Epson RA8804 CE Instructions for use

ETM60E-02
Preliminary
Application Manual
Real Time Clock Module
RA8804 CE

NOTICE
This 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 Seiko Epson.
The information about applied circuitry, software, usage, etc. written in this material is intended for
reference only. Seiko Epson does not assume any liability for the occurrence of infringing on any
patent or copyright of a third party. This material does not authorize the licensing for any patent or
intellectual copyrights.
When exporting the products or technology described in this material, you should comply with the
applicable export control laws and regulations and follow the procedures required by such laws and
regulations.
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 the applications stated below, you must
obtain permission from Seiko Epson 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.
All brands or product names mentioned herein are trademarks and/or registered trademarks of their
respective.

ETM60E Revision History
Rev No.
Date
Page
Description
ETM60E-01
30.Apr.2018
Release
ETM60E-02
27.Jun.2018
14
40
5) RESET bit
it explained detailed function of RESET.
8.15. Figure of 32 kHz-TCXO was updated.
SCL and SDA connects to GND.

RA8804 CE
ETM60E-02
Table of 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. Description of Registers.............................................................................................................................................6
8.1.1. Write/Read and Bank Select..........................................................................................................................6
8.1.2. Register table (Basic time and calendar register)...........................................................................................6
8.1.3. Register table (Time stamp, EVIN, SOUT, Timer)..........................................................................................7
8.1.4. Quick Reference ............................................................................................................................................7
8.2. Details of Registers....................................................................................................................................................8
8.2.1. Clock counter (SEC - HOUR).........................................................................................................................8
8.2.3. Alarm registers.............................................................................................................................................10
8.2.4. Fixed-cycle timer control registers................................................................................................................10
8.2.5. Extension register ........................................................................................................................................10
8.2.6. Flag register.................................................................................................................................................11
8.2.7. Control register.............................................................................................................................................13
8.3. Fixed-cycle Timer Interrupt Function .......................................................................................................................15
8.3.1. Diagram of fixed-cycle timer interrupt function.............................................................................................15
8.3.2. Related registers for function of fixed-cycle timer interruption......................................................................16
8.3.3. Timer register...............................................................................................................................................16
8.3.4. Fixed-cycle timer interrupt interval (example)...............................................................................................18
8.3.5. Fixed-cycle timer start timing........................................................................................................................18
8.4. EVIN Interrupt and Time stamp Function.................................................................................................................19
8.4.1. Diagram of EVIN interrupt function...............................................................................................................19
8.4.2. Operation example of Time-Stamp function.................................................................................................20
8.4.3. Related registers for EVIN Interrupt and Time stamp Function....................................................................20
8.5. SOUT Interrupt Function..........................................................................................................................................23
8.5.1. Operation example of SOUT function. .........................................................................................................23
8.5.2. Related registers for SOUT interrupt functions.............................................................................................24
8.6. Time Update Interrupt Function...............................................................................................................................25
8.6.1. Time update interrupt function diagram........................................................................................................25
8.6.2. Related registers for time update interrupt functions....................................................................................26
8.7. Alarm Interrupt Function..........................................................................................................................................27
8.7.1. Diagram of alarm interrupt function..............................................................................................................27
8.7.2. Related registers for Alarm interrupt function...............................................................................................28
8.7.3. Examples of alarm settings..........................................................................................................................29
8.8. About the interrupt function for operation /INT = “L”interrupt output.......................................................................30
8.9. Temperature compensation function. ......................................................................................................................30
8.9.1. Temperature compensation function............................................................................................................30
8.9.2. Related registers for temperature compensation function............................................................................30
8.10. Reading/Writing Data via the I2C Bus Interface.....................................................................................................31
8.10.1. Overview of I2C-BUS.................................................................................................................................31
8.10.2. System configuration..................................................................................................................................31
8.10.3. Starting and stopping I2C bus communications..........................................................................................32
8.10.4. Data transfers and acknowledge responses during I2C-BUS communications..........................................33
8.10.5. Slave address ............................................................................................................................................33
8.10.6. I2C bus protocol..........................................................................................................................................34
8.11. Backup and Recovery............................................................................................................................................35
8.12. About access at the time of backup return and Initial power supply ......................................................................36
8.13. Flow chart..............................................................................................................................................................37
8.14. Connection with Typical Microcontroller ................................................................................................................40
8.15. When used as a clock source (32 kHz-TCXO) ......................................................................................................40
9. External Dimensions/Marking Layout...................................................................................................... 41
9.1. RX8804CE..............................................................................................................................................................41
9.1.1. External dimensions.....................................................................................................................................41
9.1.2. Marking layout..............................................................................................................................................41
10. Application notes..................................................................................................................................... 42

