S-35390A
www.sii-ic.com 2-WIRE REAL-TIME CLOCK
© Seiko Instruments Inc., 2004-2011 Rev.4.0_00
Seiko Instruments In c. 1
The S-35390A is a CMOS 2-wire real-time clock IC which operates with the very low current consumption and in the wide
range of operation voltage. The operation voltage is 1.3 V to 5.5 V so that the S-35390A can be used for various power
supplies from main supply to backup battery. Due to the 0.25 μA current consumption and wide range of power supply voltage
at time keeping, the S-35390A makes the battery life longer. In the system which operates with a backup battery, the included
free registers can be used as the function for user’s backup memory. Users always can take back the information in the
registers which is stored before po wer-off the main power supply, after the voltage is restored.
The S-35390A has the function to correct advance / delay o f the clock data speed, i n the wide rang e, which is caused b y the
oscillation circuit’s frequency deviation. Correcting according to the temperature change by combining this function and a
temperature sensor, it is possible to make a high precise clock function which is not affected by the ambient temperature.
Features
• Low current consumption: 0.25 μA typ. (VDD = 3.0 V, Ta = +25°C)
• Wide range of operating voltage: 1.3 V to 5.5 V
• Built-in clock correction function
• Built-in free user register
• 2-wire (I2C-bus) CPU interface
• Built-in alarm interrupter
• Built-in flag generator during detectio n of low power voltage or at power-on
• Auto calendar up to the year 209 9, autom atic leap year calculation function
• Built-in constant voltage circuit
• Built-in 32.768 kHz crystal oscillator (Cd built in, Cg external)
• Lead-free, Sn 100%, halogen-free*1
*1. Refer to " Product Name Structure" for details.
Applications
• Mobile game device
• Mobile AV device
• Digital still camera
• Digital video camera
• Electronic power meter
• DVD recorder
• TV, VCR
• Mobile phone, PHS
• Car navigation system
Packages
• 8-Pin SOP (JEDEC)
• 8-Pin TSSOP
• SNT-8A
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
2
Block Diagram
Real-time data register
Status register 1
Oscillator
SCL
SDA
Low power supply
voltage detector
VDD
VSS
Comparator 1
Shift register Serial
interface
XIN
XOUT
INT2
Comparator 2
Clock correction register
INT1
controller
Diviver,
timing generator
INT2
controller
Constant-voltage
circuit
Status register 2
INT1 register
INT2 register
Power-on
detection circuit
Free register
INT1
Day Month Year
Day of
the week
Minute
Hour
Second
Figure 1
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 3
Product Name Structure
1. Product name
S-35390A - xxxx x
Product name
Environmental code
U: Lead-free (Sn 100%), halogen-free
G: Lead-free (for details, please contact our sales office)
Package name (abbreviation) and IC packing specification*1
J8T1: 8-Pin SOP (JEDEC), Tape
T8T1: 8-Pin TSSOP, Tape
I8T1: SNT-8A, Tape
*1. Refer to the tape drawing.
2. Packages
Table 1 Package Drawing Codes
Package Name Dimension Tape Reel Land
Environmental code = G FJ008-A-P-SD FJ008-D-C-SD FJ008-D-R-SD −
8-Pin SOP (JEDEC) Environmental code = U FJ008-A-P-SD FJ008-D-C-SD FJ008-D-R-S1 −
Environmental code = G FT008-A-P-SD FT008-E-C-SD FT008-E-R-SD −
8-Pin TSSOP Environmental code = U FT008-A-P-SD FT008-E-C-SD FT008-E-R-S1 −
SNT-8A PH008-A-P-SD PH008-A-C-SD PH008-A-R-SD PH008-A-L-SD
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
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Pin Configurations
Table 2 List of Pins
Pin No Symbol Description I/O Configuration
1 1INT Output pin for
interrupt signal 1 Output Nch open-drain out put
(no protective diode at VDD)
2 XOUT
3 XIN
Connection pin
for crystal
oscillator − −
4 VSS GND pin − −
5 2INT Output pin for
interrupt signal 2 Output Nch open-drain output
(no protective diode at VDD)
6 SCL Input pin for
serial clock Input CMOS input
(no protective diode at VDD)
7 SDA I/O pin for serial
data Bi-directional Nch open-drain output
(no protective diode at VDD)
CMOS input
8 VDD Pin for positive
power supply − −
1. 8-Pin SOP (JEDEC)
7
6
5
8
2
3
4
1
Top view
Figure 2 S-35390A-J8T1x
2. 8-Pin TSSOP
7
6
5
8
2
3
4
1
Top view
Figure 3 S-35390A-T8T1x
3. SNT-8A
7
6
5
8
2
3
4
1
Top view
Figure 4 S-35390A-I8T1x
Remark 1. x: G or U
2. Please select products of environmental code = U for Sn 100%, halogen-free products.
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 5
Pin Functions
1. SDA (I/O for serial data) pin
This is a data input / output pin of I2C-bus interface. T his pin inputs / outputs data by synchronizing with a clock pulse
from the SCL pin. This pin has CMOS input and Nch open drain output. Generall y in use, pull up this pin to the VDD
potential via a resistor, and connect it to any other device having open drain or open collector output with wired-OR
connection.
2. SCL (input for serial clock) pin
This pin is to input a clock pulse for I2C-bus interface. The SDA pin inputs / outputs data by synchronizing with the
clock pulse.
3. XIN, XOUT (crystal oscillator connect) pin
Connect a crystal oscillator between XIN and XOUT.
4. INT1 (output for interrupt signal 1) pin
This pin outputs a signal of interrupt, or a clock pulse. By using the status register 2, users can select either of; alarm 1
interrupt, output of user-set frequency, minute-periodical interrupt 1, minute-periodical interrupt 2, or 32.768 kHz output.
This pin has Nch open drain output.
5. INT2 (output for interrupt signal 2) pin
This pin outputs a signal of interrupt, or a clock pulse. By using the status register 2, users can select either of; alarm 2
interrupt, output of user-set frequency, or minute-periodical interrupt 1. This pin has Nch open drain output.
6. VDD (positive power supply ) pin
Connect this VDD pin with a positive power supply. Regarding the values of voltage to be applied, refer to
" Recommended Operation Conditions".
7. VSS pin
Connect this VSS pin to GND.
Equivalent Circuits of Pins
SDA
Figure 5 SDA Pin
SCL
Figure 6 SCL Pin
INT1, INT2
Figure 7 INT1 Pin, INT2 Pin
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
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Absolute Maximum Ratings
Table 3
Item Symbol Applied Pin Absolute Maximum Rating Unit
Power supply voltage VDD − V
SS − 0.3 to VSS + 6.5 V
Input voltage VIN SCL, SDA VSS − 0.3 to VSS + 6.5 V
Output voltage VOUT SDA, INT1, INT2 VSS − 0.3 to VSS + 6.5 V
Operating ambient
temperature*1 Topr − −40 to +85 °C
Storage temperature Tstg − −55 to +125 °C
*1. Conditions with no condensati on or frost. Condensation an d frost cause short circuiting bet ween pins, resulting in a
malfunction.
Caution The absolute maximum ratings are rated values exceeding which the product could suffer physical
damage. These values must therefore not be exceeded under any condition s.
Recommended Operation Conditions
Table 4 (VSS = 0 V)
Item Symbol Condition Min. Typ. Max. Unit
Power supply voltage*1 VDD Ta = −40°C to +85°C 1.3 3.0 5.5 V
Time keeping power
supply voltage*2 VDDT Ta = −40°C to +85°C VDET − 0.15 − 5.5 V
Crystal oscillator CL value CL − − 6 7 pF
*1. The power supply voltage that allows communication under the conditions shown in Ta ble 9 of " AC Electrical
Characteristics".
*2. The power supply voltage that allows time keeping. For the relationship with VDET (low power supply voltage detection
voltage), refer to " Characteristics (Typical Data)".
Oscillation Characteristics
Table 5
(Ta =
+
25
°
C, V
DD
= 3.0 V, V
SS
= 0 V, VT-200 crystal oscillator (C
L
= 6 pF, 32.768 kHz) manufactured by Seiko Instruments Inc.)
