MQ442-01
Application Manua
l
Real Time Clock Module
RX-4045SA / NB
Model Product Number
RX-4045SA Q41404551xxxx00
RX-4045NB Q41404591xxxx00
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 Seiko Epson.
• The information, applied circuit, program, using way etc., written in this material is just for reference.
Seiko Epson does not assume any liability for the occurrence of infringing any patent or copyright of third
party. This material does not authorize the licence for any patent or intellectual property rights.
• 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.
• The products (except for some product for automotive applications) listed up on this material are designed
to be used with ordinary electronic equipment (OA equipment, AV equipment, communications equipment,
measuring instruments etc). Seiko Epson does not assume any liability for the case using the products with
the appoication required high reliability or safety extremely (such as aerospace equipment etc).
When intending to use any our product with automotive application and the other application than
ordinary electronic equipments as above, please contact our sales representatives in advance.
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RX
-
4045
SA
/
NB
Contents
1. Overview........................................................................................................................1
2. Block Diagram ...............................................................................................................1
3. Description of Pins.........................................................................................................2
3.1. Pin Layout ........................................................................................................................................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 Electrical Characteristics............................................................................................................4
7.2. AC Electrical Characteristics ............................................................................................................5
8. Functional descriptions ..................................................................................................6
8.1. Overview of Functions ......................................................................................................................6
8.2. Description of Registers ...................................................................................................................7
8.3. Clock Precision Adjustment Function.............................................................................................14
8.4. Periodic Interrupt Function .............................................................................................................16
8.5. Alarm W function............................................................................................................................18
8.6. Alarm D function.............................................................................................................................20
8.7. /INT Output during Operation of Interrupt Function........................................................................21
8.8. The various detection Functions ....................................................................................................22
8.9. Read/Write of Data.........................................................................................................................25
8.10. External Connection Example ......................................................................................................30
9. External Dimensions / Marking Layout.........................................................................31
9.1. External Dimensions.......................................................................................................................31
9.2. Marking Layout ...............................................................................................................................31
10. Reference Data .........................................................................................................32
11. Application notes .......................................................................................................33
RX
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4045
SA
/
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Page - 1 MQ442-01
Miniature Serial Interface RTC Module
RX
-
4045
SA
/
NB
• Features built-in 32.768-kHz quartz oscillator, frequency adjusted for high precision
( ± 5 × 10
−6
when Ta = +25°C )
• Serial interface in 4 lines form
• Includes time (H/M/S) and calendar ( YR/MO/DATE/DAY ) counter functions ( BCD code )
• Select between 12-hr and 24-hr clock mode.
• Auto calculation of leap years until 2099
• Built-in high-precision clock precision control logic
• CPU interrupt generation function (cycle time range: 1 month to 0.5 seconds, includes
interrupt flags and interrupt stop function)
• Dual alarm functions ( Alarm_W: Day/Hour/Min, Alarm_D: Hour/Min )
• 32.768-kHz clock output
( Nch open drain output )
• Oscillation stop detection function ( used to determine presence of internal data )
• Power supply voltage monitoring function ( with selectable detection threshold )
• Wide clock ( retention ) voltage range: 1.15 V to 5.5 V
• Wide interface voltage range: 1.7 V to 5.5 V
• Low current consumption: 0.48 µA / 3.0 V ( Typ.)
1. Overview
This module is an four signal lines interface -compliant real-time clock which includes a 32.768-kHz quartz
oscillator that has been adjusted for high precision. In addition to providing a function for generating six types
of interrupts, a dual alarm function, an oscillation stop detection function (used to determine presence of valid
internal data at power-on), and a power supply voltage monitoring function, this module includes a digital clock
precision adjustment function that can be used to set various levels of precision.
Since the internal oscillation circuit is driven at a constant voltage, 32.768-kHz clock output is stable and free
of voltage fluctuation effects.
This implementation of multiple functions in one SMT package is ideal for applications ranging from cellular
phones to PDAs and other small electronic devices.
2. Block Diagram
32kHz
OUTPUT
CONTROL
OSC
COMPARATOR_D ALARM_D REGISTER
(MIN,HOUR)
ADDRESS
DECODER
ADDRESS
REGISTER
VOLTAGE
DETECT
DIV
TIME COUNTER
(SEC,MIN,HOUR,WEEK,DAY,MONTH,YEAR)
SHIFT REGISTER
I/O
CONTROL
FOUT
INTERRUPT CONTROL
CLK
DIVIDER
CORREC
-TION
VDD
GND
COMPARATOR_W ALARM_W REGISTER
(MIN,HOUR, WEEK)
CE
OSC
DETECT DI
/INT
DO
RX
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Page - 2 MQ442-01
3. Description of Pins
3.1. Pin Layout
RX - 4045 SA
1. N.C. 14. N.C.
2. CLK 13. DO
3. FOUT 12. DI
4. N.C. 11. GND
5. TEST 10. / INT
6. VDD 9. N.C.
7. CE
8. N.C.
SOP - 14pin
RX - 4045 NB
1. CE 22. N.C.
2. V
DD
21. N.C.
3.
(GND)
20. N.C.
4. TEST 19. N.C.
5. FOUT 18. N.C.
6. CLK 17. N.C.
7. DO 16. N.C.
8. DI 15. N.C.
9. GND 14. N.C.
10. / INT (13) −
11. N.C.
# 1
# 11
# 22
(#12)
(12) −
SON - 22pin
∗
∗
Note : See (GND) following
.
3.2. Pin Functions
Signal
name I / O Function
CE I
The CE pin is used for interfacing with the CPU. Should be held high to allow 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 V regardless of supply voltage.
CLK I
The CLK pin is used to input clock pulses synchronizing the input and output
of data to and from the DI and DO pins.Allows a maximum input voltage of
5.5 Vv regardless of supply voltage.
DI I
The DI pin is used to input data intended for writing in synchronization with the
CLK pin. CMOS input. Allows a maximum input voltage of 5.5 V regardless
of supply voltage.
DO O The DO pin is used to output data intended for reading in synchronization with
the CLK pin.CMOS output.
FOUT O
This is a 32.768-kHz clock output pin (N-ch open drain), for which output control is provided.
The output ON/OFF setting is controlled via the /CLEN1 and /CLEN2 bits; when either of
these bits = 0, a 32.768-kHz signal is output from the FOUT pin.
When output is stopped, high impedance is set.
/CLEN1
bit
/CLEN2
bit
FOUT
output
0 0 32.768 kHz
0 1 32.768 kHz
1 0 32.768 kHz
1 1
OFF ( Hi-z )
However it cannot be pulled up over VDD+0.3v.
/INT O
This interrupt output A pin is an N-ch open drain output.
This pin is able to output at low level when an interrupt occurs.
When output is OFF or when the power supply starts up from 0 V, high impedance is set.
Allows a maximum pull-up voltage of 5.5v regardless of supply voltage.
TEST − The factory testing uses this pin. Do not connect externally.
V
DD
− This pin is connected to a positive power supply.
GND − This pin is connected to a ground.
( GND ) − This pin has the same voltage level as GND. Do not connect externally.
N.C. −
This pin is not connected to the internal IC.
However, note with caution that the RX-4025NB's N.C. pins (pins 14 to 22) are interconnected
via the internal frame.
Leave N.C. pins open or connect them to GND or V
DD
.
Note: Be sure to connect a bypass capacitor rated at least 0.1 µF between V
DD
and GND.
RX
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4045
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Page - 3 MQ442-01
4. Absolute Maximum Ratings
GND = 0 V
Item Symbol Condition Rating Unit
Supply voltage V
DD
Between V
DD
and GND −0.3 to +6.5 V
Input voltage V
I
CE, CLK, DI pins GND−0.3 to +6.5 V
V
O1
FOUT, /INT pins GND−0.3 to +6.5 V
Output voltage
V
O2
DO pin GND−0.3 to V
DD
+0.3 V
Storage temperature T
STG
When stored separately, without
packaging −55 to +125 °C
5. Recommended Operating Conditions
GND = 0 V
Item Symbol Condition Min. Typ. Max. Unit
Operating supply voltage V
DD
− 1.7 3.0 5.5 V
Clock supply voltage V
CLK
− 1.15 3.0 5.5 V
Applied voltage when OFF V
PUP
/INT pin GND−0.3 5.5 °C
Operating temperature T
OPR
No condensation −40 +25 +85 °C
6. Frequency Characteristics
GND = 0 V
Item Symbol Condition Rating Unit
Frequency precision ∆ f / f Ta = +25 °C
V
DD
= 3.0 V
AA ; 5 ± 5
(∗1)
AC ; 0 ± 5
(∗1)
× 10
−6
Frequency/voltage
characteristics f / V Ta = +25 °C
V
DD
= 2 V to 5 V ± 1 Max. × 10
−6
/ V
Frequency/temperature
characteristics Top Ta = −20 °C to +70 °C,
V
DD
= 3.0 V; +25 °C reference +10 / −120 × 10
−6
Oscillation start time t
STA
Ta = +25 °C
V
DD
= 2.0 V 1 Max. s
Aging fa Ta = +25 °C
V
DD
=3.0 V; first year ± 5 Max. × 10
−6
/ year
∗1)
AC rank. Precision gap per month: 13 seconds (excluding offset value)
RX
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4045
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Page - 4 MQ442-01
7. Electrical Characteristics
7.1. DC Electrical Characteristics
7.1.1. DC electrical characteristics (1) * Unless otherwise specified, GND
= 0 V, V
DD
= 3 V, Ta = −40 °C to +85 °C
Item Symbol Condition Min. Typ. Max. Unit
V
DD
=5 V 0.60 1.80
Current (1) I
DD1
FOUT, / INT = OFF.
