3-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC
S
WITH VOLTAGE MONITORING FUNCTION
R
×
5C338A
OUTLINE
NO. EA-053-170413
The R
×
5C338A are CMOS real-time clock ICs connected to the CPU by three signal lines CE (Chip Enable), SCLK
(Serial Clock), and SIO (Serial Input/Output), and configured to perform serial transmission of time and calendar
data to the CPU. These models incorporate different functional circuits. 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 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 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. These models come in
an ultra-compact 10-pin SSOP (RS5C338A with a height of 1.25mm and a pin pitch of 0.5mm)and 10-pin SSOP-G
(RV5C338A with a height of 1.2mm 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 (at 25˚C)
• Only three signal lines (SCLK, SIO, and CE) required for connection to the CPU.
Maximum clock frequency of 2 MHz (with V
DD
of 5 volts)
• 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 (CMOS output, equipped with a control pin)
• 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 (RS5C338A with a height of 1.25mm and size of 6.4
×
3.5mm)
Ultra-compact 10-pin SSOP-G (RV5C338A with a height of 1.20mm and size of 4.0
×
2.9mm)
1
R
×
5C338A
BLOCK DIAGRAM
32KOUT
CLKC
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
ADDRESS
DECODER
ADDRESS
REGISTER
I/O
CONTROL
SCLK
SIO
INTR
INTERRUPT CONTROL
SHIFT REGISTER
CE
SELECTION GUIDE
Part Number is designated as follows:
R V 5C338A - E2 - F
←Part
Number
↑
↑ ↑
R a 5C338A - bb – c
Code
a
bb
c
Designation of the package.
S: SSOP10 V: SSOP10G
Description
Designation of the taping type. Only E2 is available.
Designation of the lead plating.
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)
2
R
×
5C338A
PIN CONFIGURATION
• 10-pin SSOP-G, 10-pin SSOP
32KOUT
SCLK
SIO
CE
VSS
1
2
3
4
5
10
9
8
7
6
VDD
OSCIN
OSCOUT
CLKC
INTR
PIN DESCRIPTIONS
Pin No. Symbol
Name
Description
The CE pin is used for interfacing with the CPU. Should be held high to allow
4
CE
Chip Enable Input
access to the CPU. Incorporates a pull-down resistor. Should be held low or open
when the CPU is powered off. Allows a maximum input voltage of 5.5 volts regard-
less of supply voltage.
The SCLK pin is used to input clock pulses synchronizing the input and output of
2
SCLK
Serial Clock Input
data to and from the SIO pin. Allows a maximum input voltage of 5.5 volts regard-
less of supply voltage.
3
SIO
Serial Input/Output
The SIO pin is used to input and output data intended for writing and reading in
synchronization with the SCLK pin. CMOS input/output.
The INTR pin is used to output periodic interrupt signals to the CPU and alarm
6
INTR
Interrupt Output
interrupt signals (Alarm_W, Alarm_D). Disabled at power-on from 0 volts.
Nch. open drain output.
The 32KOUT pin is used to output 32.768-kHz clock pulses. Enabled at power-on
1
32KOUT 32-kHz Clock Output from 0 volts. CMOS output. This pin is disabled if the CLKC pin is set to low or
open.
The CLCK pin is used to control output of the 32KOUT pin. The clock output is
7
CLKC
Clock Control Input disabled and held low when the pin is set to low or open. Incorporates a pull-down
resistor.
9
8
10
5
OSCIN
OSCOUT
VDD
VSS
Oscillation Circuit
Input/Output
Positive Power Supply Input
Negative Power Supply Input
The OSCIN and OSCOUT pins are used to connect the 32.768-kHz crystal oscilla-
tor (with all other oscillation circuit components built into the R
×
5C338A.)
The VDD pin is connected to the power supply. The VSS pin is grounded.
3
R
×
5C338A
ABSOLUTE MAXIMUM RATINGS
Symbol
Item
Conditions
Ratings
(Vss=0V)
Unit
V
DD
V
I
Supply Voltage
Input Voltage 1
Input Voltage 2
Output Voltage 1
SIO
SCLK, CE,CLKC
SIO, 32KOUT
INTR
Topt=25˚C
–0.3 to +6.5
–0.3 to V
DD
+0.3
V
V
–0.3 to +6.5
–0.3 to V
DD
+0.3
V
–0.3 to +6.5
300
–40 to +85
–55 to +125
mW
˚C
˚C
V
O
Output Voltage 2
P
D
Topt
Tstg
Power Dissipation
Operating Temperature
Storage Temperature
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
Symbol
Item
Conditions
MIN.
(Vss=0V,Topt=–40 to +85˚C)
TYP.
MAX.
Unit
V
DD
V
CLK
Supply Voltage
Timekeeping Voltage
Oscillation Frequency
Pull-up Voltage
INTR
2.0
1.45
32.768
5.5
5.5
V
V
kHz
f
XT
V
PUP
5.5
V
4
R
×
5C338A
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
IH1
V
IH2
V
IL
I
OH
I
OL1
“H” Input Voltage
“H” Input Voltage
“L” Input Voltage
“H” Output Current
”L” Output Current
SCLK,CE,CLKC
SIO
SCLK,CE,SIO,CLKC
SIO,32KOUT
INTR
SIO,32KOUT
V
OH
=V
DD
–0.5V
V
OL
=0.4V
V
OL
=0.4V
V
I
=5.5V or Vss
V
DD
=5.5V
V
DD
=2.5 to 5.5V
0.8V
DD
0.8V
DD
–0.3
5.5
V
DD
+0.3
0.2V
DD
–0.5
mA
mA
V
2
0.5
–1
40
120
0.35
1
400
1.0
µA
kΩ
µA
I
OL2
I
IL
R
DNCE
I
CLKC
Input Leakage Current SCLK
Pull-down Resistance
Pull-down Resistance
Input Current
Output Off-state
Leakage Current
CE
CLKC
I
OZ1
I
OZ2
SIO
INTR
Vo=5.5V or Vss
V
DD
=5.5V
V
O
=5.5V
V
DD
=3V,CE=OPEN
–1
–1
1
µA
1
I
DD1
Standby Current
V
DD
Output=OPEN
32KOUT=Off mode*
1
0.35
0.8
µA
V
DETH
Supply Voltage Monitoring
Voltage (“H”)
Supply Voltage Monitoring
Voltage (“L”)
V
DD
Topt=–30 to +70˚C
1.90
2.10
2.30
V
V
DETL
C
G
C
D
V
DD
Topt=–30 to +70˚C
1.45
1.60
12
12
1.80
V
Internal Oscillation Capacitance 1 OSCIN
Internal Oscillation Capacitance 2 OSCOUT
pF
*
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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