Item Symbol Condition Min. Typ. Max. Unit
Oscillation start voltage VSTA Within 10 seconds 1.1 − 5.5 V
Oscillation start time tSTA − − − 1 s
IC-to-IC frequency
deviation*1 δIC − −10 − +10 ppm
Frequency voltage
deviation δV VDD = 1.3 V to 5.5 V −3 − +3 ppm/V
External capacitance Cg Applied to XIN pin − − 9.1 pF
Internal oscillation
capacitance Cd Applied to XOUT pin − 8 − pF
*1. Reference value
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 7
DC Electrical Characteristics
Table 6 DC Characteristics (VDD = 3.0 V)
(Ta
=
−
40
°
C to
+
85
°
C, V
SS
= 0 V,VT-200 crystal oscillator (C
L
= 6 pF, 32.768 kHz, C
g
= 9.1 pF) manufactured by Seiko Instruments Inc.)
Item Symbol Applied Pin Condition Min. Typ. Max. Unit
Current consumption 1 IDD1 − Out of communication − 0.25 0.93 μA
Current consumption 2 IDD2 − During communication
(SCL = 100 kHz) − 6 14 μA
Input current leakage 1 IIZH SCL, SDA VIN = VDD −0.5 − 0.5 μA
Input current leakage 2 IIZL SCL, SDA VIN = VSS −0.5 − 0.5 μA
Output current leakage 1 IOZH SDA, 1INT ,
2INT VOUT = VDD −0.5 − 0.5 μA
Output current leakage 2 IOZL SDA, 1INT ,
2INT VOUT = VSS −0.5 − 0.5 μA
Input voltage 1 VIH SCL, SDA − 0.8 × VDD − V
SS + 5.5 V
Input voltage 2 VIL SCL, SDA − V
SS − 0.3 − 0.2 × VDD V
Output current 1 IOL1 1INT , 2INT VOUT = 0.4 V 3 5 − mA
Output current 2 IOL2 SDA VOUT = 0.4 V 5 10 − mA
Power supply voltage
detection voltage VDET − − 0.65 1 1.35 V
Table 7 DC Characteristics (VDD = 5.0 V)
(Ta
=
−
40
°
C to
+
85
°
C, V
SS
= 0 V, VT-200 crystal oscillator (C
L
= 6 pF, 32.768 kHz, C
g
= 9.1 pF) manufactured by Seiko Instruments Inc.)
Item Symbol Applied Pin Condition Min. Typ. Max. Unit
Current consumption 1 IDD1 − Out of communication − 0.3 1.1 μA
Current consumption 2 IDD2 − During communication
(SCL = 100 kHz) − 14 30 μA
Input current leakage 1 IIZH SCL, SDA VIN = VDD −0.5 − 0.5 μA
Input current leakage 2 IIZL SCL, SDA VIN = VSS −0.5 − 0.5 μA
Output current leakage 1 IOZH SDA, 1INT ,
2INT VOUT = VDD −0.5 − 0.5 μA
Output current leakage 2 IOZL SDA, 1INT ,
2INT VOUT = VSS −0.5 − 0.5 μA
Input voltage 1 VIH SCL, SDA − 0.8 × VDD − V
SS + 5.5 V
Input voltage 2 VIL SCL, SDA − V
SS − 0.3 − 0.2 × VDD V
Output current 1 IOL1 1INT , 2INT VOUT = 0.4 V 5 8 − mA
Output current 2 IOL2 SDA VOUT = 0.4 V 6 13 − mA
Power supply voltage
detection voltage VDET − − 0.65 1 1.35 V
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
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AC Electrical Characteristics
Table 8 Measurement Conditions
Input pulse voltage VIH = 0.9 × VDD, VIL = 0.1 × VDD
Input pulse rise / fall time 20 ns
Output determination voltage VOH = 0.5 × VDD, VOL = 0.5 × VDD
Output load 100 pF + pull-up resistor 1 kΩ
SDA
C = 100 pF
V
DD
R = 1 kΩ
Remark The power supplies of the IC
and load have the same
electrical potential.
Figure 8 Output Load Circuit
Table 9 AC Electrical Characteristics (Ta = −40°C to +85°C)
VDD*2 ≥ 1.3 V VDD*2 ≥ 3.0 V
Item Symbol
Min. Typ. Max. Min. Typ. Max.
Unit
SCL clock frequency fSCL 0 − 100 0 − 400 kHz
SCL clock low time tLOW 4.7 −
− 1.3 −
− μs
SCL clock high time tHIGH 4 − − 0.6 − − μs
SDA output delay time*1 tPD − − 3.5 − − 0.9 μs
Start condition setup time tSU.STA 4.7 − − 0.6 − − μs
Start condition hold time tHD.STA 4 −
−
0.6 −
−
μs
Data input setup time tSU.DAT 250 − − 100 − − ns
Data input hold time tHD.DAT 0 − − 0 − − μs
Stop condition setup time tSU.STO 4.7 − − 0.6 − − μs
SCL, SDA rise time tR − − 1 − − 0.3 μs
SCL, SDA fall time tF − −
0.3 − −
0.3 μs
Bus release time tBUF 4.7 − − 1.3 − − μs
Noise suppression time tI − − 100 − − 50 ns
*1. Since the output format of the SDA pin is Nch open-drai n output, SDA output delay time is determined by the values of
the load resistance (RL) and load capacity (CL) outside the IC. Therefore, use this value only as a reference value.
*2. Regarding the po wer suppl y voltage, refer to " Recommended Operation Conditions".
SCL
SDA
(Input from
S-35390A)
SDA
(Output from
S-35390A)
tBUF
tR
tSU.STO
tSU.DAT
tHD.DAT
tPD
tHIGH tLOW
t
HD.STA
tSU.STA
tF
Figure 9 Bus Timing
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 9
Configuration of Data Communication
1. Data communication
For data communication, the master device in the system generates a start condition for the S-35390A. Next, the
master device tr ansmits 4-bit device cod e "0 110", 3-bit com mand an d 1-bit read / write command to t he SDA line. After
that, output or input is perf ormed from B7 of data. I f data I/O has been co mpleted, finish communic ation by in putting a
stop condition to the S-35390A. The master device generates an acknowledgment signal for every 1-byte. Regarding
details, refer to " Serial Interface".
Command
0 1 1 0 C2 C1 C0 R / W
Device code
ACK
Read / write bit
Acknowledgment bit
B7 B6 B5 B4 B3 B2 B1 B0 ACK
Start condition
Stop condition
1-byte data
STA
STP
Figure 10 Data Communication
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
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2. Configuration of command
8 types of command are available for the S-35390A. The S-35390A reads / writes the various registers by inputting
these codes and commands. The S-35390A does not perfor m any operat ion with any co des and comma nds other than
those below.
Table 10 List of Commands
Command
Data
Device
Code
C2 C1 C0
Description
B7 B6 B5 B4 B3 B2 B1 B0
0 0 0
Status regist er 1 access
RESET
*1 24 / 12 SC0*2 SC1*2 INT1*3 INT2*3 BLD*4 POC*4
0 0 1
Status regist er 2 access INT1FE INT1ME INT1AE
32kE
INT2FE
INT2ME INT2AE
TEST*5
0 1 0
Real-time data 1 access
(year data to)
Y1
M1
D1
W1
H1
m1
s1
Y2
M2
D2
W2
H2
m2
s2
Y4
M4
D4
W4
H4
m4
s4
Y8
M8
D8
−*6
H8
m8
s8
Y10
M10
D10
−*6
H10
m10
s10
Y20
−*6
D20
−*6
H20
m20
s20
Y40
−*6
−*6
−*6
PM / AM
m40
s40
Y80
−*6
−*6
−*6
−*6
−*6
−*6
0 1 1
Real-time data 2 access
(hour data to)
H1
m1
s1
H2
m2
s2
H4
m4
s4
H8
m8
s8
H10
m10
s10
H20
m20
s20
PM / AM
m40
s40
−*6
−*6
−*6
INT1 register access
(alarm time 1: week / hour / minute)
(INT1AE = 1, INT1ME = 0,
INT1FE = 0)
W1
H1
m1
W2
H2
m2
W4
H4
m4
−*6
H8
m8
−*6
H10
m10
−*6
H20
m20
−*6
PM / AM
m40
A1WE
A1HE
A1mE
1 0 0
INT1 register access
(output of user-set frequency)
(INT1ME = 0, INT1FE = 1)
1 Hz 2 Hz 4 Hz 8 Hz 16 Hz SC2*2 SC3*2 SC4*2
INT2 register access
(alarm time 2: week / hour / minute)
(INT2AE = 1, INT2ME = 0,
INT2FE = 0)
W1
H1
m1
W2
H2
m2
W4
H4
m4
−*6
H8
m8
−*6
H10
m10
−*6
H20
m20
−*6
PM / AM
m40
A2WE
A2HE
A2mE
1 0 1
INT2 register access
(output of user-set frequency)
(INT2ME = 0, INT2FE = 1)
1 Hz 2 Hz 4 Hz 8 Hz 16 Hz SC5*2 SC6*2 SC7*2
1 1 0
Clock correction register access
V0 V1 V2 V3 V4 V5 V6 V7
0110
1 1 1
Free register access
F0 F1 F2 F3 F4 F5 F6 F7
*1. Write-only flag. The S-35390A initializes by writing "1" in this register.