CE, CLK, DI, DO = GND V
DD
=3 V 0.48 1.20
µA
Current (2) I
DD2
FOUT = ON
CE, CLK, DI, DO = GND V
DD
=3 V 0.65 2.00 µA
High-level input voltage V
IH
0.8 × V
DD
5.5 V
Low-level input voltage V
IL
CE, CLK, DI pins
V
DD
= 1.7 to 5.5 V GND − 0.3 0.2 × V
DD
V
High-level input current I
OH
DO pin, V
OH
= V
DD
− 0.5 V −0.5 mA
I
OL1
/INT pin, V
OL
= 0.4 V 2.0 mA
Low-level input current
I
OL2
DO, FOUT pins, V
OL
= 0.4 V 0.5 mA
Input leakage current I
IL
CLK pin
V
I
= 5.5 V or GND, V
DD
= 5.5 V −1 1 µA
7.1.2. DC electrical characteristics (2) * Unless otherwise specified, GND
= 0 V, V
DD
= 3 V, Ta = −40 °C to +85 °C
Item Symbol Condition Min. Typ. Max. Unit
Pull-down resistor R
DNCE
CE pin 40 120 400 kΩ
DO pin
V
O
= 5.5 V or GND, V
DD
= 5.5 V −1 1 µA
Output current when OFF I
OZ1
FOUT, /INT pins
V
O
= 5.5 V −1 1 µA
High-voltage
mode V
DETH
V
DD
pin, Ta = −30 to +70 °C 1.90 2.10 2.30 V
Power
supply
detection
voltage
Low-voltage
mode V
DETL
V
DD
pin, Ta = −30 to +70 °C 1.15 1.30 1.45 V
RX
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Page - 5 MQ442-01
7.2. AC Electrical Characteristics
∗ Unless otherwise specified: GND = 0 V, V
DD
= 1.7 V to 5.5 V, Ta = −40 °C to +85 °C
∗ Input conditions: V
IH
= 0.8 × V
DD
, V
IL
= 0.2 × V
DD
, V
OH
= 0.8 × V
DD
, V
OL
= 0.2 ×V
DD
, CL = 50 pF
Item Symbol Condition Min. Typ. Max. Unit
CE setup time t
CES
400 ns
CE hold time t
CEH
400 ns
CE recovery time t
CR
62 µs
CLK clock frequency f
CLK
1.0 MHz
CLK " H " pulse width t
CKH
400 ns
CLK " L " pulse width t
CKL
400 ns
CLK setup time t
CKS
200 ns
Data output delay time t
RD
300 ns
Data output floating time t
RZ
300 ns
Data output floating time after falling if CE t
CEZ
300 ns
Input data setup time t
DS
200 ns
Input data hold time t
DH
200 ns
CLK
t
CES
DO
DI
CE
t
RD
t
CKL
t
CEZ
t
DS
t
DH
t
RD
t
CEH
t
CKH
t
CKS
t
CR
t
RZ
RX
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4045
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Page - 6 MQ442-01
8. Functional descriptions
8.1. Overview of Functions
1) Clock functions
This function is used to set and read out month, date, day, hour, minute, and second.
Any (two-digit) year that is a multiple of 4 is treated as a leap year and calculated automatically as such until the year
2099.
∗ For details, see "8.2. Description of Registers".
2) Clock precision adjustment function
The clock precision can be adjusted forward or back in units of ± 3.05 × 10
−6
. This function can be used to implement
a higher-precision clock function, such as by:
• enabling higher clock precision throughout the year by taking seasonal clock precision adjustments into account in
advance, or
• enabling correction of temperature-related clock precision variation in systems that include a temperature detection
function.
Note: Only the clock precision can be adjusted. The adjustments have no effect on the 32.768-kHz output from the
FOUT pin.
∗ For details, see "8.3. Clock Precision Adjustment Function".
3) Periodic interrupt function
In addition to the alarm function, Periodic interrupts can be output via the /INT pin.
Select among five Periodic frequency settings: 2 Hz, 1 Hz, 1/60 Hz, hourly, or monthly.
Select among two output waveforms for periodic interrupts: an ordinary pulse waveform (2 Hz or 1 Hz) or a waveform
(every second, minute, hour, or month) for CPU-level interrupts that can support CPU interrupts.
A polling function is also provided to enable monitoring of pin states via registers.
∗ For details, see "8.4. Periodic Interrupt Function".
4) Alarm functions
This module is equipped with two alarm functions (Alarm W and Alarm D) that output interrupt signals to the host at
preset times. The Alarm W function can be used for day, hour, and minute-based alarm settings, and it outputs
interrupt signals via the /INT pin. Multiple day settings can be selected (such as Monday, Wednesday, Friday,
Saturday, and Sunday). The Alarm D function can be used only for hour or minute-based settings, and it outputs
interrupt signals via the /INT pin.
A polling function is also provided to enable checking of each alarm mode by the host.
∗ For details on the Alarm W function, see "8.5. Alarm W function" and for the Alarm D function, see "8.6. Alarm D Function".
5) Oscillation stop detection function, power drop detection function (voltage monitoring function), and
power-on reset detection function
The oscillation stop detection function uses registers to record when oscillation has stopped.
The power drop detection function (supply voltage monitoring function) uses registers to record when the supply
voltage drops below a specified voltage threshold value. Use registers to specify either of two voltage threshold
values: 2.1 V or 1.3 V. Voltage sampling is performed once per second in consideration of the module's low current
consumption.
While the oscillation stop detection function is useful for determining when clock data has become invalid, the supply
voltage monitoring function is useful for determining whether or not the clock data is able to become invalid. The
supply voltage monitoring function can also be used to monitor a battery's supply voltage.
When these functions are utilized in combination with the power-on reset detection function, they are useful for
determining whether clock data is valid or invalid when checking for power-on from 0 V or for back-up.
∗ For details, see "8.7. Detection Functions".
6) Interface with CPU
The RX-4045 is connected to the CPU by four signal lines CE (Chip Enable), CLK (Clock), DI (Data Input),
and DO (Data Output),through which it reads and writes data from and to the CPU.
The CPU can be accessed when the CE pin is held high.Access clock pulses have a maximum frequency of 1 MHz
allowing high-speed data transfer to the CPU.
∗ For further description of data read/write operations, see "8.9. Read/Write of data ".
7) 32.768-kHz clock output
The 32.768-kHz clock (with precision equal to that of the built-in quartz oscillator) can be output via the FOUT pin.
Note: The precision of this 32.768-kHz clock output via the FOUT pin cannot be adjusted (even when using the clock
precision adjustment function).
RX
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Page - 7 MQ442-01
8.2. Description of Registers
8.2.1. Register table
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
note
0 Seconds
!
S40 S20 S10 S8 S4 S2 S1
∗5
1 Minutes
!
M40 M20 M10 M8 M4 M2 M1
∗5
2 Hours
!
!
H20
P , /A H10 H8 H4 H2 H1
∗5
3 Weekdays
! !
!
!
!
W4 W2 W1
∗5
4 Days
! !
D20 D10 D8 D4 D2 D1
∗5
5 Months 0
!
!
MO10 MO8 MO4 MO2 MO1
∗4, ∗5
6 Years Y80 Y40
Y20 Y10 Y8 Y4 Y2 Y1
−
7 Digital Offset 0
F6 F5 F4 F3 F2 F1 F0
∗4
8 Alarm_W ; Minute
!
WM40 WM20 WM10 WM8 WM4 WM2 WM1
∗5
9 Alarm_W ; Hour
!
!
WH20
WP,/A WH10 WH8 WH4 WH2 WH1
∗5
A Alarm_W ; Weekday
!
WW6 WW5 WW4 WW3 WW2 WW1 WW0
∗5
B Alarm_D ; Minute
!
DM40 DM20 DM10 DM8 DM4 DM2 DM1
∗5
C Alarm_D ; Hour
!
!
DH20
DP , /A DH10 DH8 DH4 DH2 DH1
∗5
D Reserved Reserved ∗3
E Control 1
WALE DALE /12 , 24 /CLEN2 TEST CT2 CT1 CT0
∗1, ∗2, ∗6
F Control 2
VDSL VDET /XST PON /CLEN1 CTFG WAFG DAFG
∗1, ∗6
Caution points:
∗1. The PON bit is a power-on reset flag bit.
The PON bit is set to "1" when a reset occurs, such as during the initial power-up or when recovering from a
supply voltage drop. At the same time, all bits in the Control 1 and Control 2 registers except for the PON and /
XST bits are reset to "0".
Note: At this point, all other register values are undefined, so be sure to perform a reset before using the module.
Also, be sure to avoid entering incorrect date and time data, as clock operations are not guaranteed when
the time data is incorrect.
∗2. The TEST bit is used by the manufacturer for testing. Be sure to set "0" for this bit.
∗3. Address D (a reserved register) is used for the manufacturer's settings. Do not read from or write to this register.
∗4. All bits marked with a " 0
" in the above table should be set as "0". Their value when read will be "0".
∗5. All bits marked with "
!
" are read-only bits. Their value when read is always "0".
∗6. When PON bit became 1 because power-on reset function worked, /CLEN1 and /CLEN2 bit become 0.
When /CLEN1 and /CLEN2 bit become 1, FOUT output stops.
/CLEN1
bit
/CLEN2
bit
FOUT
output
Χ Χ OFF ( " L " )
0 0 32.768 kHz
0 1 32.768 kHz
1 0 32.768 kHz
1 1 OFF ( " Hi-z " )
' Χ ' Don't care.
RX
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Page - 8 MQ442-01
8.2.2. Time counter (Reg 0 to 2)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
0
Seconds
!
S40 S20 S10 S8 S4 S2 S1
1
Minutes
!
M40 M20 M10 M8 M4 M2 M1
2
Hours
! !
H20
P, /A H10 H8 H4 H2 H1
• The time counter counts seconds, minutes, and hours.
• The data format is BCD format
(except during 12-hour mode)
.
For example, when the "seconds" register value is
"0101 1001" it indicates 59 seconds.
∗ Note with caution that writing non-existent time data may interfere with normal operation of the time counter.
1) Second counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
0
Seconds
!
S40 S20 S10 S8 S4 S2 S1
• This second counter counts from "00" to "01," "02," and up to 59 seconds, after which it starts again from
00 seconds.
