at VDD=3V
I2C-Bus interface (Maximum serial clock frequency: 400KHz at VDD≥1.7V)
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)
32768Hz Clock CMOS push-pull output with control pin
With Power-on flag to prove that the power supply starts from 0V
With Oscillation halt sensing Flag 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
Oscillation adjustment circuit for correcting temperature frequency deviation or offset deviation
CMOS process
Two types of package, SOP14(10.1x7.4x3.1) or SON22(6.1x5.0x1.3)
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R2025S/D
PIN DESCRIPTION
Symbol
SCL
Item
Serial
Clock Line
Serial
Data Line
Interrupt
Output A
Interrupt
Output B
32K Clock
Output
Description
The SCL pin is used to input clock pulses synchronizing the input and
output of data to and from the SDA pin. Allows a maximum input
voltage of 5.5 volts regardless of supply voltage.
The SDA pin is used to input or output data intended for writing or
reading in synchronization with the SCL pin. Up to 5.5v beyond VDD
may be input. This pin functions as an N-ch open drain output.
The /INTRA pin is used to output alarm interrupt (Alarm_D) and output
periodic interrupt signals to the CPU signals. Disabled at power-on
from 0V. N-ch. open drain output.
The /INTRA pin is used to output alarm interrupt (Alarm_W) and output
periodic interrupt signals to the CPU signals. Disabled at power-on
from 0V. N-ch. open drain output.
The 32KOUT pin is used to output 32.768-kHz clock pulses. Enabled
at power-on from 0 volts. CMOS output. The output is disabled and
held “L” when CLKC pi set to “L” or open, or certain register setting.
This pin is enabled at power-on from 0v.
The CLKC pin is used to control output of the 32KOUT pin. The clock
output is disabled and held low when the pin is set to low or open.
Incorporates a pull-down resistor.
The VDD pin is connected to the power supply.
The VSS pin is grounded.
This pin is power pin for testing in the factory. Don’t connect to any lines.
These pins are not connected to internal IC chip.
In R2025D (SON22), N.C. pins from 14 pin to 22 pin are connected
together internally. Never connect these pins to any lines, or connect to
VDD or VSS. And never connect different voltage level lines each other.
SDA
/INTRA
/INTRB
32KOUT
CLKC
Clock control
input
Positive Power
Supply Input
Negative Power
Supply Input
Test input
No Connection
VDD
VSS
VPP
N.C.
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