RA8804 CE
Page - 1 ETM60E-02
I2C-Bus Interface Real-time Clock Module
RA8804 CE
Features built-in 32.768 kHz DTCXO.
Supports I2C-Bus's high speed mode (Up to 400 kHz)
Time -Stamp function with EVIN-Pin trigger.
Outputs to SOUT-Pin of each of detection Flag or others.
Alarm interrupt function for day, date, hour, and minute settings
Fixed-cycle timer interrupt function
244.14 µs to 32 years
Time update interrupt function
(Seconds, minutes)
Temperature compensated 32.768 kHz output with OE function
(FOE and FOUT pins)
Auto correction of leap years
(from 2000 to 2099)
Wide interface voltage range: 1.6 V to 5.5 V
Wide time-keeping voltage range:1.5 V to 5.5 V
Low current consumption: 0.35 µA / 3.0 V (Typ.)
AEC-Q100 compliant for automotive applications
1. Overview
This module is an I2C 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, 32.768 kHz output function, Time-stamp function with EVIN-pin trigger,
and. Programmable output function to SOUT-pin of detection Flag or others.
The devices in this module are fabricated via a C-MOS process for low current consumption, which enables
long-term battery back-up.
2. Block Diagram
INTERRUPTS
CONTROLLER
ALARM REGISTER
/ INT
BUS
INTERFACE
CIRCUIT
( 32.768 kHz )
CONTROL
REGISTER
DIVIDER
CLOCK
POWER
CONTROLLER
and
SDA
VDD
SCL
CALENDR
TIMER REGISTER
DTCXO
CONTROLLER
FOUT
FOUT
FOE
CONTROLLER
SOUT
SOUT
CONTROLLER
EVENT DETECTION
EVIN
CAPTURE
BUFFER
VDD
SYSTEM
CONTROLLER

RA8804 CE
Page - 2 ETM60E-02
3. Terminal description
3.1. Terminal connections
RA8804CE
1.
FOE
10.
/ INT
2.
VDD
9.
GND
3.
EVIN
8.
T2
4.
FOUT
7.
SDA
5.
SCL
6.
SOUT
3.2. Pin Functions
Signal
name
I/O
Function
SDA
I/O
This pin's signal is used for input and output of address, data, and ACK bits, synchronized
with the serial clock used for I2C 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.
SCL
Input
This is the serial clock input pin for I2C Bus communications.
FOUT
Output
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. (depend on FSEL bit)
When output is stopped, the FOUT pin = Hi-Z (high impedance).
FOE
Input
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.
/ INT
Output
This pin is used to output alarm signals, timer signals, time update signals, and other signals.
This pin is an open drain pin.
EVIN
Input
Trigger input terminal for time-stamps. Built in disconnectable Pull-up resistor.
SOUT
Output
SOUT is push-pull for the inside state output.
SOUT outputs state of a specified flag bit or selected logical 1 or 0.
VDD

This pin is connected to a positive power supply.
GND

This pin is connected to a ground.
T2

Use only for testing in the factory.
(Do not connect externally.)
Note: Be sure to connect a bypass capacitor rated at least 0.1 μF between VDD and GND.