• When a value is written to the second counter, the internal counter is also reset to zero in less than one
second.
2) Minute counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
1 Minutes
!
M40 M20 M10 M8 M4 M2 M1
• This minute counter counts from "00" to "01," "02," and up to 59 minutes, after which it starts again from 00
minutes.
3) Hour counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
2 Hours
! !
H20
P , /A H10 H8 H4 H2 H1
• The hour counter counts hours, and its clock mode differs according to the value of its /12,24 bit.
• During 24-hour clock operation, bit 5 functions as H20 (two-digit hour display). During 12-hour clock
operation, bit 5 functions as an AM/PM indicator ("0" indicates AM and "1" indicates PM).
/12,24 bit Description Address 2 (Hours register) data [h] during 24-hour and
12-hour clock operation modes
0 12-hour
clock
1 24-hour
clock
24-hour clock 12-hour clock 24-hour clock 12-hour clock
00 12 ( AM 12 ) 12 32 ( PM 12 )
01 01 ( AM 01 ) 13 21 ( PM 01 )
02 02 ( AM 02 ) 14 22 ( PM 02 )
03 03 ( AM 03 ) 15 23 ( PM 03 )
04 04 ( AM 04 ) 16 24 ( PM 04 )
05 05 ( AM 05 ) 17 25 ( PM 05 )
06 06 ( AM 06 ) 18 26 ( PM 06 )
07 07 ( AM 07 ) 19 27 ( PM 07 )
08 08 ( AM 08 ) 20 28 ( PM 08 )
09 09 ( AM 09 ) 21 29 ( PM 09 )
10 10 ( AM 10 ) 22 30 ( PM 10 )
11 11 ( AM 11 ) 23 31 ( PM 11 )
RX
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Page - 9 MQ442-01
8.2.3. Day counter (Reg 3)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
3
Days
! ! ! ! !
W4 W2 W1
• The day counter is a divide-by-7 counter that counts from 00 to 01 and up 06 before starting again from 01.
• The correspondence between days and count values is shown below.
Days W4 W2 W1 Day Remark
0 0 0 Sunday 00 h
0 0 1 Monday 01 h
0 1 0 Tuesday 02 h
0 1 1 Wednesday 03 h
1 0 0 Thursday 04 h
1 0 1 Friday 05 h
Write / Read
1 1 0 Saturday 06 h
Write prohibit 1 1 1 − Do not enter a setting for this bit.
8.2.4. Calendar counter (Reg 4 to 6)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
4
Days
! !
D20 D10 D8 D4 D2 D1
5
Months 0
! !
MO10 MO8 MO4 MO2 MO1
6
Years Y80 Y40 Y20 Y10 Y8 Y4 Y2 Y1
• The auto calendar function updates all dates, months, and years from January 1, 2001 to December 31, 2099.
• The data format is BCD format. For example, a date register value of "0011 0001" indicates the 31st.
∗ Note with caution that writing non-existent date data may interfere with normal operation of the calendar counter.
1) Date counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
4 Days
! !
D20 D10 D8 D4 D2 D1
• The updating of dates by the date counter varies according to the month setting.
∗ A leap year is set whenever the year value is a multiple of four (such as 04, 08, 12, 88, 92, or 96).
Days Month Date update pattern
1, 3, 5, 7, 8, 10, or 12 01, 02, 03 to 30, 31, 01…
4, 6, 9, or 11 01, 02, 03 to 30, 01, 02…
February in leap year 01, 02, 03 to 28, 29, 01…
Write / Read
February in normal year 01, 02, 03 to 28, 01, 02…
2) Month counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
5 Months 0
! !
MO10 MO8 MO4 MO2 MO1
• The month counter counts from 01 (January), 02 (February), and up to 12 (December), then starts again at
01 (January).
∗ Be sure to set a "0" for any bit whose value is shown above as "0". A zero is returned when any of these
bits is read.
3) Year counter
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
6 Years Y80 Y40 Y20 Y10 Y8 Y4 Y2 Y1
• The year counter counts from 00, 01, 02 and up to 99, then starts again at 00.
∗ In any year that is a multiple of four (04, 08, 12, 88, 92, 96, etc.), the dates in February are counted from
01, 02, 03 and up to 29 before starting again at 01.
RX
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Page - 10 MQ442-01
8.2.5. Clock precision adjustment register (Reg 7)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
7 Digital Offset 0 F6 F5 F4 F3 F2 F1 F0
(Default) (0) (0) (0) (0) (0) (0) (0) (0)
• The binary encoded settings in the seven bits from F6 to F0 are used to set the precision of the clock generated
from the 32768-Hz internal oscillator up to ±189 × 10
−6
in the forward (ahead) or reverse (behind) direction, in
units of ± 3.05 × 10
−6
. (Only the clock precision can be adjusted. The 32.768-kHz output from the FOUT pin is
not affected.)
• When not using this function, be sure to set "0" for bits F6 to F0.
∗ For details, see "8.3. Clock Precision Adjustment Function".
8.2.6. Alarm_W register (Reg 8 to A)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
8
Alarm_W ; Minute
!
WM40 WM20 WM10 WM8 WM4 WM2 WM1
9
Alarm_W ; Hour
! !
WH20
WP , /A WH10 WH8 WH4 WH2 WH1
A
Alarm_W ; Day
!
WW6 WW5 WW4 WW3 WW2 WW1 WW0
• The Alarm W function is used, along with the WALE and WAFG bits, to set alarms for specified day, hour, and
minute values.
• When the Alarm_W setting matches the current time, /INT pin is set to "L" and the WALE bit is set to "1".
Note: If the current date/time is used as the Alarm_W setting, the alarm will not occur until the counter counts up
to the current date/time (i.e., an alarm will occur next time, not immediately).
• During 24-hour clock operation, the "Alarm_W ; Hours" register's bit 5 (WH20, WP, /A) functions as WH20
(two-digit hour display), and during 12-hour clock operation it functions as an AM/PM indicator.
• When the Alarm_W function's day values (WW6 to WW0) are all "0" Alarm W does not occur.
∗ For details, see "8.5. Alarm W Function".
8.2.7. Alarm_ D register (Reg B and C)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
B
Alarm_D ; Minute
!
DM40 DM20 DM10 DM8 DM4 DM2 DM1
C
Alarm_D ; Hour
! !
DH20
DP , /A DH10 DH8 DH4 DH2 DH1
• The Alarm D function is used, along with the DALE and DAFG bits, to set alarms for specified hour and minute
values.
• When the Alarm_D setting matches the current time, /INT pin is set to "L" and the DALE bit is set to "1".
Note: If the current time is used as the Alarm_D setting, the alarm will not occur until the counter counts up to the
current time (i.e., an alarm will occur next time, not immediately).
• During 24-hour clock operation, the "Alarm_D ; Hours" register's bit 5 (DH20, DP, /A) functions as DH20 (two-digit
hour display), and during 12-hour clock operation it functions as an AM/PM indicator.
∗ For details, see "8.6. Alarm D Function".
RX
-
4045
SA
/
NB
Page - 11 MQ442-01
8.2.8. Control register 1 (Reg E)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
E Control 1 WALE DALE /12 , 24
/CLEN2
TEST CT2 CT1 CT0
(Default) (0) (0) (0) (0) (0) (0) (0) (0)
∗) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
1) WALE bit
This bit is used to set up the Alarm W function (to generate alarms matching day, hour, or minute settings).
WALE Data Description
0 Alarm_W, match comparison operation invalid
∗ Default
Write / Read 1 Alarm_W, match comparison operation valid (/INT = "L" when
match occurs)
∗ For details, see "8.5. Alarm W Function".
2) DALE bit
This bit is used to set up the Alarm D function (to generate alarms matching hour or minute settings).
DALE Data Description
0 Alarm_D, match comparison operation invalid
∗ Default
Write / Read 1 Alarm_D, match comparison operation valid (/INT = "L" when
match occurs)
∗ For details, see "8.6. Alarm D Function".
3) /12,24 bit
This bit is used to select between 12-hour clock operation and 24-hour clock operation.
/12,24 Data Description
0 12-hour clock
∗ Default
Write / Read 1 24-hour clock
∗ Be sure to select between 12-hour and 24-hour clock operation before writing the time data.
∗ See also "3) Hour counter" in section 8.2.4.
4) /CLEN2 bit
It combines /CLEN1 bit, and is bit controlling FOUT output.
When /CLEN1 and /CLEN2 bit become 1, FOUT output stops.
When PON bit became 1 because power-on reset function worked, /CLEN1 and /CLEN2 bit become 0.
5) TEST bit
This bit is used by the manufacturer for testing. Be sure to write "0" to this bit.
Be careful to avoid writing a "1" to this bit when writing to other bits.
TEST Data Description
0 Normal operation mode
∗ Default
Write / Read 1 Setting prohibited (manufacturer's test mode)
6) CT2, CT1, and CT0 bits
These bits are used to set up the operation of the periodic interrupt function that uses the /INT pin.
/INT pin's output setting
CT2 CT1 CT0 Waveform mode Cycle/Fall timing
0 0 0 − /INT = Hi-Z (= OFF)
∗ Default
0 0 1 − /INT = Fixed low
0 1 0 Pulse mode
∗1)
2 Hz (50% duty)
0 1 1 Pulse mode
∗1)
1 Hz (50% duty)
1 0 0 Level mode
∗2)
Once per second (Synchronous with per-second
count-up)
1 0 1 Level mode
∗2)
Once per minute (Occurs when seconds reach ":00")
1 1 0 Level mode
∗2)
Once per hour (Occurs when minutes and seconds
reach "00:00")
1 1 1 Level mode
∗2)
Once per month (Occurs at 00:00:00 on first day of
month)
∗ For details, see "8.4. Periodic Interrupt".
RX
-
4045
SA
/
NB
Page - 12 MQ442-01
8.2.9. Control register 2 (Reg F)
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
F Control 2 VDSL VDET / XST PON /CLEN1 CTFG WAFG DAFG
(Default) (0) (0) (−) (1) (0) (0) (0) (0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
∗2) '"−" indicates undefined status.