*2. Scratch bit. This is a register which is available for read / write operations and can be used by users freely.
*3. Read-only fla g. Valid only when using t he alarm function. W hen the alarm time matches, this flag is set to "1", an d it is
cleared to "0" when reading.
*4. Read-only flag. "POC" is set to "1" when power is applied. It is cleared to "0" when reading. Regarding "BLD", refer to
" Low Power Supply Voltage Detection Circuit".
*5. Test bit for SII. Be sure to set to "0" in use.
*6. No effect when writing. It is "0" when reading.
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 11
Configuration of Registers
1. Real-time data register
The real-time data register is a 7-byte register that stores the data of year, month, day, day of the week, hour, minute,
and second in the BCD code. To write / read real-time data 1 access, transmit / receive the data of year i n B7, month,
day, day of the week, hour, minute, second in B0, in 7-byte. When you skip the procedur e to access the data of year,
month, day, day of the week, read / write real-time data 2 accesses. In this case, transmit / receive the data of hour in B7,
minute, second in B0, in 3-byte.
The S-35390A transfers a set of data of time to the real-time data register when it recognizes the read command.
Therefore, the S-35390A keeps precise time even if time-carry occurs during the read operation of real-time data
register.
Year data (00 to 99)
Month data (01 to 12)
Day data (01 to 31)
Hour data (00 to 23 or 00 to 11)
Minute data (00 to 59)
Second data (00 to 59)
Y80
Y40
Y4 Y8 Y10 Y20
Y2
Y1
B7 B0
M1 M2 M4 M8 M10 0 0 0
D1 D2 D4 D8 D10 D20 0 0
W1 W2 W4 0 0 0 0 0
H1 H4 H8 H10 H20
H2 0
m1
s2 s4 s8 s10 s20 s40 0
m8 m10 m20 m40 0
m4 m2
AM / PM
s1
Start bit of real-time data 2 data access
Start bit of real-time data 1 data access
Day of the week data (00 to 06)
B7 B0
B7 B0
B7 B0
B7 B0
B7 B0
B7 B0
Figure 11 Real-Time Data Register
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
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Year dat a (00 to 99): Y1, Y2, Y4, Y8, Y10, Y20, Y40, Y80
Sets the lower two digits of the Western calendar year (00 to 99) and links together with the auto calendar
function until 2099.
Example: 205 3 (Y1, Y2, Y4, Y8, Y10, Y20, Y40, Y80) = (1, 1, 0, 0, 1, 0, 1, 0)
Month data (01 to 12): M1, M2, M4, M8, M10
Example: Dece mber (M1, M2, M4, M8, M10, 0, 0, 0) = (0, 1, 0, 0, 1, 0 ,0 ,0)
Day data (01 to 31): D1, D2, D4, D8, D10, D20
The count value is automatically change d by the auto calendar function.
1 to 31: Jan., Mar., May, July, Aug., Oct., Dec., 1 to 30: April, June, Sep., Nov.
1 to 29: Feb. (leap year), 1 to 28: Feb. (non-leap year)
Example: 29 (D1, D2, D4, D8, D10, D20, 0, 0) = (1, 0, 0, 1, 0, 1, 0, 0)
Day of the week data (00 to 06): W1, W2, W4
A septenary up counter . Day of the week is counted in the order of 00, 01, 02, …, 06, and 00. Set up day of the
week and the count value.
Hour data (00 to 23 or 00 to 11): H1, H2, H4, H8, H10, H20, AM / PM
In 12-hour mode, write 0; AM, 1; PM in the PM/AM bit . In 24-hour mode, users c an write either 0 or 1. 0 is
read when the hour data is from 00 to 11, and 1 is read when from 12 to 23.
Example (12-hour mod e): 11 p.m. (H1, H2, H4, H8, H10, H20, PM/AM , 0) = (1, 0, 0, 0, 1, 0, 1, 0)
Example (24-hour mod e): 22 (H1, H2, H4, H8, H10, H20, PM/AM , 0) = (0, 1, 0, 0, 0, 1, 1, 0)
Minute data (00 to 59): m1, m2, m4, m8, m10, m20, m40
Example: 32 minutes (m1, m2, m4, m8, m10, m20, m40, 0) = (0, 1, 0, 0, 1, 1, 0, 0)
Example: 55 minutes (m1, m2, m4, m8, m10, m20, m40, 0) = (1, 0, 1, 0, 1, 0, 1, 0)
Second data (00 to 59): s1, s2, s4, s8, s10, s20, s40
Example: 19 seconds (s1, s2, s4, s8, s10, s20, s40, 0) = (1, 0, 0, 1, 1, 0, 0, 0)
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 13
2. Status register 1
Status register 1 is a 1-by te reg ister tha t i s u sed to display and se t various modes. The bit con f igu ration i s shown below.
B7
RESET 12 / 24
R
R
R
R / W R / W
SC1
B6 B5 B4 B3 B2 B1 B0
BLD INT2 POC INT1
SC0
R
R / W
W
R: Read
W: Write
R / W: Read / write
Figure 12 Status Register 1
B0: POC
This flag is used to confirm whether the po wer is on. The po wer-on detect ion circu it oper ates at po wer-on and B0 is
set to "1". This flag is read-only. Once it is read, it is automatically set to "0". When this flag is "1", be sure to initialize.
Regarding the operation after power-on, refer t o " Power-on Detection Circuit and Register Status".
B1: BLD
This flag is set to "1" when the power supply voltage decreases to the level of detection voltage (VDET) or less. Users
can detect a drop in th e power supply vo ltage. Once this fla g is set to "1", it is not set to "0" again even i f the po wer
supply increases to the level of detection voltage (VDET) or more. T his f lag is read-only. When this flag is "1", be sure
to initialize. Regarding the operation of the power supply voltage detection circuit, refer to " Low Power Supply
Voltage Detection Circuit".
B2: INT2, B3: INT1
This flag indicat es the time se t by alarm and when the tim e has reach ed it. T his flag is set t o "1" when th e time that
users set by using th e alarm i nterrupt funct ion has c ome. The I NT1 f lag at alarm 1 interr upt mode and th e INT 2 flag
at alarm 2 interrupt mode are set to "1". Set "0" in INT1AE (B5 in the status register 2) or in INT2AE (B1 in the status
register 2) after reading "1" in the INT1 flag or in the INT2 flag. This flag is read-only. Once this flag is read, it is set to
"0" automatical ly.
B4: SC1, B5: SC0
These flags are SRAM type registers, they are 2 bits as a whole, can be freel y set by users.
B6: 24 / 12
This flag is used to set 12-hour or 24-hour mode. Set the flag ahead of write operation of the real-time data register in
case of 24-hour mode.
0: 12-hour mode
1: 24-hour mode
B7: RESET
The internal IC is initialized by setting this bit to "1". This bit is write-only. It is always "0" when reading. When
applying the power supply voltage to the IC, be sure to write "1" to this bit to initialize the circuit. Regarding each
status of data after initialization, refer to " Register Status After Initialization".
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
14
3. Status register 2
Status register 2 is a 1-by te register that is u sed to display and set various mode s. The bi t con figuration is show n be low.
B7
INT1FE INT1ME
R / W R / W
32kE
B6 B5 B4 B3 B2 B1 B0
INT2MEINT2FE
INT1AE
R / W R / W R / W R / W R / W R / W
INT2AE TEST
R / W: Read / write
Figure 13 Status Register 2
B0: TEST
This is a test flag for SII. Be sure to set this flag to "0" in use. If this flag is set to "1", be sure to initialize to set "0".
B1: INT2AE, B2: INT2ME, B3: INT2FE
These bits are used to select the output mode for the 2INT pin. Table 11 shows how to select the mode. To use an
alarm 2 interrupt, set alarm interrupt mode, then access the INT2 regist er.