RA8804 CE
Page - 3 ETM60E-02
4. Absolute Maximum Ratings
5. Recommended Operating Conditions
GND=0 V
Item
Symbol
Condition
Min.
Typ.
Max.
Unit
Operating supply voltage
VACC
Between VDD and GND
1.6
3.0
5.5
V
Temp. compensation voltage
VTEM

1.5
3.0
5.5
V
Clock supply voltage
VCLK

1.5
3.0
5.5
V
Operating temperature
TOPR
No condensation
40
+25
+105
C
* To apply Min. value of VACC and VCLK, the VDD needs to be supplied with more than 1.5 V at least for the oscillation to stabilize
(oscillation start time tSTA).
* The Min. value of VCLK is the Min. voltage required to retain the time counting function; it is however necessary to maintain VTEM till the
oscillation of the oscillator has stabilized (oscillation start time tSTA).
* The temperature compensation stops working below Min. value of VTEM.
6. Frequency Characteristics
GND=0V
Item
Symbol
Condition
Rating
Unit
Frequency stability
f/f
XA
Ta = 0 to +50 C, VDD = 3.0 V
Ta = -40 to +85 C, VDD = 3.0 V
Ta = -85 to +105 C, VDD = 3.0 V
1.9*1
3.4*2
8.0*3
10-6
XB
Ta = 0 to +50 C, VDD = 3.0 V
Ta = -40 to +85 C, VDD = 3.0 V
Ta = -85 to +105 C, VDD = 3.0 V
3.8*4
5.0*5
8.0*3
Frequency/voltage
characteristics
f/V
Ta= +25 C, VDD=1.5 V to 5.5 V
1.0 Max.
10-6/V
FOUT duty cycle
Duty
50% VDD
+25 C, VDD=1.5 V to 5.5 V
50 10
%
Oscillation start time
tSTA
Ta = +25 C, VDD = 1.5 V 5.5 V
Ta = -40 to +85 C, VDD = 1.6 V to 5.5 V
1.0 Max.
3.0 Max.
s
Aging
fa
Ta = +25 C, VDD = 3.0 V, first year
3 Max.
10-6/year
Reflow
fref
260 C (Max.), 2 times
3*6 Max.
10-6
*1 5 sec error per a month.
*2 9 sec error per a month.
*3 21 sec error per a month.
*4 10 sec error per a month.
*5 13.2 sec error per a month.
*6 The result that it was measured at 25

C, 24 hours after processing of reflow soldering.
GND=0V
Item
Symbol
Condition
Rating
Unit
Supply voltage
VDD
Between VDD and GND
0.3 to +6.5
V
Input voltage (1)
VIN1
FOE, SCL, SDA, EVIN pins
ND0.3 to +6.5
V
Input voltage (2)
VIN2
EVIN pin
GND0.3 to VDD+0.3
V
Output voltage (1)
VOUT1
FOUT and SOUT pin
GND0.3 to VDD+0.3
V
Output voltage (2)
VOUT2
SDA and /INT pins
GND0.3 to +6.5
V
Storage temperature
TSTG
When stored separately,
without packaging
55 to +125
C