1) VDSL bit
This bit is used to set the power drop detection function's threshold voltage value.
VDSL Data Description
0 Sets 2.1 V as the power drop detection function's threshold
voltage value
∗ Default
Write / Read
1 Sets 1.3 V as the power drop detection function's threshold
voltage value
∗ For details, see "8.7. Detection Functions".
2) VDET bit
This bit indicates the power drop detection function's detection results.
VDET = "1" once a power voltage drop has occurred.
VDET Data Description
0
Clears the VDET bit to zero, restarts the power drop detection
operation and sets up for next power drop detection operation
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Power drop was not detected
∗ Default
Read
1
Power drop was detected
(result is that bit value is held until cleared to zero)
∗ For details, see "8.7. Detection Functions".
3) / XST bit
This bit indicates the oscillation stop detection function's detection results.
If a "1" has already been written to this bit, it is cleared to zero when stopping of internal oscillation is detected.
/ XST Data Description
0
Setting prohibited (do not set this bit value, even though it has no
effect)
Write
1
Sets the oscillation stop detection function as use-enabled and
sets up for next detection operation
0
Oscillation stop was detected
(result is that bit value is held until a "1" is written)
Read
1
Oscillation stop was not detected
∗ For details, see "8.7. Detection Functions".
4) PON bit
This bit indicates the power-on reset detection function's detection results.
The PON bit is set (= 1) when the internal power-on reset function operates.
PON Data Description
0
Clears the PON bit to zero and sets up next detection operation
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Power-on reset was not detected
Read
1
Power-on reset was detected
(result is that bit value is held until cleared to zero)
∗ Default
∗ When PON = "1" all bits in the Clock Precision Adjustment register and in the Control 1 and Control 2
registers (except for the PON and / XST bits) are reset to "0". This also causes output from /INT and
/INT pin to be stopped (= Hi-Z).
∗ For details, see "8.7. Detection Functions".
RX
-
4045
SA
/
NB
Page - 13 MQ442-01
5) /CLEN1 bit
This bit is controlling FOUT output with /CLEN2 bit.
When /CLEN1 and /CLEN2 bit set to 1, FOUT output stops.
When PON bit became 1 because power-on reset function worked, /CLEN1 and /CLEN2 bit become 0.
6) CTFG bit
During a read operation, this bit indicates the /INT pin's priodic interrupt output status.
This status can be set as OFF by writing a "0" to this bit when /INT = " L".
CTFG Data Description
0
A "0" can be written only when the periodic interrupt is in level
mode, at which time the /INT pin is set to OFF (Hi-z) status. (Only
when Alarm_D does not match)
∗ After a "0" is written, the value still becomes "1" again at the
next cycle.
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Periodic interrupt output OFF status; /INT = OFF (Hi-z)
∗ Default
Read
1
Periodic interrupt output ON status; /INT = "L"
∗ For details, see "8.4. Periodic Interrupt Function".
7) WAFG bit
This bit is valid only when the WALE bit value is "1". The WAFG bit value becomes "1" when Alarm W has
occurred.
The /INT = "L" status that is set at this time can be set to OFF by writing a "0" to this bit.
WAFG Data Description
0
/INT pin = OFF (Hi-z)
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Alarm_W time setting does not match current time
(This bit's value is always "0" when the WALE bit's setting is "0")
∗ Default
Read
1
Alarm_W setting matches current time
(Result is that bit value is held until cleared to zero)
∗ For details, see "8.5. Alarm W Function".
8) DAFG bit
This bit is valid only when the DALE bit value is "1". The DAFG bit value becomes "1" when Alarm D has
occurred.
The /INT = "L" status that is set at this time can be set to OFF by writing a "0" to this bit.
DAFG Data Description
0
/INT pin = OFF (Hi-z) (but only when the periodic interrupt output
status is OFF)
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Alarm_D time setting does not match current time
(This bit's value is always "0" when the DALE bit's setting is "0")
∗ Default
Read
1
Alarm_D time setting matches current time
(result is that bit value is held until cleared to zero)
∗ For details, see "8.6. Alarm D function".
RX
-
4045
SA
/
NB
Page - 14 MQ442-01
8.3. Clock Precision Adjustment Function
The clock precision can be set ahead or behind.
This function can be used to implement a higher-precision clock function, such as by:
• enabling higher clock precision throughout the year by taking seasonal clock precision adjustments into
account in advance, or
• enabling correction of temperature-related clock precision variation in systems that include a temperature
detection function.
∗ Note: Only the clock precision can be adjusted. The adjustments have no effect on the 32.768-kHz output from
the FOUT pin.
8.3.1. Related register
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
7 Digital Offset 0 F6 F5 F4 F3 F2 F1 F0
(Default) (0) (0) (0) (0) (0) (0) (0) (0)
∗) Be sure to set a "0" for any bit whose value is shown above as "0". A zero is returned when any of these bits is read.
• The binary encoded settings in the seven bits from F6 to F0 are used to set the precision of the clock generated
from the 32768-Hz internal oscillator up to ±189.1 × 10
−6
in the forward (ahead) or reverse (behind) direction, in
units of ± 3.05 × 10
−6
.
∗1) When not using this function, be sure to set "0" for bits F6 to F0.
∗2) This function operates every twenty seconds (at 00 seconds, 20 seconds, and 40 seconds within each
minute), which changes the cycle of the periodic interrupts that occur via this timing.
(See "8.4. Periodic Interrupt
Function".)
8.3.2. Adjustment capacity
1) Adjustment range and resolution
Adjustment range
Adjustment resolution
Internal timing of adjustment
−189.1 x 10
−6
to +189.1 x 10
−6
± 3.05 x 10
−6
Once every 20 seconds
(at "00", "20" and "40" seconds)
2) Adjustment amount and adjustment value
Adjustment amount
Adjustment data bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
(× 10
−6
)
Decimal / Hexadecimal
0 F6 F5 F4 F3 F2 F1 F0
−189.10 +63 / 3F h 0 0 1 1 1 1 1 1
−186.05 +62 / 3E h 0 0 1 1 1 1 1 0
−183.00 +61 / 3D h 0 0 1 1 1 1 0 1
•
•
•
•
•
•
•
•
•
−9.15 +4 / 04 0 0 0 0 0 1 0 0
−6.10 +3 / 03 0 0 0 0 0 0 1 1
−3.05 +2 / 02 h 0 0 0 0 0 0 1 0
OFF 1 / 01 h 0 0 0 0 0 0 0 1
OFF 0 / 00 h 0 0 0 0 0 0 0 0
+3.05 −1 / 7F h 0 1 1 1 1 1 1 1
+6.10 −2 / 7E h 0 1 1 1 1 1 1 0
+9.15 −3 / 7D h 0 1 1 1 1 1 0 1
•
•
•
•
•
•
•
•
•
+183.00 −60 / 44 h 0 1 0 0 0 1 0 0
+186.05 −61 / 43 h 0 1 0 0 0 0 1 1
+189.10 −62 / 42 h 0 1 0 0 0 0 1 0
OFF −63 / 41 h 0 1 0 0 0 0 0 1
OFF −64 / 40 h 0 1 0 0 0 0 0 0
RX
-
4045
SA
/
NB
Page - 15 MQ442-01
8.3.3. Adjustment examples
Example 1) Setting time forward
Objective) To adjust (advance) the clock precision when FOUT clock output is 32767.7 Hz
(1) Determine the current amount of variance
32767.7 Hz → (32767.7 − 32768) / 32768
∗ [ 32768 ] = Reference values
→ −9.16 × 10
−6
(2) Calculate the optimum adjustment data (decimal value) relative to the current variance.
Adjustment data = variance / adjustment resolution
= −9.16 / 3.05
≈ −3
(decimal values are rounded down from 4 and up from 5)
∗ For adjusting forward from a retarded variance, this formula can be corrected using reciprocal numbers, but since this
product inverts the +/- attributes, this formula can be used as it is.
(3) Calculate the setting adjustment data (hexadecimal)
To calculate the setting adjustment data while taking 7-bit binary encoding into account,
subtract the adjustment data (decimal) from 128 (80h).
Setting adjustment data = 128 − 3 = 125 (decimal)
= 80h − 03h = 7Dh (hexadecimal)
Example 2) Setting time backward
Objective) To adjust (set back) the clock precision when FOUT clock output is 32768.3 Hz
(1) Determine the current amount of variance
32768.3 Hz → (32768.3 − 32768) / 32768
∗ [ 32768 ] = reference values
→ +9.16 × 10
−6
(2) Calculate the optimum adjustment data (decimal value) relative to the current variance.
Adjustment data = (variance / adjustment resolution) + 1
= (+9.16 / 3.05) + 1
∗ Add 1 since reference value is 01h
≈ +4
(decimal values are rounded down from 4 and up from 5)
∗ For adjusting backward from an advanced variance, this formula can be corrected using reciprocal numbers, but
since this product inverts the +/- attributes, this formula can be used as it is.
(3) Calculate the setting adjustment data (hexadecimal)
The value "4" can be used in hexadecimal as it is (04h).
Setting adjustment data = 04 h (hexadecimal)
RX
-
4045
SA
/
NB
Page - 16 MQ442-01
8.4. Periodic Interrupt Function
Periodic interrupt output can be obtained via the /INT pin.
Select among five periodic-cycle settings: 2 Hz (once per 0.5 seconds), 1 Hz (once per second), 1/60 Hz (once
per minute), 1/3600 Hz (once per hour), or monthly (on the 1
st
of each month).
Select among two output waveforms for periodic interrupts: an ordinary pulse waveform (2 Hz or 1 Hz) or a
waveform (every second, minute, hour, or month) for CPU-level interrupts that can support CPU interrupts.
A polling function is also provided to enable monitoring of pin states via registers.
