ETM25E-01
Application Manua
l
Real Time Clock Module
RX-8025T
NOTICE
• The material is subject to change without notice.
• Any part of this material may not be reproduced or duplicated in any form or any means without the written
permission of Epson Toyocom.
• The information, applied circuit, program, usage etc., written in this material is just for reference.
Epson Toyocom does not assume any liability for the occurrence of infringing any patent or copyright
of a third party. This material does not authorize the licensing for any patent or intellectual copyrights.
• Any product described in this material may contain technology or the subject relating to strategic
products under the control of the Foreign Exchange and Foreign Trade Law of Japan and may require an
export licence from the Ministry of International Trade and industry or other approval from another
government agency.
• You are requested not to use the products (and any technical information furnished, if any) for the
development and/or manufacture of weapon of mass destruction or for other military purposes.
You are also requested that you would not make the products available to any third party who may
use the products for such prohibited purposes.
• These products are intended for general use in electronic equipment. When using them in specific
applications that require extremely high reliability such as applications stated below, it is required to
obtain the permission from Epson Toyocom in advance.
/ Space equipment (artificial satellites, rockets, etc) / Transportation vehicles and related (automobiles,
aircraft, trains, vessels, etc) / Medical instruments to sustain life / Submarine transmitters
/ Power stations and related / Fire work equipment and security equipment / traffic control equipment
/ and others requiring equivalent reliability.
• In this manual for Epson Tyocom, product code and marking will still remain as previously
identified prior to the merger.Due to the on going strategy of gradual unification of part numbers, please
review product code and marking as they will change during the course of the coming months.
We apologize for the inconvenience, but we will eventually have a unified part numbering system
for Epson Toyocom which will be user friendly.
RX - 8025T
Contents
1. Overview
...................................................................................................................1
2. Block Diagram
........................................................................................................1
3. Terminal description
.............................................................................................2
3.1. Terminal connections
........................................................................................................ 2
3.2. Pin Functions
....................................................................................................................... 2
4. Absolute Maximum Ratings
...............................................................................3
5. Recommended Operating Conditions
............................................................3
6. Frequency Characteristics
..................................................................................3
7. Electrical Characteristics
.....................................................................................4
7.1. DC Characteristics
............................................................................................................. 4
7.2. AC Characteristics
.............................................................................................................. 5
8. Use Methods
...........................................................................................................6
8.1. Overview of Functions
....................................................................................................... 6
8.2. Description of Registers
.................................................................................................... 7
8.3. Fixed-cycle Timer Interrupt Function
........................................................................... 14
8.4. Time Update Interrupt Function
.................................................................................... 17
8.5. Alarm Interrupt Function
................................................................................................. 19
8.6. Reading/Writing Data via the I
2
C Bus Interface
........................................................ 22
8.7. Backup and Recovery
..................................................................................................... 26
8.8. Connection with Typical Microcontroller
..................................................................... 27
8.9. When used as a clock source (32 kHz-TCXO)
......................................................... 27
9. External Dimensions / Marking Layout
.........................................................28
9.1. External dimensions
........................................................................................................ 28
9.2. Marking layout
................................................................................................................... 28
10. Application notes
...............................................................................................29
10.1. Notes on handling
.......................................................................................................... 29
10.2. Notes on packaging
....................................................................................................... 29
RX – 8025T
I
2
C-Bus Interface Real-time Clock Module
RX
−
8025T
•
•
•
•
•
•
•
•
•
•
Features built-in 32.768 kHz DTCXO, High Stability.
Supports I
2
C-Bus's high speed mode (400 kHz)
Alarm interrupt function for day, date, hour, and minute settings
Fixed-cycle timer interrupt function
(Seconds, minutes)
Time update interrupt function
32.768 kHz output with OE function (FOE and FOUT pins)
(from 2000 to 2099)
Auto correction of leap years
Wide interface voltage range:
1.6 V to 5.5 V
Wide time-keeping voltage range:
1.2 V to 5.5 V
Low current consumption:
0.8
µ
A / 3 V (Typ.)
The I C-BUS is a trademark of NXP Semiconductors.
2
1. Overview
This module is an I C bus interface-compliant real-time clock which includes a 32.768 kHz DTCXO.
In addition to providing a calendar (year, month, date, day, hour, minute, second) function and a clock
counter function, this module provides an abundance of other functions including an alarm function,
fixed-cycle timer function, time update interrupt function, and 32.768 kHz output function.
The devices in this module are fabricated via a C-MOS process for low current consumption, which enables
long-term battery back-up.
All of these many functions are implemented in a SOP package.
2
2. Block Diagram
32.768 kHz
32kHz
DTCXO
DIVIDER
CLOCK
and
CALENDAR
FOUT
FOE
FOUT
CONTROLLER
TIMER
REGISTER
/ INT
INTERRUPT
CONTROLLER
ALARM
REGISTER
SCL
SDA
I2C-BUS
INTERFACE
CIRCUIT
CONTROL
REGISTER
and
SYSTEM
CONTROLLER
Page - 1
ETM25E-01
RX – 8025T
3. Terminal description
3.1. Terminal connections
RX
−
8025T
1. T1 (CE)
2. SCL
3. FOUT
4. N.C.
5. TEST
6. V
DD
7. FOE
SOP
−
14pin
14. N.C.
13. SDA
12. T2 (V
PP
)
11. GND
10. / INT
9. N.C.
8. N.C.
3.2. Pin Functions
Signal
name
T1(CE)
SCL
I/O
Input
Input
Function
* Use by the manufacture for testing. ( Do not connect externally.)
This is the serial clock input pin for I C Bus communications.
This is the C-MOS output pin with output control provided via the FOE pin.
When FOE = "H" (high level), this pin outputs a 32.768 kHz signal.
When output is stopped, the FOUT pin = "Hi-Z"( high impedance ).
* Use by the manufacture for testing. ( Do not connect externally.)
This pin is connected to a positive power supply.
This is an input pin used to control the output mode of the FOUT pin.
When this pin's level is high, the FOUT pin is in output mode. When it is low, output via
the FOUT pin is stopped.
This pins is used to output alarm signals, timer signals, time update signals, and other
signals. This pin is an open drain pin.
This pin is connected to a ground.
* Use by the manufacture for testing. ( Do not connect externally.)
This pin's signal is used for input and output of address, data, and ACK bits,
2
synchronized with the serial clock used for I C communications.
Since the SDA pin is an N-ch open drain pin during output, be sure to connect a suitable
pull-up resistance relative to the signal line capacity.
This pin is not connected to the internal IC.
Leave N.C. pins open or connect them to GND or V
DD
.
2
FOUT
Output
TEST
V
DD
Input
−
Input
FOE
/ INT
GND
T2(V
PP
)
Output
−
−
SDA
I/O
N.C.
−
Note: Be sure to connect a bypass capacitor rated at least 0.1 µF between V
DD
and GND.
Page - 2
ETM25E-01
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