RA8804 CE
Page - 4 ETM60E-02
7. Electrical Characteristics
7.1. DC Characteristics
*Unless otherwise specified, GND=0V,VDD=1.5Vto5.5V,Ta=40Cto+105C
Item
Symbol
Condition
Min.
Typ.
Max.
Unit
Average Current consumption(1)
IDD1
fSCL = 0 Hz. / INT = Hi-Z.
FOUT is stopped.
Temp compensation interval 2.0 s
VDD=5 V
0.40
1.6
µA
Average Current consumption(2)
IDD2
VDD=3 V
0.35
1.5
Average Current consumption(3)
IDD3
fSCL = 0 Hz. / INT = Hi-Z.
FOUT outputs 32 kHz. CL = 0 pF
Temp compensation interval 2.0 s
VDD=5 V
1.1
3.1
Average Current consumption(4)
IDD4
VDD=3 V
1.0
3.0
Average Current consumption(5)
IDD5
fSCL = 0 Hz. / INT = Hi-Z.
FOUT outputs 32 kHz. CL = 30 pF
Temp compensation interval 2.0 s
VDD=5 V
6.1
8.1
Average Current consumption(6)
IDD6
VDD=3 V
4.0
6.0
Average Current consumption(7)
IDD7
fSCL = 0 Hz. / INT = Hi-Z.
FOUT is stopped.
Temp compensation is stopped.
VDD=5 V
0.38
1.55
Average Current consumption(8)
IDD8
VDD=3 V
0.33
1.45
Peak Current consumption(1)
IDD9
fSCL = 0 Hz. / INT = VDD.
FOUT is stopped.
Temp compensation ON (peak)
VDD=5 V
55
100
Peak Current consumption (2)
IDD10
VDD=3 V
50
95
High-level input voltage
VIH1
SCL, SDA, FOE
0.8 VDD
5.5
V
VIH2
EVIN
0.8 VDD
VDD
Low-level input voltage
VIL
SCL, SDA, FOE, EVIN
GND 0.3
0.2 VDD
High-level output voltage
VOH1
FOUT, SOUT
VDD = 5 V, IOH = 1 mA
4.5
5.0
VOH2
VDD = 3 V, IOH = 1 mA
2.2
3.0
VOH3
VDD = 3 V, IOH = 100 µA
2.9
3.0
Low-level output voltage
VOL1
FOUT, SOUT
VDD = 5 V, IOL = 1 mA
GND
GND+0.5
VOL2
VDD = 3 V, IOL = 1 mA
GND
GND+0.8
VOL3
VDD = 3 V, IOL = 100 µA
GND
GND+0.1
VOL4
/ INT
VDD = 5 V, IOL = 1 mA
GND
GND+0.25
VOL5
VDD = 3 V, IOL = 1 mA
GND
GND+0.4
VOL6
SDA
VDD 2 V, IOL = 3 mA
GND
GND+0.4
Input leakage current
ILK
INPUT pins, VIN = VDD or GND
0.5
0.5
µA
Output leakage current
IOZ
Output pins, output voltage = VDD or GND
0.5
0.5
Pull-up Resistor
REVIN
EVIN
125
500
2000
kΩ
Detection voltage of VDET
VDET
VDD
1.41
1.45
1.49
V
Detection voltage of VLF
VLOW
VDD
0.9
1.0
1.2
Temperature compensation and consumption current
0.7 ms Temp compensation ON (peak)
IDD9,10
Temp Compensation interval (2.0 s)
IDD7,8
IDD1,2
Temp Compensation OFF
Average
The current consumption of RA8804 increases at a timing of a temperature compensation.
As for this peak current consumption, it occurs in about 0.7ms.
IDD1, IDD2 is the average current consumption at temperature compensation in 2 seconds cycle.

RA8804 CE
Page - 5 ETM60E-02
7.2. AC characteristics
* Unless otherwise specified, GND=0V,VDD=1.6Vto5.5V,Ta=40Cto+105C
Item
Symbol
Condition
SCL = 100 kHz
(Standard-Mode
SCL = 400 kHz
(Fast-Mode)
Unit
Min.
Max.
Min.
Max.
SCL clock frequency
fSCL


100

400
kHz
Start condition setup time
tSU;STA

4.7

0.6

µs
Start condition hold time
tHD;STA

4.0

0.6

µs
Data setup time
tSU;DAT

250

100

ns
Data hold time
tHD;DAT

0

0

ns
Stop condition setup time
tSU;STO

4.0

0.6

µs
Bus idle time between
start condition and stop condition
tBUF

4.7

1.3

µs
Time when SCL = ”L”
tLOW

4.7

1.3

µs
Time when SCL = “H”
tHIGH

4.0

0.6

µs
Rise time for SCL and SDA
tr


1.0

0.3
µs
Fall time for SCL and SDA
tf


0.3

0.3
µs
Allowable spike time on bus
tSP


50

50
ns
Timing chart
tHD ; DAT
tSU ; DAT
tHD ; STA
tLOW
tHIGH
1 / fSCL
tr
tf
tSU ; STA
SDA
SCL
START
CONDITION
(S)
BIT 7
MSB
(A7)
BIT 6
(A6)
ACK
(A)
Protocol
tBUF
tSU ; STO
STOP
CONDITION
(P)
START
CONDITION
(S)
(P)
(A)
tHD ; STA
tSU ; STA
(S)
BIT 0
LSB
(R/W)
(S)
tSP
Note:
1. As for the communication of I2C, completion of less than 1 second is recommended. If such
communication requires 1 second (Max.) or longer, the I2C bus interface is reset by the internal bus
timeout function. When bus-time-out occur, SDA turns to Hi-Z input mode.
2. But readout data of a clock is stable anytime, and there isn’t contradiction. And it does not occur
that data of a clock delay even if access time is prolonged.
Reference characteristic data (Typical) I2C-bus active current