8.4.1. Related registers
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
E Control 1
WALE DALE /12 , 24 /CLEN2 TEST
CT2 CT1 CT0
(Default)
(0) (0) (0) (0) (0)
(0) (0) (0)
F Control 2
VDSL VDET / XST PON /CLEN1
CTFG
WAFG DAFG
(Default)
(0) (0) (−) (1) (0)
(0)
(0) (0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
∗2) "−" indicates undefined status.
1) CTFG bit
During a read operation, this bit indicates the /INT pin's periodic interrupt output status.
This status can be set as OFF by writing a "0" to this bit when /INT = " L". .
CTFG Data Description
0
A "0" can be written only when the periodic interrupt is in level
mode, at which time the /INT pin is set to OFF (Hi-z) status. (Only
when Alarm_D does not match)
∗ After a "0" is written, the value still becomes "1" again at the
next cycle.
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
periodic interrupt output OFF status; /INT = OFF (Hi-z)
∗ Default
Read
1
Periodic interrupt output ON status; /INT = "L"
2) CT2, CT1, CT0 bit
Combinations of these three bits are used to change the /INT pin's output status.
/INT pin's output setting
CT2 CT1 CT0 Waveform mode Cycle / Fall timing
0 0 0 − /INT = Hi-z (= OFF)
∗ Default
0 0 1 − /INT = Fixed low
0 1 0 Pulse mode
∗1)
2 Hz (50% duty)
0 1 1 Pulse mode
∗1)
1 Hz (50% duty)
1 0 0 Level mode
∗2)
Once per
second
(Synchronous with per-second
count-up)
1 0 1 Level mode
∗2)
Once per
minute (Occurs when seconds reach ":00")
1 1 0 Level mode
∗2)
Once per hour (Occurs when minutes and seconds
reach "00:00")
1 1 1 Level mode
∗2)
Once per
month
(Occurs at 00:00:00 on first day of
month)
∗ The /INT pin goes low ("L") when the Alarm_D function operates, but you can prevent that effect by setting
"0" for CT2, CT1, and CT0 to stop this function.
∗ See the next page's description of pulse mode/level mode waveforms.
RX
-
4045
SA
/
NB
Page - 17 MQ442-01
8.4.2. Mode-specific output waveforms
∗1) Pulse mode
A 2-Hz or 1-Hz clock pulse is output.
The relation between the clock pulse and the count operation is shown below.
/INT pin
Overwrite seconds counter
CTFG bit
92µs (approx)
(Count up seconds)
Note 1: As is shown in the above diagram, the seconds register's count up operation occurs approximately
92 µs after the falling edge of the /INT output. Therefore, if the clock's value is read immediately
after the output's falling edge, the read clock value may appear to be about one second slower than
the RTC module's clock value.
Note 2: When the seconds counter is overwritten, the counter for time values under one second is also
reset, which causes the /INT level to go low ("L") again.
Note 3: When using the clock precision adjustment function, the periodic interrupt's cycle changes once
every 20 seconds.
During pulse mode:
The period during which the output pulse is low can be adjusted backward or forward up to
±3.784 msec.
(For example, the duty for the 1-Hz setting can be adjusted ±0.3784% from 50%.)
∗2) Level mode
Select among four interrupt cycles: one second, one minute, one hour, or one month.
Counting up of seconds occurs in sync with the falling edge of the interrupt output. The following is a timing
chart when a one-second interrupt cycle has been set.
/INT pin
(Count up seconds)
Write 0 to CTFG
CTFG bit
(Count up seconds)
(Count up seconds)
Write 0 to CTFG
Note: When using the clock precision adjustment function, the periodic interrupt's cycle changes once every
20 seconds.
During level mode
A one-second period can be adjusted backward or forward up to ±3.784 msec.
RX
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4045
SA
/
NB
Page - 18 MQ442-01
8.5. Alarm W function
The Alarm W function generates interrupt signals (output via the /INT pin) that correspond to specified days, hours,
and minutes.
For description of the Alarm D function, which supports only hour and minute data, see "8.6. Alarm D Function".
Multiple day settings can be selected (such as Monday, Wednesday, Friday, Saturday, and Sunday).
A polling function is also provided to enable checking of each alarm mode by the host.
8.5.1. Related registers
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
1
Minutes
!
M40 M20 M10 M8 M4 M2 M1
2
Hours
! !
H20
P, /A H10 H8 H4 H2 H1
3
Days
! ! ! ! !
W4 W2 W1
8
Alarm_W ; Minute
!
WM40 WM20 WM10 WM8 WM4 WM2 WM1
9
Alarm_W ; Hour
! !
WH20
WP, /A WH10 WH8 WH4 WH2 WH1
A
Alarm_W ; Day
!
WW6 WW5 WW4 WW3 WW2 WW1 WW0
Control 1 WALE
DALE
/12, 24
/CLEN2 TEST CT2 CT1 CT0
E
(Default)
(0)
(0)
(0)
( 0 ) ( 0 ) (0) (0) (0)
Control 2
VDSL VDET / XST PON /CLEN1 CTFG
WAFG
DAFG
F
(Default) (0) (0) (−) ( 1 ) ( 0 ) (0)
(0)
(0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
∗2) "
○
" indicates write-protected bits. A zero is always read from these bits.
∗3) "−" indicates undefined status.
• When the Alarm_W setting matches the current time, /INT pin is set to "L" and the WALE bit is set to "1".
Note: If the current date/time is used as the Alarm_W setting, the alarm will not occur until the counter counts up
to the current date/time (i.e., an alarm will occur next time, not immediately).
• During 24-hour clock operation, the "Alarm_W ; Hours" register's bit 5 (WH20, WP, /A) functions as WH20
(two-digit hour display), and during 12-hour clock operation it functions as an AM/PM indicator.
• When the Alarm_W function's day values (WW6 to WW0) are all "0" Alarm W does not occur.
1) WALE bit
This bit is used to set up the Alarm W function (to generate alarms matching day, hour, or minute settings).
WALE Data Description
0 Alarm_W, match comparison operation invalid
∗ Default
Write / Read 1 Alarm_W, match comparison operation valid (/INT = "L" when
match occurs)
∗ When using the Alarm W function, first set this WALE bit value as "0," then stop the function. Next, set
the day, hour, minute, and the WAFG bit. Finally, set "1" to the WALE bit to set the Alarm W function as
valid. The reason for first setting the WALE bit value as "0" is to prevent /INT = "L" output in the event that
a match between the current time and alarm setting occurs while the alarm setting is still being made.
2) WAFG bit
This bit is valid only when the WALE bit value is "1". When a match occurs between the Alarm_W setting and
the current time, the WAFG bit value becomes "1" approximately 61 µs afterward. (There is no effect when the
WALE bit becomes "0".)
The /INT = "L" status that is set at this time can be set to OFF by writing a "0" to this bit.
WAFG Data Description
0
/INT pin = OFF (Hi-z)
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Alarm_W time setting does not match current time
(This bit's value is always "0" when the WALE bit's setting is "0")
∗ Default
Read
1
Alarm_W setting matches current time
(Result is that bit value is held until cleared to zero)
∗ When a "0" is written to the WAFG bit, provisionally the WAFG bit value is "0" and the /INT pin status is
OFF (Hi-z). However, as long as the WALE bit value is "1" the Alarm W function continues to operate, and
Alarm W occurs again the next time the same specified time arrives. You can stop Alarm W from
occurring by writing "0" to the WALE bit to set this function as invalid.
RX
-
4045
SA
/
NB
Page - 19 MQ442-01
3) /12, 24 bit
This bit is used to select between 12-hour clock operation and 24-hour clock operation.
/12,24 Data Description Address 2 (Hours register) data [h] during 24-hour and
12-hour clock operation modes
0 12-hour
clock
Write / Read
1 24-hour
clock
24-hour clock 12-hour clock 24-hour clock 12-hour clock
00 12 ( AM 12 ) 12 32 ( PM 12 )
01 01 ( AM 01 ) 13 21 ( PM 01 )
02 02 ( AM 02 ) 14 22 ( PM 02 )
03 03 ( AM 03 ) 15 23 ( PM 03 )
04 04 ( AM 04 ) 16 24 ( PM 04 )
05 05 ( AM 05 ) 17 25 ( PM 05 )
06 06 ( AM 06 ) 18 26 ( PM 06 )
07 07 ( AM 07 ) 19 27 ( PM 07 )
08 08 ( AM 08 ) 20 28 ( PM 08 )
09 09 ( AM 09 ) 21 29 ( PM 09 )
10 10 ( AM 10 ) 22 30 ( PM 10 )
11 11 ( AM 11 ) 23 31 ( PM 11 )
∗ Be sure to select between 12-hour and 24-hour clock operation before writing the time data.
4) Day setting
The following table shows the correspondence between the current day (W4, W2, W1) and the Alarm_W day
(WW6 to WW0). Be sure to set a "1" to the Alarm_W day when the alarm will occur. (An alarm will not occur for
any day that has a "0" setting.)
It is possible to enter settings for several days at the same time, in which case be sure to set a "1" for each day
(among WW6 to WW0) in which an alarm will occur.
Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
Alarm_W ; Day
□
WW6 WW5 WW4 WW3 WW2 WW1 WW0
Target day(s)
(W4,W2,W1) − Saturday
(1, 1, 0)
Friday
(1, 0, 1)
Thursday
(1, 0, 0)
Wednesday
(0, 1, 1)
Tuesday
(0, 1, 0)
Monday
(0, 0, 1)
Sunday
(0, 0, 0)
8.5.2. Alarm setting examples
Examples of settings for alarm usage are shown below.