Table 11 Output Modes for 2INT Pin
INT2AE INT2ME INT2FE 2INT Pin Output Mode
0 0 0 No interrupt
−*1 0 1 Output of user-set frequency
−*1 1 0 Per-minute edge interrupt
−*1 1 1 Minute-periodical interrupt 1 (50% duty)
1 0 0 Alarm 2 interrupt
*1. Don't care (both of 0 and 1 are acceptable).
B4: 32kE, B5: INT1AE, B6: INT1ME, B7: INT1FE
These bits are used to select the output mode for the 1INT pin. Table 12 shows how to select the mode. To use
alarm 1 interrupt, access the I NT1 register after setting the alarm interrupt mode.
Table 12 Output Modes for 1INT Pin
32kE INT1AE INT1ME INT1FE 1INT Pin Output Mode
0 0 0 0 No interrupt
0 −*1 0 1 Output of user-set fr equency
0 −*1 1 0 Per-minute ed ge interrupt
0 0 1 1 Minute-periodical interrupt 1 (50% duty)
0 1 0 0 Alarm 1 interrupt
0 1 1 1 Minute-periodical interrupt 2
1 −*1 −*1 −*1 32.768 kHz output
*1. Don't care (both of 0 and 1 are acceptable).
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 15
4. INT1 register and INT2 register
The INT1 and INT2 registers are to set up the output of user-set frequency, or to set up alarm interrupt. Users are able to
switch the output mode by using the status register 2. If selecting to use the output mode for alarm interrupt by status
register 2; these registers work as alarm-time data registers. If selecting the output of user-set frequency by status
register 2; these registers work as data registers to set the frequency for clock output. From each INT1 and INT2 pin,
a clock pulse and alarm interrupt are output.
4. 1 Alarm interrupt
Users can set the alarm time (the data of day of the week, hour, minute) by using the INT1 and INT2 registers which
are 3-byte data registers. The configuration of register is as well as the data register of day of the week, hour, minute,
in the real-time data register; is expressed b y the BCD code. Do not set a none xistent day. Users are necessary to
set up the alarm-time data according to the 12 / 24 hour mode that they set by using the status register 1.
H8H4 H2
H1
A1mE
m8
m4
m2
m1
H20
H10
m10 m20 m40
H8
H4
H2
H1
A2mE
m8
m4m2
m1
H20
H10
m10 m20 m40
AM /
PM
A1WE
0
0
W4
W2 W1
B7 B0
0 0
INT1 register
0
0
W4
W2
W1 0
INT2 register
A2WE
A1HE A2HE
AM /
PM
B7 B0
B7 B0
B7 B0
B7 B0
B7 B0
0
Figure 14 INT1 Register and INT2 Register (Alarm-Time Data)
The INT1 register has A1WE, A1HE, A1mE at B0 in each byte. It is possible to make data vali d; the data of day of
the week, hour, minute which are in the corresponded byte; by setting these bits to "1". This is as well in A2WE,
A2HE, A2mE in the INT2 register.
Setting example: alarm time "7:00 pm" in the INT1 register
(1) 12-hour mode (status register 1 B6 = 0)
Set up 7:00 PM
Data written to INT1 register
Day of the week −*1 −*1 −*1 −*1 −*1 −*1 −*1 0
Hour 1 1 1 0 0 0 1 1
Minute 0 0 0 0 0 0 0 1
B7 B0
*1. Don't care (both of 0 and 1 are acceptable).
(2) 24-hour mode (status register 1 B6 = 1)
Set up 19:00 PM
Data written to INT1 register
Day of the week −*1 −*1 −*1 −*1 −*1 −*1 −*1 0
Hour 1 0 0 1 1 0
1*2 1
Minute 0 0 0 0 0 0 0 1
B7 B0
*1. Don't care (both of 0 and 1 are acceptable).
*2. Set up the PM/AM flag along with the time setting.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
16
4. 2 Output of user-set frequency
The INT1 and INT2 registers are 1-byte data registers to set up the output frequency. Setting each bit B7 to B3 in the
register to "1", the frequency which corresponds to the bit is output in the AND-form. SC2 to SC4 in the INT1 register ,
and SC5 to SC7 in the INT2 register are 3-bit SRAM type registers that can be freely set by users.
B7
R / W R / W
8 Hz
B6 B5 B4 B3 B2 B1 B0
SC2 16 Hz
4 Hz
R / W R / W R / W R / W R / W R / W
SC3 SC4
2 Hz 1 Hz
R / W: Read / write
Figure 15 INT1 Register (Data Register for Output Frequency)
B7
R / W R / W
8 Hz
B6 B5 B4 B3 B2 B1 B0
SC5 16 Hz
4 Hz
R / W R / W R / W R / W R / W R / W
SC6 SC7
2 Hz 1 Hz
R / W: Read / write
Figure 16 INT2 Register (Data Register for Output Frequency)
Example: B7 to B3 = 50h
16 Hz
8 Hz
4 Hz
2 Hz
1 Hz
INT1 pin /
INT2 pin output
Status register 2
•
Set to INT1FE or INT2FE = 1
Figure 17 Example of Output from INT1 and INT2 Registers (Data Register for Output Frequency)
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 17
1 Hz clock output is synchronized with second-counter of the S-35390A.
INT1
pin /
INT2
pin
output (1 Hz)
Second-counter n + 1 n + 2
n
Figure 18 1 Hz Clock Output and Second-counter
5. Clock correction register
The clock correction register is a 1-byte register that is used to correct advance / delay of the clock. When not using this
function, set this register to "00h". Regarding the register values, refer to " Function of Clock Correction".
B7
R / W R / W
V3
B6 B5 B4 B3 B2 B1 B0
V5 V4
V2
R / W R / W R / W R / W R / W R / W
V6 V7
V1 V0
R / W: Read / write
Figure 19 Clock Correction Register
6. Free register
This free register is a 1-byte SRAM type register that can be set freely by users.
B7
R / W R / W
F3
B6 B5 B4 B3 B2 B1 B0
F5 F4
F2
R / W R / W R / W R / W R / W R / W
F6 F7
F1 F0
R / W: Read / write
Figure 20 Free Register
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
18
Power-on Detection Circuit and Register Status
The power-on detecti on circuit operates by power-on the S-35390A , as a result each register is cleared; each regist er is
set as follows.
Real-time data register: 00 (Y), 01 (M), 01 (D), 0 (day of the week), 00 (H), 00 (M), 00 (S)
Status register 1: "01h"
Status register 2: "80h"
INT1 register: "80 h"
INT2 register: "00 h"
Clock correction register: "00h"
Free register: "00h"
"1" is set in the POC flag (B0 in the status register 1) to indicate that power has been applied. To correct the oscillation
frequency, th e status register 2 go es in th e mode t he out p ut of user-set fr equency, so that 1 Hz clock pulse is outp ut fr om
the 1INT pin. When "1" is set in t he POC flag, be sure to init ialize. T he POC flag is set to "0" due to init ialization so t hat
the output of user-set frequency mode is cleared (Refer to " Register Status After Initialization").
For the regular operatio n of power-on detection circuit, as seen in Figure 21, t he period t o po wer-up the S-35390A is that
the voltage reaches 1.3 V within 10 ms after setting the IC’s power supply voltage at 0 V. When the po wer-on detecti on
circuit is not working normally is; the POC flag (B0 in the status register) is not in "1", or 1 Hz is not out put f rom the 1INT
pin. In this case, power-on the S-35390A once again because the internal data may be in the indefinite status.
Moreover, regarding the processing right after power-on, refer to " Flowchart of Initialization and Example of
Real-time Data Set-up".
Within 10 ms
1.3 V
0 V
*1
*1. 0 V indicates that there are no potential differences between the VDD
pin and VSS pin of S-35390A.
Figure 21 How to Raise the Power Supply Voltage
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 19
Register Status After Initialization
The status of each register after initialization is as follows.
Real-time data register: 00 (Y), 01 (M), 01 (D), 0 (da y of the week), 00 (H), 00 (M), 00 (S)
Status register 1: "0 B6 B5 B4 0 0 0 0 b"
(In B6, B5, B4, the data of B6, B5, B6 in the status register 1 at initializat ion is set.
Refer to Figure 22.)
Status register 2: "00h"
INT1 register: "00h"
INT2 register: "00h"
Clock correction register: "00h"
Free register: "00h"
18
9 1
0 0 0 1 1 0
START
SCL
SDA
Device code +
command
STOP
0 0
B7 B5
0 0 0 0
0
0
1 1
18
9 1
0 0 0 1 1 0
START
STOP
0 1
B7 B5 : Not reset
L L L L
L
L L H
0 0
Write to status register 1 Read from status register 1
ACK
ACK
ACK
NO_ACK
: Output from S-35390A
: Input from the master device
R / W R / W
Device code +
command
Write "1" to reset flag and SC0.
