I
2
C bus SERIAL INTERFACE REAL-TIME CLOCK IC
WITH VOLTAGE MONITORING FUNCTION
RV5C387A
OUTLINE
NO.EA-080-0208
The RV5C387A is a CMOS real-time clock IC connected to the CPU by two signal, SCL and SDA, and configured to
perform serial transmission of time and calendar data to the CPU. 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 circuits
generate interrupt signals at preset times. The oscillation circuit is driven under constant voltage so that fluctuations
in oscillation frequency due to voltage are small and supply current is also small (TYP. 0.35µA for the RV5C387A at
3 volts). 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 (Nch. open drain) 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 crystal
oscillator. The 32-kHz clock circuit can be disabled by certain register settings. This model comes in an ultra-
compact 10-pin SSOP-G (with a height of 1.20mm and a pin pitch of 0.5mm).
FEATURES
• Timekeeping supply voltage ranging from 1.45 to 5.5 volts
• Low supply current: TYP. 0.35µA (MAX. 0.8µA) at 3 volts
• Only two signal lines (SCL, SDA) required for connection to the CPU.
(I
2
C bus compatible, 400kHz at V
DD
≥2.5V,
address 7bits)
• Time counters (counting hours, minutes, and seconds) and calendar counters (counting years, months, days,
and weeks) (in BCD format)
• 1900/2000 identification bit for Year 2000 compliance
• 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 circuit
• 2 alarm circuits (Alarm_W for week, hour, and minute alarm settings and Alarm_D for hour and minute
alarm settings)
• 32-kHz clock circuit (Nch. open drain output)
• Oscillation halt sensing circuit which can be used 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
• High precision oscillation adjustment circuit
• Built-in oscillation stabilization capacitors (C
G
and C
D
)
• CMOS process
• Ultra-compact 10-pin SSOP-G(with a height of 1.20mm and size 4.0mm
×
2.9mm)
1
RV5C387A
Note
· I
2
C bus is a trademark of PHILIPS ELECTRONICS N.V.
· Purchase of I
2
C components of Ricoh Company, Ltd. conveys a license under the Philips I
2
C Patent Rights to
use these components in an I
2
C system, provided that the system comforms to the I
2
C Standard
Specification as defined by Philips.
BLOCK DIAGRAM
32KOUT
32kHz
OUTPUT
CONTROL
COMPARATOR_W
ALARM_W REGISTER
(MIN,HOUR,WEEK)
VDD
COMPARATOR_D
OSCIN
OSC
OSCOUT
ALARM_D REGISTER
(MIN,HOUR)
VOLTAGE
DETECT
VSS
DIVIDER
CORREC
-TION
DIV
TIME COUNTER
(SEC,MIN,HOUR,WEEK,DAY,MONTH,YEAR)
OSC
DETECT
INTRA
ADDRESS
DECODER
ADDRESS
REGISTER
I/O
CONTROL
SCL
SDA
INTRB
INTERRUPT CONTROL
INTRC
SHIFT REGISTER
APPLICATIONS
• 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)
PIN CONFIGURATION
• 10-pin SSOP-G
32KOUT
SCL
SDA
INTRC
VSS
1
2
3
4
5
10
9
8
7
6
VDD
OSCIN
OSCOUT
INTRB
INTRA
2
RV5C387A
PIN DESCRIPTIONS
Pin No. Symbol
Item
Description
This pin is used to input shift clock pulses to synchronize data input/output to and
2
SCL
Serial Clock Line
from the SDA pin with this clock. Allows a maximum input voltage of 5.5 volts
regardless of supply voltage.
This pin inputs and outputs written or read data in synchronization with shift clock
3
SDA
Serial Data Line
pulses from the SCL pin. Allows a maximum input voltage of 5.5 volts regardless
of supply voltage.
6
INTRA
Interrupt Output A
This pin outputs periodic interrupt pulses to the CPU. This pin is off when power
is activated from 0V. This pin functions as an Nch open drain output.