Alarm_W
; Day
Day setting
Alarm_W
; Hour
Hour (hexadecimal)
Alarm_W
; Minute
Minute
(hexadecimal)
Alarm setting (example)
WW
6
Sat
WW
5
Fri
WW
4
Thu
WW
3
Wed
WW
2
Tue
WW
1
Mon
WW
0
Sun
24-hour
clock
12-hour
clock
12- & 24-hour
clock
Every day at 00:00 AM 1 1 1 1 1 1 100h hours 12h hours 00h min
Every day at 01:30 AM 1 1 1 1 1 1 101h hours 01h hours 30h min
Every day at 11:59 AM 1 1 1 1 1 1 111h hours 11h hours 59h min
Mon to Fri at 12:00 PM 0 1 1 1 1 1 012h hours 32h hours 00h min
Sunday at 01:30 PM 0 0 0 0 0 0 113h hours 21h hours 30h min
Mon/Wed/Fri at 11:59 PM 0 1 0 1 0 1 023h hours 31h hours 59h min
8.5.3. WAFG, DAFG and /INT, /INT output
∗ See "WAFG, DAFG and /INT, /INT output" in section 8.7.2.
RX
-
4045
SA
/
NB
Page - 20 MQ442-01
8.6. Alarm D function
The Alarm D function generates interrupt signals (output via the /INT pin) that correspond to specified hours and
minutes.
For description of the Alarm W function, which supports only day, hour, and minute data, see "8.5. Alarm W Function".
A polling function is also provided to enable checking of each alarm mode by the host.
8.6.1. Related registers
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
1
Minutes
!
M40 M20 M10 M8 M4 M2 M1
2
Hours
! !
H20
P , /A H10 H8 H4 H2 H1
B
Alarm_D ; Minute
!
DM40 DM20 DM10 DM8 DM4 DM2 DM1
C
Alarm_D ; Hour
! !
DH20
DP , /A DH10 DH8 DH4 DH2 DH1
Control 1
WALE
DALE /12 , 24
/CLEN2 TEST CT2 CT1 CT0
E
(Default) (0)
(0) (0)
( 0 ) ( 0 ) (0) (0) (0)
Control 2
VDSL VDET / XST PON /CLEN1 CTFG WAFG
DAFG
F
(Default) (0) (0) (−) ( 1 ) ( 0 ) (0) (0)
(0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
∗2) "
○
" indicates write-protected bits. A zero is always read from these bits.
∗3) "−" indicates undefined status.
• When the Alarm_D setting matches the current time, /INT pin is set to "L" and the DALE bit is set to "1".
Note: If the current date/time is used as the Alarm_D setting, the alarm will not occur until the counter counts up to
the current date/time (i.e., an alarm will occur next time, not immediately).
• During 24-hour clock operation, the "Alarm_D ; Hours" register's bit 5 (DH20, DP, /A) functions as DH20 (two-digit
hour display), and during 12-hour clock operation it functions as an AM/PM indicator.
1) DALE bit
This bit is used to set up the Alarm D function (to generate alarms matching hour or minute settings).
DALE Data Description
0 Alarm_D, match comparison operation invalid
∗ Default
Write / Read 1 Alarm_D, match comparison operation valid (/INT = "L" when
match occurs)
∗ When using the Alarm D function, first set this DALE bit value as "0," then stop the function. Next, set the
hour, minute, and the DAFG bit. Finally, set "1" to the DALE bit to set the Alarm D function as valid.
The reason for first setting the DALE bit value as "0" is to prevent /INT = "L" output in the event that a
match between the current time and alarm setting occurs while the alarm setting is still being made.
2) DAFG bit
This bit is valid only when the DALE bit value is "1". When a match occurs between the Alarm_D setting and the
current time, the DAFG bit value becomes "1" approximately 61 µs afterward. (There is no effect when the DALE
bit becomes "0".)
The /INT = "L" status that is set at this time can be set to OFF by writing a "0" to this bit.
DAFG Data Description
0
/INT pin = OFF (Hi-z) (only when periodic interrupt output is OFF)
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Alarm_D time setting does not match current time
(This bit's value is always "0" when the DALE bit's setting is "0")
∗ Default
Read
1
Alarm_D time setting matches current time
(result is that bit value is held until cleared to zero)
∗ When a "0" is written to the DAFG bit, provisionally the DAFG bit value is "0" and the /INT pin status is
OFF (Hi-z). However, as long as the DALE bit value is "1" the Alarm D function continues to operate, and
Alarm D occurs again the next time the same specified time arrives.
You can stop Alarm D from occurring by writing "0" to the DALE bit to set this function as invalid.
3) /12,24 bit
∗ See "/12, 24 bit" in section 8.5.1.3.
8.6.2. WAFG, DAFG and /INT, /INT output
∗ See "WAFG, DAFG and /INT output" in section 8.7.2.
RX
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4045
SA
/
NB
Page - 21 MQ442-01
8.7. /INT Output during Operation of Interrupt Function
8.7.1. Shared /INT output
The /INT interrupt output pin is shared as the output pin for interrupt events from three functions: the periodic
interrupt function, Alarm W function, and Alarm D function.
The /INT pin outputs at low level when any one of these interrupt events occurs.
When an interrupt has occurred (/INT = "L"), the CTFG, WAFG, and DAFG flags are read to determine which type of
interrupt event has occurred (indicated by a "1" value in the corresponding flag).
The /INT setting must be cleared via bit manipulation when another interrupt occurs or when the same interrupt
occurs again (this sets /INT to high impedance).
8.7.2. WAFG, DAFG, and /INT output
The following illustrates how the WAFG and DAFG bits relate to /INT output with regard to the operation of the
Alarm W function and Alarm D function.
/INTA, /INTB pins
61µs (approx)
Write "0" to WAFG
(DAFG)
WAFG (DAFG) bit
(Alarm/time match)
(Alarm/time match)
Write "0" to WAFG
(DAFG)
(Alarm/time match)
61µs (approx)
RX
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4045
SA
/
NB
Page - 22 MQ442-01
8.8. The various detection Functions
The detection functions include detection of power-on resets, oscillation stops, and supply voltage drops, as well as
reporting of detection results in corresponding bits of the address Fh (Control 2) register.
The status of the power supply, oscillation circuit, and clock can be confirmed by checking these results.
∗ Note with caution that detection functions may not operate correctly when power flickers occur.
8.8.1. Related register
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
F Control 2 VDSL VDET / XST PON
/CLEN1 CTFG WAFG DAFG
(Default)
(0) (0) (−
−−
−) (1)
( 0 ) (0) (0) (0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such as after powering up from 0 V or
recovering from a supply voltage drop.
∗2) '"−" indicates undefined status.
8.8.1. Power-on reset detection
This function detects when a power-on reset occurs. When a power-on reset is detected, the PON bit value becomes
"1".
A reset is detected when a power-on from 0 V has occurred, including when the power-on reset from 0 V occurred
due to a supply voltage drop.
1) PON bit
This bit indicates the detection results when a power-on reset has occurred.
The power-on reset function operates when a power-on from 0 V has occurred, including when a power-on reset
from 0 V occurred due to a supply voltage drop. When this function operates, the PON bit value becomes "1".
The /XST and VDET bits can be used in combination to determine the valid/invalid status of the clock and
calendar data.
PON Data Description
0
Clears PON bit to zero and sets up for next detection operation
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Power-on reset was not detected
Read
1
Power-on reset was detected
(result is that bit value is held until cleared to zero)
∗ Default
∗ When PON = "1" the clock precision adjustment register, Control register 1, and Control register 2 (except
for PON and /XST) are reset and cleared to "0". This stops (sets Hi-Z for) output from the /INT and /INT
pins.
2) Status of other bits when power-on reset is detected
• Internal initialization status during a power-on reset
Address Function bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
7 Digital Offset 0 F6 F5 F4 F3 F2 F1 F0
(Default) (0) (0) (0) (0) (0) (0) (0) (0)
E Control 1 WALE DALE /12, 24 /CLEN2 TEST CT2 CT1 CT0
(Default) (0) (0) (0)
( 0 ) ( 0 )
(0) (0) (0)
F Control 2 VDSL VDET / XST PON /CLEN1 CTFG WAFG DAFG
(Default) (0) (0) (−)
( 1 ) ( 0 )
(0) (0) (0)
∗1) The default value is the value that is read (or is set internally) after the PON bit has been set to "1," such
as after powering up from 0 V or recovering from a supply voltage drop.
∗2) " −" indicates undefined status.
∗3) At this point, all other register bits are undefined, so be sure to perform a reset before using the module.
Also, be sure to avoid entering incorrect date and time data, as clock operations are not guaranteed
when the time data is incorrect.
RX
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SA
/
NB
Page - 23 MQ442-01
8.8.2. Oscillation stop detection
This function detects when internal oscillation has stopped. When an oscillation stop is detected, the /XST bit value
becomes "0".
If a "1" has already been written to the /XST bit, the /XST bit is cleared to zero when stopping of internal oscillation is
detected, so this function can be used to determine whether or not an oscillation stop has occurred previously, such
as after recovery from a backup.
1) / XST bit
This bit indicates the oscillation stop detection function's detection results.
/ XST Data Description
0
Setting prohibited (do not set this bit value, even though it has no
effect)
Write
1
Sets the oscillation stop detection function as use-enabled and
sets up for next detection operation
0
Oscillation stop was detected
(result is that bit value is held until a "1" is written)
Read
1
Oscillation stop was not detected
2) Caution points
To prevent detection errors during operation of the oscillation stop detection
function, be sure to prevent stops due to V
DD
power flicker and prevent
application of voltage exceeding the maximum rated voltage to any pin.
In particular, fluctuation in the supply voltage may occur as shown in the figure
at right, such as when a back-up battery is used. If this occurs, internal data
may be lost even when the / XST bit value has not changed from "1" to "0" so
be sure to avoid any input that contains large amounts of chattering.
Example of voltage fluctuation that
makes oscillation stop hard to detect
V
DD
8.8.3. Voltage drop detection
This function detects when a voltage drop occurs. Detection of a voltage drop changes the VDET bit value to "1".
The threshold voltage value for detection can be set via the VDSL bit as 2.1 V or 1.3 V.
1) VDSL bit
This bit is used to set the power drop detection function's threshold voltage value.