Figure 22 Data of Status Register 1 at Initialization
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
20
Low Power Supply Voltage Detection Circuit
The S-35390A has a low power supply voltage detection circuit, so that users can monitor drops in the power supply
voltage by reading the BLD flag (B1 in the status register 1). There is a hysteresis width of approx. 0. 15 V typ. between
detection voltage and release voltage (refer to " Characteristics (Typical Data)"). The low power supply voltage
detection circuit does the sampling operation only once in one sec for 15.6 ms.
If the power supply voltage decreases to the level of detection voltage (VDET) or less, "1" is set to the BLD flag so that
sampling operation stops. Once "1" is detected in the BLD flag, no sampling operation is performed even if the power
supply voltage increases to the level of release voltage or more, and "1" is hel d in the BLD flag.
Furthermore, the S-35390A does not initialize the internal circuit even if "1" is set to the BLD flag. If the BLD flag is "1"
even after the power supply voltage is recovered, the internal circuit may be in the indefinite status. In this case, be sure to
initialize the circuit. Without initializing, if the next BLD flag reading is done after sampling, the BLD flag gets reset to "0". In
this case, be sure to initialize although the BLD flag is in "0" because the internal circuit may be in the indefinite status.
V
DD
BLD flag
Stop Stop Stop
Sampling pulse
Hysteresis widt h
0.15 V approximately
BLD flag reading
Detection voltage Release
voltage
15.6 ms
1 s 1 s
Time keeping power
supply voltage (min.)
Figure 23 Timing of Low Power Supply Voltage Detection Circuit
Circuits Power-on and Low Power Suppl y Voltage Detection
Figure 24 shows the changes of the POC flag and BLD flag due to VDD fluctuation.
VDD
BLD flag
Status register 1
readin
g
POC flag
VSS
Low power supply voltage
detection voltage Low power supply voltage
detecti on voltage
Figure 24 POC Flag and BLD Flag
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 21
Correction of Nonexistent Data and End-of-Month
When users write the real-time data, the S-35390A checks it. In case that the data is invalid, the S-35390A does the
following procedures.
1. Processing of nonexistent data
Table 13 Processing of Nonexistent Data
Register Normal Data Nonexistent Data Result
Year data 00 to 99 XA to XF, AX to FX 00
Month data 01 to 12 00, 13 to 19, XA to XF 01
Day data 01 to 31 00, 32 to 39, XA to XF 01
Day of the week data 0 to 6 7 0
24-hour 0 to 23 24 to 29, 3X, XA t o XF 00
Hour data*1 12-hour 0 to 11 12 t o 20, XA to XF 00
Minute data 00 to 59 60 to 79, XA to XF 00
Second data*2 00 to 59 60 to 79, XA to XF 00
*1. In 12-hour mode, write the PM/AM flag (B1 in hour data in the real-time data register).
In 24-hour mode, the PM/AM flag in the real-time data register is omitt ed. Ho wever in the fl ag of readin g, users are
able to read 0; 0 to 11, 1; 12 to 23.
*2. Processi ng of non e xistent data, regar ding se cond data, is d one b y a carry pulse which is generated in 1 second, after
writing. At this point the carry pulse is sent to the minute-counter.
2. Correction of end-of-month
A none xistent day, such as February 30 and April 31, is set to the first day of the next month.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
22
1INT Pin and 2INT Pin Output Mode
These are selectable for the output mode for 1INT and 2INT pins;
Alarm interrupt, the out put of user-set fr equ enc y, per-minute edge interrupt output , minut e-peri odi cal int errupt out p ut 1. I n
the 1INT pin output mode, in addition to the above modes, minute-periodical interrupt output 2 and 32.768 kHz output
are also selectable.
To switch the output mode, use the status register 2. Refer to "3. Status register 2" in " Configuration of Regis ters ".
When switching the output mode, be careful of the output status of the pin. Especially, when using alarm interrupt / output
of frequency, switch the output mode after setting "00h" in the INT1 / INT2 register. In 32.768 kHz output / per-minute edge
interrupt output / minute-periodical interrupt out put, it is unnecessary to set data in the INT1 / INT2 register for users.
Refer to the followings regarding each operation of output modes.
1. Alarm interrupt output
Alarm interrupt output is the function to output "L" from the 1INT / 2INT pin, at the alarm time which is set by user has
come. If setting the pin output to "H", turn off the alarm function by setting "0" in INT1AE / INT2AE in the status register 2.
To set the alarm time, set the data of day of the week, hour and minut e in the INT1 / INT2 register. Refer to "4. INT1
register and INT2 register" in " Configuration of Registers".
1. 1 Alarm setting of "W (day of the week), H (hour), m (minute)"
OFF
*1
INT1AE / INT2AE
mx
Comparator
Hx Wx
INTx register alarm enable flag
• AxHE = AxmE = AxWE = "1"
Status register 2 setting
• INT1 pin output mode
32kE = 0, INT1ME = INT1FE = 0
• INT2 pin output mode
INT2ME = INT2FE = 0 INT1 register
INT2 register
Alarm interrupt
Second
Minute Year
Day of
the week
Day Month
Real-time data
W (day of the week)
01 s 59 s
INT1 pin / INT2 pin
Change by program
Alarm time matches
Period when alarm time matches
Change by program
H h 00 m 00 s
H h (m − 1) m 59 s H h (m + 1) m 00 s
Change by program
Real-time data
Hour
*1. If users clear INT1AE / INT2AE once; "L" is not output from the 1INT / 2INT pin by setting INT1AE / IN T2AE e nable
again, within a period when the alarm time matches real-time data.
Figure 25 Alarm Interrupt Output Timing
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 23
1. 2 Alarm setting of "H (hour)"
mx
Comparator
Hx Wx Dx Mx Yx
OFF OFF
*1 *1
INT1AE / INT2AE
INT1 pin / INT2 pin
Alarm interrupt
Second
Real-time data
Minute
INT1 register
INT2 register
YearHour
Day of
the week
Day Month
Change by program
Alarm time matches
Period when alarm time matches
Change by program
Real-time data
Alarm time
matches
*2
01 s 59 sH h 00 m 00 s H h 59 m 59 sH h 01 m 00 s (H + 1) h 00 m 00 s
(H - 1) h 59 m 59 s
Change by program Change by program
INTx register alarm enable flag
•
AxHE = AxmE = AxWE = "1"
Status register 2 setting
•
INT1 pin output mode
32kE = 0, INT1ME = INT1FE = 0
•
INT2 pin output mode
INT2ME = INT2FE = 0
*1. If users clear INT1AE / INT2AE once; "L" is not output from the 1INT / 2INT pin by setting INT1AE / INT2AE enable
again, within a period when the alarm time matches real-time data.
*2. If turning the alarm output o n by changing the program, within the period when the alarm time mat c hes real-time data,
"L" is output again f rom the 1INT / 2INT pin when the minute is counted up.
Figure 26 Alarm Interrupt Output Timing
2. Output of user-set frequency
The output of user-set f requenc y is the function t o output t he frequenc y which is selected by using data, from the 1INT
/ 2INT pin, in the AND-form. Set up the data of frequency in the INT1 / INT2 register.
Refer to "4. INT1 register and INT2 register" in " Configuration of Registers".
OFF
INT1FE / INT2FE
INT1 pin / INT2 pin
Change by program
Free-run output starts
Status register 2 setting
• INT1 pin output mode
32kE = 0, INT1AE = Don’t care (0 or 1), INT1ME = 0
• INT2 pin output mode
INT2AE = Don’t care (0 or 1), INT2ME = 0
Figure 27 Output Timing of User-set Frequency
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
24
3. Per-minute edge interrupt output
Per-minute edge interrupt output is the function to output "L" from the 1INT / 2INT pin, when the first minute-carry
processing is done, after selecting the output mode.
To set the pin output to "H", t urn off the output mode of per-minute edge int errupt. In the 1INT pin output mode, input
"0" in INT1ME in the status register 2. In the 2INT pin output mode, input "0" in I NT2ME.
OFF
INT1ME / INT2ME
INT1 pin / INT2 pin
"L" is output again if this period is within 7.81 ms
*1
.
