4-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC
S
WITH VOLTAGE MONITORING FUNCTION
R
×
5C348A/B
APPLICATION MANUAL
ELECTRONIC DEVICES DIVISION
NO.EA-054-9908
NOTICE
1. The products and the product specifications described in this application manual are subject to change or
discontinuation of production without notice for reasons such as improvement. Therefore, before deciding to
use the products, please refer to Ricoh sales representatives for the latest information thereon.
2. This application manual may not be copied or otherwise reproduced in whole or in part without prior written
consent of Ricoh.
3. Please be sure to take any necessary formalities under relevant laws or regulations before exporting or
otherwise taking out of your country the products or the technical information described herein.
4. The technical information described in this application manual shows typical characteristics of and example
application circuits for the products. The release of such information is not to be construed as a warranty of or a
grant of license under Ricoh's or any third party's intellectual property rights or any other rights.
5. The products listed in this document are intended and designed for use as general electronic components in
standard applications (office equipment, computer equipment, measuring instruments, consumer electronic
products, amusement equipment etc.). Those customers intending to use a product in an application requiring
extreme quality and reliability, for example, in a highly specific application where the failure or misoperation of
the product could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system, traffic
control system, automotive and transportation equipment, combustion equipment, safety devices, life support
system etc.) should first contact us.
6. We are making our continuous effort to improve the quality and reliability of our products, but semiconductor
products are likely to fail with certain probability. In order prevent any injury to persons or damages to property
resulting from such failure, customers should be careful enough to incorporate safety measures in their design,
such as redundancy feature, fire-containment feature and fail-safe feature. We do not assume any liability or
responsibility for any loss or damage arising from misuse or inappropriate use of the products.
7. Anti-radiation design is not implemented in the products described in this application manual.
8. Please contact Ricoh sales representatives should you have any questions or comments concerning the
products or the technical information.
June 1995
R
×
5C348A/B
APPLICATION MANUAL
CONTENTS
OUTLINE
......................................................................................................
1
FEATURES
..................................................................................................
1
BLOCK DIAGRAM
........................................................................................
2
APPLICATIONS
.............................................................................................
2
SELECTION GUIDE
.......................................................................................
2
PIN CONFIGURATION
...................................................................................
2
PIN DESCRIPTIONS
......................................................................................
3
ABSOLUTE MAXIMUM RATINGS
...................................................................
4
RECOMMENDED OPERATING CONDITIONS
.................................................
4
DC ELECTRICAL CHARACTERISTICS
...........................................................
5
AC ELECTRICAL CHARACTERISTICS
...........................................................
6
GENERAL DESCRIPTION
..............................................................................
7
FUNCTIONAL DESCRIPTIONS
......................................................................
9
1. Address Mapping
.........................................................................................
9
2. Register Settings
........................................................................................
10
USAGES
.....................................................................................................
22
1. Data Transfer Formats
2.
3.
4.
5.
6.
7.
8.
.................................................................................
22
Configuration of Oscillation Circuit and Correction of Time Count Deviations
.................
28
Oscillation Halt Sensing and Supply Voltage Monitoring
..........................................
33
Alarm and Periodic Interrupt
...........................................................................
35
32-kHz Clock Output
...................................................................................
38
Typical Applications
....................................................................................
39
Typical Characteristics
.................................................................................
42
Typical Software-based Operations
..................................................................
44
PACKAGE DIMENSIONS
.............................................................................
48
TAPING SPECIFICATIONS
...........................................................................
49
4-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC
S
WITH VOLTAGE MONITORING FUNCTION
R
×
5C348A/B
OUTLINE
The R
×
5C348A/B are CMOS real-time clock ICs connected to the CPU by four signal lines CE (Chip Enable),
SCLK (Serial Clock), SI (Serial Input), and SO (Serial Output) 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 R
×
5C348A and 0.55µA for the R
×
5C348B 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 for the R
×
5C348A but cannot be
disabled by any register settings for the R
×
5C348B. Both these models come in an ultra-compact 10-pin SSOP
(RS5C348A/B with a height of 1.25mm and a pin pitch of 0.5mm) and 10-pin SSOP-G(RV5C348A/B 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
) for the R
×
5C348A
• Only four signal lines (CE, SCLK, SI, and SO) required for connection to the CPU.
Maximum clock frequency of 2MHz (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 (Nch. open drain output) The R
×
5C348A is designed to disable 32-kHz clock output in
response to a command from the host computer and the R
×
5C348B is designed to keep 32-kHz output enabled.
• 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
• Built-in oscillation stabilization capacitors (C
G
and C
D
)
• CMOS process
• Selectable 12-hour and 24-hour mode settings
• High precision oscillation adjustment circuit
TYP. 0.55µA (MAX. 1.0µA) at 3 volts (at 25
˚C
) for the R
×
5C348B
• Ultra-compact 10-pin SSOP(RS5C348A/B) 10-pin SSOP-G(RV5C348A/B)
1
R
×
5C348A/B
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
ADDRESS
DECODER
ADDRESS
REGISTER
I/O
CONTROL
SCLK
SI
SO
CE
INTR
INTERRUPT CONTROL
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)
SELECTION GUIDE
Package
32-kHz clock output
RS5C348A
RS5C348B
RV5C348A
10-pin SSOP
(Pitch 0.5mm, Height 1.25mm, Size 6.4
×
3.5mm)
10-pin SSOP-G
Controllable by command
Keeping output enabled
Controllable by command
Keeping output enabled
PIN CONFIGURATION
Height 1.20mm, Size 4.0
×
2.9mm)
(Pitch 0.5mm,
RV5C348B
PIN CONFIGURATION
• 10-pin SSOP-G, 10-pin SSOP
32KOUT
SCLK
SO
SI
VSS
1
2
3
4
5
10
9
8
7
6
VDD
OSCIN
OSCOUT
CE
INTR
2
FPGA/CPLD
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