VDSL Data Description
0 Sets 2.1 V as the power drop detection function's threshold
voltage value
∗ Default
Write / Read
1 Sets 1.3 V as the power drop detection function's threshold
voltage value
2) VDET bit
This bit indicates the power drop detection function's detection results. VDET = "1" once a power voltage drop
has occurred. This detection operation is then stopped and the bit value (1) is held.
VDET Data Description
0
Clears the VDET bit to zero, restarts the power drop detection
operation and sets up for next power drop detection operation
∗ Default
Write
1
Setting prohibited (do not set this bit value, even though it has no
effect)
0
Power drop was not detected
∗ Default
Read
1
Power drop was detected
(result is that bit value is held until cleared to zero)
3) Caution points
To reduce current
consumption while monitoring
the supply voltage, the supply
voltage monitor circuit
samples for only 7.8 ms
during each second, as
shown at right.
Sampling is stopped once the
VDET bit = "1". (Clear the
VDET bit to zero to resume
operation of the detection
function.)
VDET
(
D6 in address Fh
)
PON
VDD
2.1 V or 1.3 V
1 s
Write 0 to
VDET
7.8 ms
Sampling for supply
voltage monitoring
Internal initialization
period (1 to 2 s)
Write 0 to PON
& VDET
RX
-
4045
SA
/
NB
Page - 24 MQ442-01
8.8.4. Estimation of status based on detection results
The power supply status and clock status can be confirmed by reading the detection results indicated by the PON,
/XST, and VDET bits.
The following are status estimates based on various combinations of detection results.
Address F h
Control 2 Register Estimated status
bit 4 bit 5 bit 6
PON / XST VDET
Status of power supply and
oscillation circuit Status of clock and backup
0 0 0
• No supply voltage drop,
but oscillation has
stopped.
• Clock abnormality has occurred → Initialization is
required
∗ Clock has stopped temporarily, possibly due to
condensation.
0 0 1
• Supply voltage has
dropped and oscillation
has stopped.
• Clock abnormality has occurred → Initialization is
required
∗ Clock has stopped, perhaps due to drop in backup
power supply.
0 1 0 • Normal status.
• Normal status.
0 1 1
• Supply voltage has
dropped but oscillation
continues.
• Clock is normal, but an abnormality exists in the power
supply.
∗ Backup power supply may have dropped to a
hazardous level.
1 0
Χ
• Supply voltage has
dropped to 0 V.
1 1
Χ
• Power supply flickering is
likely.
• Initialization is required regardless of the clock status
and whether or not a voltage drop has occurred.
∗ Initialization is required due to bits that are reset
when PON = "1".
∗ The example shown above is when a "1" has already been written to /XST.
32768-Hz oscillation
Power-on reset (PON)
Oscillation stop detection
(/XST)
Threshold voltage ( 2.1 V or 1.3 V )
Normal voltage detector
VDET←0
/XST←1
Supply voltage
PON,VDET←0
/XST←1
Sup pl y v oltage mo ni t o r
(VDET)
Internal initialization
period (1 to 2 s)
PON, VDET←0
/XST←1
Internal initialization
period (1 to
2 s)
RX
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4045
SA
/
NB
Page - 25 MQ442-01
8.9. Read/Write of Data
8.9.1. Data transfer method
1) CE and data capture timing
The RX-4045 uses a four-line serial interface to transfer data across four pins: CE (chip enable), CLK (serial
clock), DI (data input), and DO (data output).
For data transfers, select between two methods for clock timing of the DI and DO signals: "capture at falling
edge and output at rising edge" or "capture at rising edge and output at falling edge".
(1) Capture data at falling edge and output at rising edge
When the CE signal goes from low to high, if CLK is low, the data is captured at the falling edge and
output at the rising edge.
CLK
DO
t
DS
DI
CE t
CES
t
DH
t
RD
" L "
(2) Capture data at rising edge and output at falling edge
When the CE goes from low to high, if CLK is H, the data is captured at the rising edge and output at
the falling edge.
CLK
DO
t
DS
DI
CE t
CES
t
DH
t
RD
" H "
2) Data transfer format
Data transfer starts at the rising edge and ends at the falling edge of CE input.
Each byte (8 bits) is handled as a unit, and any number of bytes can be transferred consecutively.
The start address for starting transfer from the host is specified (as an address pointer setting) in the first four
bits of the first byte. A transfer format register setting in the second four bits determines whether data will be
written or read and which transfer format will be used.
All transfers are performed in MSB-first order.
A2
CE
CL
K
DO
6
A1 A0 C3 C2 C1 C0
D7 D6 D3 D2 D1 D0
A3
7582312 3 1 4
D7 D6 D3 D2 D1 D0
Address pointer
setting
When data is written
Transfer format
register setting
DI
When data is read
* There are two transfer methods each for read and write operations.
RX
-
4045
SA
/
NB
Page - 26 MQ442-01
8.9.2. Write methods for data transfer
1) Single-byte write method
The first data write method transfers each byte of data independently.
The target address for writing is specified by the address pointer and "8h" is written to the transfer format
register.
After one byte of data has been transferred, the transfer can be terminated by setting the CE pin to low level,
or the transfer operation can be continued by specifying a new target address and transfer format.
1 1 Data
Data
Example of data write (to addresses Fh and 7h)
Host-side transmitter
CE
RTC-side transmitter
DO
7h is set
to
address
pointer
0 1 0 0 1 1
Data is written to
address Fh
Data is written to
address 7h
0 11 0 0 0 1 1
Fh is set to
address
pointer
8h is set
to transfer
format
register
DI
8h is se
t
to transfe
r
format
register
2) Burst write method
The second data write method transfers data consecutively.
The target address for writing is specified by the address pointer and "0h" is written to the transfer format
register.
The address pointer is incremented each time a byte is transferred. The next address pointer value after Fh is
0h.
Lastly, the transfer is terminated by setting the CE pin to low level.
1 0 Data
Data
Example of data write (to addresses
Eh, Fh, and 0h)
Host-side transmitter
CE
DO
0 0 0 0 1 1
Data is written to
address Fh
Data is written to
address 0h
Eh is set to
address
pointer
0h is set
to transfer
format
register
Data is written to
address Eh
DI Data
RTC-side transmitter
RX
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4045
SA
/
NB
Page - 27 MQ442-01
8.9.3. Read methods for data transfer
1) Single-byte read method
The first data read method transfers each byte of data independently.
The target address for reading is specified by the address pointer and "Ch" is written to the transfer format
register.
After one byte of data has been transferred, the transfer can be terminated by setting the CE pin to low level,
or the transfer operation can be continued by specifying a new target address and transfer format.
1 0
Data
Data
Example of data read (from addresses
Eh and 2h)
CE
DO
2h is set
to
address
pointer
1 1 0 0 1 1
Ch is set
to transfe
r
format
re
g
ister
Data is read from
address Eh
Data is read from
address 2h
0 10 1 0 00 1
Eh is set to
address
pointer
Ch is set to
transfer
format
re
g
ister
DI
Host-side transmitter
RTC-side transmitter
2) Burst read method
The second data read method transfers data consecutively.
The target address for writing is specified by the address pointer and "4h" is written to the transfer format
register. The address pointer is incremented each time a byte is transferred.
The next address pointer value after Fh is 0h.
Lastly, the transfer is terminated by setting the CE pin to low level.
1 1
Data
Data
Example of data read (from addresses Fh, 0h, and 1h)
CE
DO
1 0 0 0 1 1
Data is read from
address 0h
Data is read from
address 1h
Fh is set to
address
pointer
4h is set to
transfer
format
register
Data
Data is read from
address Fh
DI
Host-side transmitter
RTC-side transmitter
3) Consecutive read and consecutive write
After reading one byte or writing one byte, this method enables another transfer to be performed
consecutively.
1 1
Data
Example of consecutive data read/write (reading and writing of data at address Fh)
CE
DO
Fh is set
to
address
pointer
1 1 0 0 1 1
8h is set
to transfe
format
register
Read data at
address Fh
Write data to
address Fh
1 11 0 0 01 1
Fh is set to
address
pointer
Ch is set
to transfer
format
register
Data
DI
Host-side transmitter
RTC-side transmitter
* The following table provides a summary of the relation between the read/write format and settings in the transfer
format register.
Single byte Burst
(consecutive)
Write to RTC 8h (1,0,0,0) 0h (0,0,0,0)
Read from RTC Ch (1,1,0,0) 4h (0,1,0,0)
RX
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SA
/
NB
Page - 28 MQ442-01
8.9.4. Caution points on read/write of time data
If the time value is changed across several digits during a time read/write operation, an incorrect time value may
be read or written.
For example, if a read operation is started when the time value is 13:59:59 and the timer's value changes from
13:59:59 to 14:00:00 while the time value is being read (sequentially from seconds to minutes to hours), the read
values for "seconds" and "minutes" may be each "59" while the read value for "hours" may be "14", resulting in a
read time value of 14:59:59, which is off by one hour. Similar errors can occur when writing time values.
The RX-4045 prevents these types of read/write errors by setting the time value incrementation function on hold
while the CE pin is at high level (the hold is canceled and incrementation resumes when the CE pin returns to low
level).
Since the hold function operates only for one second, the CE pin must return to low level within one second.
CE
Time in RTC
14:00:01
Actual time
13:59:59
Max. 39 µs
14:00:00
13:59:59 14:00:00 14:00:01
Note the following caution points when using this function while reading or writing time values.
(1) Keep the CE pin at high level while reading or writing one time value.
(2) The period during which CE = H should not exceed one second. Due to the remote possibility that the host
system may go down while reading or writing a time value, a peripheral circuit should be implemented to set CE
as either low or open as soon as such an event occurs.
(3) After CE has been switched from low to high, leave a time interval of at least 31 µs before accessing any
address from 0h to 6h. (This allows time for completion of any incrementation of two digits or more in the time
value that the RX-4045 might be performing.)
(4) After CE has been switched from high to low, leave a time interval of at least 61 µs before CE is switched high
again. (This allows the RX-4045 to correct the time value if the value was due to change while CE = H.)