Change by program
Minute-carry processing Minute-carry
processing
Status register 2 setting
• INT1 pin output mode
32kE = 0, INT1AE = Don’t care (0 or 1), INT1FE = 0
• INT2 pin output mode
INT2AE = Don’t care (0 or 1), INT2FE = 0
*1. Pin output is set to "H" by disabling the output mode within 7.81 ms, because the signal of this procedure is
maintained for 7.81 ms. Note that pin output is set to "L" by setting enable the output mode again.
Figure 28 Timing of Per-Minute Edge Interrupt Output
4. Minute-periodical interrupt output 1
The minute-periodical interrupt 1 is the function to output the one-minute clock pulse (Duty 50%) from the 1INT / 2INT
pin, when the first minute-carry processing is done, after selecting the output mode.
INT1ME, INT1FE
INT2ME, INT2FE
30 s 30 s 30 s 30 s 30 s 30 s 30 s 30 s 30 s
INT1 pin / INT2 pin
Minute-carry
processing Minute-carry
processing
Minute-carry
processing Minute-carry
processing Minute-carry
processing
"L" is output again if this period is within 7.81 ms
*1
.
Change by program (OFF)
"H" is output again if this period is within 7.81 ms
"L" is output at the next minute-carry processing
Status register 2 setting
• INT1 pin output mode
32kE = 0, INT1AE = 0
• INT2 pin output mode
INT2AE = 0
*1. Setting the output mode disable makes the pin output "H", while the output f rom the 1INT / 2INT pin is in "L".
Note that pin o utput is set to "L" by setting e nable the output mode again.
Figure 29 Timing of Per-Minute Steady Interrupt Output 1
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 25
5. Minute-periodical interrupt output 2 (only in the 1INT pin output mode)
The output of minute-periodi cal interrupt 2 is the function to output "L", for 7.81 ms, from the 1INT pin, synchronizing
with the first minute-carry processing after selecting the output mode. However, during reading in the real-time data
register, the pr ocedure dela ys at 0.5 seconds max. thus ou tput "L" from the 1INT pin also dela ys at 0.5 seconds max.
During writing in the real-time data register, some delay is made in the output period due to write timing and the
second-data during writing.
(1) During normal operation
7.81 ms 7.81 ms 7.81 ms
60 s 60 s
INT1 pin
Minute-carry processing Minute-carry processing Minute-carry processing
(2) During reading in the real-time data register
7.81 ms 7.81 ms 7.81 ms
INT1 pin
Serial
communication
0.5 s max.
60 s 60 s
Real-time data
read command Real-time
data reading
Real-time data
read command Real-time
data reading
Minute-carry processing Minute-carry processing Minute-carry processing
(Normal minute-
carry processing)
(3) During writing in the real-time data register
7.81 ms 7.81 ms 7.81 ms
INT1 pin
Real-time data
write timing
55 s 80 s
Minute-carry processing Minute-carry processing Minute-carry processing
45 s 10 s 30 s 50 s
The output period is shorter. The output period is longer.
Second data of writing: "50" s Second data of writing: "10" s
Figure 30 Timing of Minute-periodical Interrupt Output 2
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
26
6. Operation of power-on detection circuit (only in the 1INT pin output mode)
When power is applied to the S-35390A, the power-on detection operates to set "1" in the POC flag (B0 in the status
register 1). A 1 Hz clock pulse is output from the 1INT pin.
OFF
INT1FE
• 32kE = 0, INT1AE = INT1ME = 0
Status register 2 setting
INT1 pin
0.5 s
0.5 s
Change by reset command
Figure 31 Output Timing of 1INT Pin during Operation of Power-on Detection Circuit
Function of Clock Correction
The function of clock correction is t o correct advance / delay of the clock due to the deviation of oscillat ion frequency, in
order to make a high precise clock. For correction, the S-35390A adjusts the clock pulse by using a certain part of the
dividing circuit, not adj ust in g the f r equency of the cr ystal os cillator. Correction is performed once every 2 0 seconds (or 6 0
seconds). The minimum resolution is approx. 3 ppm (or approx. 1 ppm) and the S-35390A corrects in the range of −195.3
ppm to +192.2 ppm (or of −65.1 ppm to +64.1 ppm). (Ref er to Table 14.) Users can set up this function by using the clock
correction register. Regarding how to calculate the setting data, refer to "1. How to calculate". When not using this
function, be sure to set "00h".
Table 14 Function of Clock Correction
Item B0 = 0 B0 = 1
Correction Every 20 seconds Every 60 seconds
Minimum resolution 3.052 ppm 1.017 ppm
Correction range −195.3 ppm to +192.2 ppm −65.1 ppm to +64.1 ppm
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 27
1. How to calculate
1. 1 If current oscillation frequency > target frequency (in case the clock is fast)
Correction value
*1
= 128 − Integral value (Current oscillation frequency
actual measurement value
*2
) (Minimum resolution
*4
)
(Current oscilla t ion frequency
actual measurement value
*2
) (Target oscillati on frequency
*3
)
−
×
Caution The figure range which can be corrected is that the calculated value is from 0 to 64.
*1. Convert this value to be set in the clock correction register. For how to convert, refer to "(1) Calculation
example 1".
*2. Measurement value when 1 Hz clock pulse is output from the 1INT pin (or 2INT pin).
*3. Target value of average frequency when the clock correction function is used.
*4. Refer to "Table 14 Function of Clock Correction".
(1) Calculation example 1
In case of current oscillation frequency actual measurement value = 1.000070 [Hz], ta rget oscillation frequency =
1.000000 [Hz], B0 = 0 (Minimum resolution = 3.052 ppm)
Correction value = 128 − Integral value ⎝
⎛⎠
⎞
()
1.000070 − ()
1.000000
()
1.000070 × ()
3.052 × 10−6
= 128
− Integral value (22.93) = 128 − 22 = 106
Convert the correction value "106" to 7-bit binary and obtain "1101010b".
Reverse the correction value "1101010b" and set it to B7 to B1 of the clock correction register.
Thus, set the clock correction regist er:
(B7, B6, B5, B4, B3, B2, B1, B0) = (0, 1, 0, 1, 0, 1, 1, 0)
1. 2 If current oscillation frequency < target frequency (in case the clock is slow)
Correction value = Integral val ue (Current oscillation frequency
actual measurement value) (Minimum resolution)
(Current oscillation frequency
actual measurement value)
(Target oscillation frequency) −
×
+ 1
Caution The figure range which can be corrected is that th e calculated value is from 0 to 62.
(1) Calculation example 2
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], ta rget oscillation frequency =
1.000000 [Hz]. B0 = 0 (Minimum resolution = 3.052 ppm)
Correction value = Integral value ⎝
⎛⎠
⎞
()
1.000000 − ()
0.999920
()
0.999920 × ()
3.052 × 10-6 + 1
= Integral value (26.21) + 1 = 26 + 1 = 27
Thus, set the clock correction regist er:
(B7, B6, B5, B4, B3, B2, B1, B0) = (1, 1, 0, 1, 1, 0, 0, 0)
(2) Calculation example 3
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], ta rget oscillation frequency =
1.000000 [Hz], B0 = 1 (Minimum resolution = 1.017 ppm)
Correction value = Integral value ⎝
⎛⎠
⎞
()
1.000000 − ()
0.999920
()
0.999920 × ()
1.017 × 10-6 + 1
= Integral value (78.66) + 1
This calculated value exceeds the correctable range 0 to 62.