This pin outputs alarm interrupt (ALARM_W) to the CPU. This pin is off when
power is activated from 0V. This pin functions as an Nch open drain output.
This pin outputs alarm interrupt (ALARM_D) to the CPU. This pin is off when
power is activated from 0V. This pin functions as an Nch open drain output.
The 32KOUT pin is used to output 32.768-kHz clock pulses. Enabled at power-on
1
9
8
10
5
32KOUT 32-kHz Clock Output
OSCIN
OSCOUT
VDD
VSS
Oscillatory Circuit
Input/Output
Positive Power Supply Input
Negative Power Supply Input
The VDD pin is connected to the power supply. The VSS pin is grounded.
from 0 volts. Nch. open drain output. The RV5C387A is designed to be disable 32-
kHz clock output in response to a command from the host computer.
The OSCIN and OSCOUT pins are used to connect the 32.768-kHz crystal
oscillator (with all other oscillation circuit components built into the RV5C387A).
7
INTRB
Interrupt Output B
4
INTRC
Interrupt Output C
3
RV5C387A
ABSOLUTE MAXIMUM RATINGS
(Vss=0V)
Symbol
Item
Conditions
Ratings
Unit
V
DD
V
I
V
O
P
D
Topt
Tstg
Supply Voltage
Input Voltage 2
Output Voltage
Power Dissipation
Operating Temperature
Storage Temperature
SCL, SDA
SDA, INTRA, INTRB
INTRC, 32KOUT
Topt=25˚C
–0.3 to +6.5
–0.3 to +6.5
–0.3 to +6.5
300
–40 to +85
–55 to +125
V
V
V
mW
˚C
˚C
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under
any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation
above these absolute maximum ratings may cause degradation or permanent damage to the device. These
are stress ratings only and do not necessarily imply functional operation below these limits.
RECOMMENDED OPERATING CONDITIONS
(Vss=0V,Topt=–40 to +85˚C)
Symbol
Item
Conditions
MIN.
TYP.
MAX.
Unit
V
DD
V
CLK
Supply Voltage
Timekeeping Voltage
Oscillation Frequency
Pull-up Voltage
SCL, SDA, INTRA, INTRB, INTRC, 32KOUT
2.0
1.45
32.768
5.5
5.5
V
V
kHz
f
XT
V
PUP
5.5
V
4
RV5C387A
DC ELECTRICAL CHARACTERISTICS
Unless otherwise specified : Vss=0V,V
DD
=3V,Topt=–40 to +85˚C
Symbol
Item
Pin name
Conditions
MIN.
TYP.
MAX.
Unit
V
IH
V
IL
I
OL1
I
OL2
I
OL3
I
IL
“H” Input Voltage
SCL,SDA
“L” Input Voltage
32KOUT
“L” Output Current
INTRA, INTRB, INTRC V
OL
=0.4V
SDA
Input Leakage Current SCL
SDA, INTRA, INTRB
INTRC
V
I
=5.5V or Vss
V
DD
=5.5V
Vo=5.5V or Vss
V
DD
=5.5V
V
DD
=3V,
SCL=SDA=3V,
V
DD
=2.5 to 5.5V
0.8V
DD
–0.3
0.5
1.0
4.0
–1
5.5
0.2V
DD
V
mA
1
µA
I
OZ
–1
1
µA
I
DD
VDD
Output=OPEN
32KOUT=OFF mode
*
1
0.35
0.8
µA
V
DETH
Supply Voltage Monitoring
Voltage (“H”)
Supply Voltage Monitoring
Voltage (“L”)
VDD
VDD
Topt=–30 to +70˚C
1.90
2.10
2.30
V
V
DETL
C
G
C
D
Topt=–30 to +70˚C
1.45
1.60
12
1.80
V
Internal Oscillation Capacitance 1 OSCIN
Internal Oscillation Capacitance 2 OSCOUT
pF
12
*
1)
For standby current for outputting 32.768-kHz clock pulses from the 32KOUT pin, see “USAGES, 7. Typical Characteristics”.
5
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