(5) The above caution points do not have to be considered as long as time read/write operations are clearly set so
as to avoid time value incrementation of two or more digits (such as by timing the read/write operation to
coincide with level-mode periodic interrupts or alarm interrupts.)
* Correct and incorrect examples of time read/write operations are illustrated on the next page.
RX
-
4045
SA
/
NB
Page - 29 MQ442-01
DO
0Ch
Data
Data
Address 0h
(seconds) is
read
Incorrect example 1: CE is set low once while reading the time value.
Address pointer = 0h
Transfer form at
register = C h
Less than 61µs
Address 0h
(seconds) is
read
DO
F0h
Write to
address 2h
(hours)
CE
Address point er = F h
Transfer form at
register = 0h
Less than 31µs
Write to
address 0h
(seconds)
Write to
Address Fh
(control 2)
Write to
address 1h
(minutes)
0Ch
Address pointer = 0h
Transfer form at
register = C h
CE
Incorrect example 3: If interval between two time read operations is less than 61 µs
Correct example
DO Data
F4h
Data
Data
Address 2h
(hours) is
read
CE
Address point er = F h
Transfer form at
register = 4h
31 µs or more
Address 0h
(seconds) is
read
Address Fh
(control 2) is
read
Data
Address 1h
(minutes) is
read
DO
0Ch
Data
Data
Address 2h
(hours) is
read
Address pointer = 1h
Transfer form at
register = 4h
31 µs or more
Address 0h
(seconds) is
read
Data
Address 1h
(minutes) is
read
14h
Address pointer = 0h
Transfer form at
register = C h
31 µs or more
CE
RTC-side transmitter
0Ch
DataHost-side transmitter
Incorrect example 2: If interval is less than 31 µs when time write operation is started
When not f or address 0h t o 6h, read/ wri te can
be perform ed wi thout a 31-µs interval.
DI
DI
DI
DI
Data Data Data
Data
RX
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4045
SA
/
NB
Page - 30 MQ442-01
8.10. External Connection Example
System Power Supply
V
DD
/ INT
Pull Up R
RX - 4045
CE
GND
CLK
DI
DO
FOUT
Primary
Battery
Note 3
Note 4
Note 1
Note 2
Note 1
FOUT and INT terminal is Nch-Open Drain output, and the protective diode doesn't exist in Vdd side.
Therefore pull up is possible to 5.5 V without relation of the power supply voltage of this device.
Pull up resistor is connected to system power supply when doesn't use the output signal in backup.
Pull up resistor is connected to backup power supply when using the output signal in backup.
In case of both, be careful with a current of resistor.
Note 2
RTC module recommends that you installs the two capacitors for low frequency and high frequency in
closest to the RTC.
Note 3
Maintain the voltage of DO terminal lower than VDD + 0.3 V which is maximum rating absolutely when
supply a power supply of this device with diode OR.
Note 4
Warn the following points, about connection of CE-terminal.
When a power supply voltage rises from 0 V or the host side power is downed, CE = L or open.
VDD
CE
Lower operating voltage of the Controller.
↑ Back Up Voltage
0.2 × VDD
Min. 0 µs Min. 0 µs
Min. 0 µs
RX
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SA
/
NB
Page - 31 MQ442-01
9. External Dimensions / Marking Layout
9.1. External Dimensions
RX-4045 SA
(SOP-14pin)
• External dimensions • Recommended soldering
0.6
0.15
0° - 10°
1.4
1.4
5.4
1.27
1.27 × 6 = 7.62
0.7
Unit : mm
10.1
±
0.2
5.0 7.4
±
0.2
#14 #8
#7
#1
1.27 1.2
0.05
Min. 3.2
±
0.1
0.35
∗ The cylinder of the crystal oscillator can be seen in this area ( back and front ),
but it has no affect on the performance of the device.
RX-4045 NB
(SON-22pin)
• External dimensions •Solderin
g
p
attern
1.3 ± 0.1
0.125
0.1
Unit : mm
6.3 Max.
5.0 ± 0.2
4.8
0.5 0.2
# 1
# 22
# 14
# 11
# 14
(0.3)
# 11 # 1
# 22
0.8
P 0.5 ×10 = 5.0
1.4
0.5
5.25
0.25
0.7
0.75 0.25
0.8
0.7
4.0 0.7 0.7
#1
# 11
#22 #14
∗
1)
The cylinder of the crystal oscillator can be seen in this area ( back and front ),
but it has no affect on the performance of the device.
∗
2)
In this area, At a parts side of electronic base, you must not do layout any signal line.
9.2. Marking Layout
RX - 4045 SA
(SOP-14pin)
Logo
Type
Production lot
R 4025
E A123B
RX - 4045 NB
(SON-22pin)
Logo
Type
Production lot
E
A
123B
R4025
∗ The layout shown above is a simplified drawing of the seal and label. Details such as the fonts, sizes, and positioning of
label contents are not necessarily as shown.
RX
-
4045
SA
/
NB
Page - 32 MQ442-01
10. Reference Data
[Finding the frequency stability]
1. Frequency and temperature characteristics can be
approximated using the following equations.
∆f
T
= α (θ
T
- θ
X
)
2
∆f
T
: Frequency deviation in any
temperature
α (1 / °C
2
): Coefficient of secondary temperature
(−0.035±0.005) × 10
-6
/ °C
2
θ
T
(°C) : Ultimate temperature (+25±5 °C)
θ
X
(°C) : Any temperature
2. To determine overall clock accuracy, add the frequency
precision and voltage characteristics.
∆f/f
= ∆f/fo + ∆f
T
+ ∆f
V
∆f/f : Clock accuracy (stable frequency) in any
temperature and voltage
∆f/fo : Frequency precision
∆f
T
: Frequency deviation in any temperature
∆f
V
: Frequency deviation in any voltage
3. How to find the date difference
Date difference = ∆f/f × 86400 (seconds)
* For example: ∆f/f = 11.574 × 10
-6
is an error of
approximately 1 second/day.
(1) Example of frequency and temperature characteristics
-150
-100
-50
0
-50 0 +50 +100
Temperature [°C]
Frequency
∆
f
T
× 10
-6
θ
T
= +25 °C Typ.
α = -0.035 × 10
-6
Typ.
(2) Example of frequency and voltage characteristics
- 3
2
Frequency ∆f
v
× 10
−6
+ 3
0
3 4 5
Condition :
3 V as reference, Ta=+25 °C
Supply Voltage V
DD
[V]
(3) Current and voltage consumption characteristics
Current consumption when non-accessed (i)
when FOUT=OFF
2
Current consumption [µA]
Supply Voltage V
DD
[V]
1.0
0.5
3 4 5
Condition :
Ta = +25 °C
CE = GND
INT = V
DD
FOUT ; Output OFF
RX
-
4045
SA
/
NB
Page - 33 MQ442-01
11. Application notes
1) Notes on handling
This module uses a C-MOS IC to realize low power consumption. Carefully note the following cautions when handling.
(1) Static electricity
While this module has built-in circuitry designed to protect it against electrostatic discharge, the chip could still be damaged by a
large discharge of static electricity. Containers used for packing and transport should be constructed of conductive materials. In
addition, only soldering irons, measurement circuits, and other such devices which do not leak high voltage should be used with
this module, which should also be grounded when such devices are being used.
(2) Noise
If a signal with excessive external noise is applied to the power supply or input pins, the device may malfunction or "latch up." In
order to ensure stable operation, connect a filter capacitor (preferably ceramic) of greater that 0.1F as close as possible to the
power supply pins (between VDD and GNDs). Also, avoid placing any device that generates high level of electronic noise near
this module.
* Do not connect signal lines to the shaded area in the figure shown in Fig. 1 and, if possible, embed this area in a GND land.
(3) Voltage levels of input pins
When the input pins are at the mid-level, this will cause increased current consumption and a reduced noise margin, and can
impair the functioning of the device. Therefore, try as much as possible to apply the voltage level close to VDD or GND.
(4) Handling of unused pins
Since the input impedance of the input pins is extremely high, operating the device with these pins in the open circuit state can
lead to unstable voltage level and malfunctions due to noise. Therefore, pull-up or pull-down resistors should be provided for all
unused input pins.
2) Notes on packaging
(1) Soldering heat resistance.
If the temperature within the package exceeds +260 °C, the characteristics of the crystal oscillator will be degraded and it may
be damaged. The reflow conditions within our reflow profile is recommended. Therefore, always check the mounting
temperature and time before mounting this device. Also, check again if the mounting conditions are later changed.
* See Fig. 2 profile for our evaluation of Soldering heat resistance for reference.
(2) Mounting equipment
While this module can be used with general-purpose mounting equipment, the internal crystal oscillator may be damaged in
some circumstances, depending on the equipment and conditions. Therefore, be sure to check this. In addition, if the mounting
conditions are later changed, the same check should be performed again.
(3) Ultrasonic cleaning
Depending on the usage conditions, there is a possibility that the crystal oscillator will be damaged by resonance during
ultrasonic cleaning. Since the conditions under which ultrasonic cleaning is carried out (the type of cleaner, power level, time,
state of the inside of the cleaning vessel, etc.) vary widely, this device is not warranted against damage during ultrasonic
cleaning.
(4) Mounting orientation
This device can be damaged if it is mounted in the wrong orientation. Always confirm the orientation of the device before
mounting.
(5) Leakage between pins
Leakage between pins may occur if the power is turned on while the device has condensation or dirt on it. Make sure the device
is dry and clean before supplying power to it.
Fig. 1 : Example GND Pattern
Fig. 2 : Reference profile for our evaluation of Soldering heat resistance.
RX - 4045 SA
( SOP-14pin )
RX - 4045 NB
( SON-22pin )
+1 ∼ +5 °C/ s
100 s
Pre-heating area
−1 ∼ −5 °C / s
time [ s ]
Temperature [ °C ]
+170 °C +220
°C
+260 °C Max.
+1 ∼ +5 °C / s
35 s
Stable Melting area
∗ In addition, please confirm the Notes of an individual specification.
Application Manual
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