B0 = "1" (minimum resolution = 1.017 ppm) indicates the correction is impossible.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
28
2. Setting values for reg i sters and correction values
Table 15 Setting Values for Registers and Correction Values (Minimum Resolution: 3.052 ppm (B0 = 0))
B7 B6 B5 B4 B3 B2 B1 B0 Correction Value
[ppm] Rate
[s / day]
1 1 1 1 1 1 0 0 192.3 16.61
0 1 1 1 1 1 0 0 189.2 16.35
1 0 1 1 1 1 0 0 186.2 16.09
•
•
• •
•
•
•
•
•
0 1 0 0 0 0 0 0 6.1 0.53
1 0 0 0 0 0 0 0 3.1 0.26
0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 0 −3.1 −0.26
0 1 1 1 1 1 1 0 −6.1 −0.53
1 0 1 1 1 1 1 0 −9.2 −0.79
•
•
• •
•
•
•
•
•
0 1 0 0 0 0 1 0 −189.2 −16.35
1 0 0 0 0 0 1 0 −192.3 −16.61
0 0 0 0 0 0 1 0 −195.3 −16.88
Table 16 Setting Values for Registers and Correctio n Values (Minimum Resolution: 1.017 ppm (B0 = 1))
B7 B6 B5 B4 B3 B2 B1 B0 Correction Value
[ppm] Rate
[s / day]
1 1 1 1 1 1 0 1 64.1 5.54
0 1 1 1 1 1 0 1 63.1 5.45
1 0 1 1 1 1 0 1 62.0 5.36
•
•
• •
•
•
•
•
•
0 1 0 0 0 0 0 1 2.0 0.18
1 0 0 0 0 0 0 1 1.0 0.09
0 0 0 0 0 0 0 1 0 0
1 1 1 1 1 1 1 1 −1.0 −0.09
0 1 1 1 1 1 1 1 −2.0 −0.18
1 0 1 1 1 1 1 1 −3.0 −0.26
•
•
• •
•
•
•
•
•
0 1 0 0 0 0 1 1 −63.1 −5.45
1 0 0 0 0 0 1 1 −64.1 −5.54
0 0 0 0 0 0 1 1 −65.1 −5.62
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 29
3. How to confirm setting value for register an d result of correction
The S-35390A does not adjust the frequency of the crystal oscillatio n by using the clock correction func tion. Therefore
users cannot confirm if it is corrected or not by measuring output 32. 768 kHz. When the function to clock correction is
being used, the c ycle of 1 Hz clock pulse output f rom the 1INT pin changes once in 20 times or 60 t imes, as shown in
Figure 32.
INT1 pin
(1 Hz output)
a a a a
b
In case of B0 = 0: a = 19 times, b = Once
In case of B0 = 1: a = 59 times, b = Once
19 times or 59 times Once
Figure 32 Confirmation of Correction Result
Measure a and b by using t he fr equency co unt er*1. Calculat e the average f requenc y (Tave) based on the measuremen t
results.
B0 = 0, Tave = (a × 19 + b) ÷ 20
B0 = 1, Tave = (a × 59 + b) ÷ 60
Calculate the error of the clock based on the average frequency (Tave). The following shows an example for
confirmation.
Confirmation exam ple: When B0 = 0, 66h is set
Measurement results: a = 1.000080 Hz, b = 0.998493 Hz
Clock Correction Register Setting Value Average Frequency [Hz] Per Day [s]
Before correction 00 h (Tave = a) 1.000080 86393
After correction 66 h (Tave = (a × 19 + b) ÷ 20) 1.00000065 86399.9
Calculating the average frequency allows to confirm the result of correction.
*1. Use a frequency counter with 7-digit or greater precision.
Caution Measure the oscillation frequency under the usage conditions.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
30
Serial Interface
The S-35390A transmits / receives various commands via I2C-bus serial interface to read / write data. Regarding
transmission is as follows.
1. Start condition
A start conditio n is when the SDA line ch anges "H" to "L" when the SCL line is in "H", so that the access starts.
2. Stop condition
A stop condition is when the SDA line changes "L" to "H" when the SCL line is in "H", and the access stops, so that the
S-35390A gets standby.
t
SU.STA
t
HD.STA
t
SU.STO
Start condition Stop condition
SCL
SDA
Figure 33 Start / Stop Conditions
3. Data transfer and acknowledgment signal
Data transmission is performed for every 1-byte, after detecting a start condition. T ransmit data w hile the SCL line is in
"L", and be careful of spec of tSU.DAT and tHD. DAT when changing the SDA li ne. If the SDA line c hanges while the SCL
line is in "H", the data will be recognized as start/stop condition in spite of data transmission. Note that by this case, the
access will be interrupted.
During data transmission, every moment receiving 1-byte data, the devices which work for receiving data send an
acknowledgment signal back. F or example, a s seen in Figure 34, in case that the S-3539 0A is the device working for
receiving data and the master device is t he one working for sending data; when the 8th clock pulse fall s, the master
device releases the SDA line. After that, the S-35390A sends an acknowledgment signal back, and set the SDA line to
"L" at the 9th clock pulse. The S-35390A does not output an acknowledgment signal is that the access is not being
done regularl y.
1 89
Output acknowledgment
("L" active)
t
PD
Start condition
SCL
(Input from
S-35390A)
SDA
(Output from the
master device)
SDA
(Input from
S-35390A)
SDA is released
t
SU.DAT
t
HD.DAT
High-Z
High-Z
Figure 34 Output Timing of Acknowledgment Signal
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 31
The followings are data reading / writing in the S-35390A.
3. 1 Data reading in the S-35390A
After detecting a start condition, the S-35390A receives device code and command. The S-35390A enters the
read-data mode by the read / write bit "1". The data is output from B7 in 1- byte. Input an acknowledgment signal
from the master device every moment that the S-35390A outputs 1-byte data. However, do not input an
acknowledgment signal (input NO_ACK) for the last data-byte output from the master device. This procedure
notifies the completion of reading. Next, input a stop condition to the S-35390A to finish access.
18
9 1
ACK
0 0 0 1 1 0
START
SCL
SDA
B7 B0
Device code + command
NO_ACK
STOP
: Output from S-35390A
: Input from the master device
0 1
R / W
Input NO_ACK after the 1st byte
of data has been output.
1-byte data
Figure 35 Example of Data Reading 1 (1-Byte Data Register)
36
9 1
ACK
1 0 1 1 0
START
SCL
SDA
B7 B0 B7 B0
NO_ACK
STOP
1
0
ACK
B0
B7
18 27
ACK
1
: Output from S-35390A
: Input f r om the master device
Input NO_ACK afte r the 3r d byte of data
has been output.
R / W
3-byte data
Device code + command
Figure 36 Example of Data Reading 2 (3-Byte Data Register)
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
32
3. 2 Data writing in the S-35390A
After detecting a start condition, the S-35390A receives device code and command. The S-35390A enters the
write-data mode by the read / write bit "0". Input data from B7 to B0 in 1-byte. The S-35390A outputs an
acknowledgment signal "L" every moment that 1-byte data is input. After receiving the acknowledgment signal
which is for the last byte-data, input a stop condition to the S-35390A to finish access.
18
9 1
ACK
0 0 0 1 1 0
START
SCL
SDA
B7 B0
ACK
STOP
: Output from S- 35390 A
: Input from the ma ster device
0 0
R / W
1-byte data
Device code + command
Figure 37 Example of Data Writing 1 (1-Byte Data Register)
18
9 1
ACK
1 0 0 1 1 0
START
SCL
SDA
B7 B0
ACK
STOP
: Output f r om S-35390A
: In
p
ut from t he master device
1 0
R / W
ACK
ACK
27 36
B7 B0 B7 B0
3-byte data
Device code + com mand
Figure 38 Example of Data Reading 2 (3-Byte Data Reg ister)
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 33
4. Data access
4. 1 Real-time data 1 access
72
9 1
ACK
1 0
1
1 0
START
SCL
SDA
Year data Second data
B7 B0 B7 B0
R / W
ACK
*1
STOP
0
0
ACK
*2
I/O mode switching I/O mode switching
ACK
*2
Device code +
command
18 63
*1. Set NO_ACK = 1 when reading.
*2. Transmit ACK = 0 fr om the master device to the S-35390A when reading.
Figure 39 Real-Time Data 1 Access
4. 2 Real-time data 2 access
36
9 1
ACK
1 0 1 1 0
START
SCL
SDA
Hour data Second data
B7 B0 B7 B0
R / W
ACK
*1
STOP
1
0
ACK
*2
I/O mode switching I/O mode switching
B0
B7
Minute data
18 27
ACK
*2
Device code +
command
*1. Set NO_ACK = 1 when reading.
*2. Transmit ACK = 0 from the master device to the S-35390A when reading.
Figure 40 Real-Time Data 2 Access
4. 3 Status register 1 access and status register 2 access
18
9
1
ACK
0 0 0 1 1 0
START
I/O mode switching
SCL
SDA
Status data
B7 B0
I/O mode switching
*1 R / W
ACK
*2
STOP
Device code +
command
*1. 0: Status register 1 selected, 1: Status register 2 selected
*2. Set NO_ACK = 1 when reading.
Figure 41 Status Register 1 Access and Status Register 2 Access
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
34
4. 4 INT1 register access and INT2 register access
In reading / writing the INT1 and INT2 registers, data varies depending on the setting of the status register 2. Be sure
to read / write after setting the status register 2. When setting the alarm by using the status register 2, these registers
work as 3-byte alarm time data registers, in other statuses, they work as 1-byte registers. When outputting the
user-set frequency, they are the data registers to set up the frequency.
Regarding details of each data, refer to "4. INT1 register and INT2 register" in " Configuration of R e gis te rs ".