RA8804 CE
Page - 6 ETM60E-02
8. Use Methods
8.1. Description of Registers
8.1.1. Write/Read and Bank Select
Address 00h to 0Fh: Basic time and calendar register. It compatible with RX-8803 and RX/RA8900
Address 10h to 1Fh: Extension register
Access to more than address 20h is possible, but there is some control register for quality inspection. When more than
Address auto increment is looping in lower 4 bits address.
Upper 4bits address are fixed. (00, ..., 0E, 0F, 00, 01) (10, ..., 1E, 1F, 10, 11)
Basic register
Time stamp register
Access is prohibited
Address (8bit)
0Fh from 00h
1Fh from 10h
FFh from 20h
8.1.2. Register table (Basic time and calendar register)
Address
Function
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
Init
Write
00
SEC

40
20
10
8
4
2
1

01
MIN

40
20
10
8
4
2
1

02
HOUR


20
10
8
4
2
1

03
WEEK

6
5
4
3
2
1
0

04
DAY


20
10
8
4
2
1

05
MONTH



10
8
4
2
1

06
YEAR
80
40
20
10
8
4
2
1

07
RAM









08
MIN Alarm
AE
40
20
10
8
4
2
1

09
HOUR Alarm
AE

20
10
8
4
2
1

0A
WEEK Alarm
AE
6
5
4
3
2
1
0

DAY Alarm

20
10
8
4
2
1
0B
Timer Counter 0
128
64
32
16
8
4
2
1

0C
Timer Counter 1
32768
16384
8132
4096
2048
1024
512
256

0D
Extension Register
TEST
WADA
USEL
TE
FSEL1
FSEL0
TSEL1
TSEL0
[0:2]

0E
Flag Register


UF
TF
AF

VLF
VDET
[0:0]
Clear
only
0F
Control Register
CSEL1
CSEL0
UIE
TIE
AIE


RESET
[4:0]

Writing is avoid. Read value is 0, always. It can read and write. is available. avoid.
“Init”shows value of after power-on Reset. Unit is Hex.
Note
After the initial power-up (from 0V) or in case the VLF bit returns “1”, make sure to initialize all registers, before
using the RTC.
Be sure to avoid entering incorrect date and time data, as clock operations are not guaranteed when the data or
time data is incorrect.
-
During the initial power-up,the following are the default settings for the register values
Initial value_0: TSVLF, TSVDET,TEST, WADA, USEL, TE, FSEL1, FSEL0, TSEL0, UF, TF, AF, CSEL1, UIE, TIE,
AIE, RESET, ECP, EHL, EPU, RCE, EIE, ET1, ET0, EF, EVMON, SOE0 ~ SOE7, DCE, DC, SRV,
FS0～FS2, TRES, TSTP, All bits of address 1Ch, 1Dh, 1Eh, and 1Fh.
Initial value_1: TSEL1, VLF,VDET,CSEL0
At this point, all other register values are undefined, so be sure to perform a reset before using the module.
-
Only a 0 can be written to the UF, TF, AF, VLF, VDET and EF bit.
The EVMON bit is read only bit.
-
Any bit marked with “”should be used with a value of “0”after initialization.
-
Any bit marked with “”is a RAM bit that can be used to read or write any data.
-
The TEST bit is used by the manufacturer for testing. Be sure to set “0”for this bit when writing.
-
If an alarm function is not used, registers 08h-0Ah can be used as RAM. (AIE : “0”)
-
Reading register value of address 0Bh-0Ch and 1Fh is pre-set data.
If a timer function is not used, register of 0Bh-0Ch and 1Fh can be used as RAM. (TE,TIE : “0”)