Caution Users cannot use both functions of alarm 1 interrupt and output of user-set frequency for the
1INT pin and 2INT pin simultaneously.
36
9
1
ACK
0 1 0 1 1 0
START
SCL
SDA
Day of the week
data
Minute data
B7 B0 B7 B0
*1 R / W
ACK
*2
STOP
ACK
*3
ACK
*3
I/O mode switching I/O mode switching
27
18
Hour data
B7 B0
Device code +
command
*1. 0: INT1 register selected, 1: INT2 register selected
*2. Set NO_ACK = 1 when reading.
*3. Transmit ACK = 0 fr om the master device to the S-35390A when reading.
Figure 42 INT1 Register Access and INT2 Register Access
18
9
1
ACK
1 0 1 1 0
START
I/O mode switching
SCL
SDA
Frequency
setting data
B7 B0
I/O mode switching
R / W
ACK
*2
STOP
*1
0
Device code +
command
*1. 0: INT1 register selected, 1: INT2 register selected
*2. Set NO_ACK = 1 when reading.
Figure 43 INT1 Register and INT2 Register (Data Register for Output Frequency) Access
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 35
4. 5 Clock correctio n register access
18
9 1
ACK
1 1 0 1 1 0
START
I/O mode switching
SCL
SDA
Clock
correcti on data
B7 B0
R / W
ACK
*1
STOP
0
I/O mode switching
Device code +
command
*1. Set NO_ACK = 1 when reading.
Figure 44 Clock Correction Register Access
4. 6 Free register access
18
9 1
ACK
1 1 0 1 1 0
START
I/O mode switching
SCL
SDA
Free register
data
B7 B0
Device code +
command
R / W
ACK
*1
STOP
1
I/O mode switching
*1. Set NO_ACK = 1 when reading.
Figure 45 Free Register Access
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
36
Reset After Communication Interruption
In case of communication interruption in the S-35390A, for example, during communication the power supply voltage
drops so that only the master device is reset; the S-35390A does not operate the next procedure because the internal
circuit keeps the state prior to communicatio n interruption. T he S-35390A does not have a reset pi n so that users usua lly
reset its internal circuit by inputting a stop condition. However, if the SDA is outputting "L" (during output of
acknowledgment signal or reading), t he S-35390A does not accept a st op condition from the master device. I n this case,
users are necessary to finish acknowledgment output or reading of the SDA. Figure 46 shows how to reset.
First, input a start condition f rom t he master device (the S-3 5390A cannot detect a start condit ion beca use t he SDA in the
S-35390A is outputting "L"). Next, input a clock pulse equivalent to 7-byte data access (63-clock) from the SCL. During this,
release the SDA line for the master device. By this procedure, SDA I/O before communication interrupt ion is finished, so
that the SDA line in the S-35390A is released. After that, inputting a stop condition resets the internal circuit so that restore
the regular communication. T his reset procedure is recom mended to perf orm at initializa tion of the s ystem after rising the
master device’s power supply voltage.
1 2 62 63
8 9
Start
condition Stop
condition
Clocks equivalent to 7-byte d ata access
SCL
"L" "L" or High-Z High- Z
SDA
(Output from
the master
device
)
SDA
(Output from
S-35390A)
SDA "L" or High-Z
"L"
Figure 46 How to Reset
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 37
Flowchart of Initialization and Example of Real-time Data Set-up
Figure 47 is a recommended flowchart when the master device shifts to a normal operation status and initiates
communication with the S-35390A. Regarding how to apply power, refer to " Power-on Detection Circuit and Register
Status". It is unnec essary for users to comply with this flo wchart of real-time data strictly. And if using the defa ult data at
initializing, it is also unnecessary to set up again.
Confirm data in status
register 1
OK
Set real-time data 1
Read real-time data 1*2
Wait for 0.5 s*1
Read status re
g
ister 1
POC = 0 NO
YES
BLD = 0
YES
OK
END
Read status re
g
ister 1
Read status re
g
ister 1
NO
NO
YES
START
POC = 1
Set 24-hour / 12-hour mode
to status register 1
Initialize
(status register 1 B7 = 1)
BLD = 0
YES
Read real-time data 1
NG
Confirm data in real-time
data 1
NG
NO
*1. Do not communicate for 0.5 seconds since the power-on detect ion circuit is in operation.
*2. Reading the real-time data 1 should be completed within 1 second after setting the real-time data 1.
Figure 47 Example of Initialization Flowchart
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
38
Examples of Application Circuits
V
CC
XOUT
XIN
S-35390A SDA
VSS
VDD
SCL
VSS
VCC
CPU
INT1
System
power supply
C
g
10 kΩ
1 kΩ
INT2 10 kΩ
1 kΩ
Caution 1. Because the I/O pin has no protecti ve diode on the VDD si de, the relati on of VCC ≥ VDD is possible,
but pay careful attention to the specifications.
2. Start communication under stable condition after power-on the power supply in the system.
Figure 48 Application Circuit 1
VCC
CPU
S-35390A SDA
VSS
VDD
SCL
INT1
System power
supply
VSS
XOUT
XIN
10 kΩ
INT2 10 kΩ
1 kΩ
1 kΩ
C
g
Caution Start communication under stable condition after power-on the power supply in the system.
Figure 49 Application Circuit 2
Caution The above connection diagrams do not guarantee operation. Set the constants after performing
sufficient evaluation using the actual application.
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 39
Adjustment of Oscillation Frequency
1. Configuration of oscillator
Since crystal oscillation is sensitive to external noise (the clock accuracy is affected), the following measures are
essential for optimizing the oscillation configuration.
• Place the S-35390A, crystal oscillator, and external capacitor (Cg) as close to each other as possible.
• Increase the insulation resistance between pins and t he substrate wiring patterns of XIN and XOUT.
• Do not place any signal or power lines close to the oscillator.
• Locating the GND layer immediately below the oscillator is recommende d.
• Locate the bypass capacitor adjacent to the power supply pin of the S-35390A.
S-35390A
XOUT
XIN
Rf =
100 MΩ
Rd =
100 kΩ
Cd =
8 pF
Cg
Cd
Rd
Rf
Parasitic capacitance*3
Crystal oscillator: 32.768 kHz
Parasitic capacitance*3
CL = 6 pF*1
Cg = None*2 to 9.1 pF
Oscillator internal constant
standard values:
*1. When setting the value for the crystal oscillator’s CL as 7 pF, connect Cd externally if necessary.
*2. The oscillator operates even when Cg is not connected. Note that t he oscillation frequenc y is in the direction t hat it
advances.
*3. Design the b oard so that the parasitic capacitance is within 5 pF.
Figure 50 Connection Diagram 1
XIN
Crystal
oscillator XOUT
VSS
C
g
8
7
6
5
1
2
3
4
S-35390A
Locate the GND layer in the
layer immediately below
Figure 51 Connection Diagram 2
Caution 1. When using the crystal oscillator with a CL exceeding the rated value (7 pF) (e.g : CL = 12.5 pF),
oscillation operation may become unstable. Use a crystal oscillator with a CL value of 6 pF or 7 pF.
2. Oscillation characteristics is subject to the variation of each component such as substrate parasitic
capacitance, parasitic resistance, crystal oscillator, and Cg. When configuring an oscillator, pay
sufficient attention for them.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
40
2. Measurement of oscillation frequency
When the S-35390A is turned on, the internal po wer-on detec tor operat es and a signal of 1 Hz is output f rom the 1INT
pin to select the cryst al oscillator and optimize the Cg value. Turn the power on and measure the signal with a frequency
counter follo wing the circuit configuration shown in Figure 52.
If 1 Hz signal is not output, the power-on detector does not operate normally. Turn of f the power and then turn it on again.
For how to apply power, refer to " Power-on Detecti on Circuit and Register Status".
Remark If the error range is ±1 ppm in relation to 1 Hz, the time is shifted by approximately 2.6 seconds per month
(calculated using the following mode).
10–6 (1 ppm) × 60 seconds × 60 minutes × 24 hours × 30 days = 2.592 seconds
INT1
INT2
SDA
SCL S-35390A
VDD
XOUT
XIN
VSS
C
g
1 kΩ
10 kΩ
1 kΩ
Frequency
counter
Open
or pull-up
Figure 52 Configuration of Oscillation Frequency Measurement Circuit
Caution 1. Use a high-accuracy frequency counter of 7 digits or more.
2. Measure the oscillation frequency under the usage conditions.
3. Since the 1 Hz signal continues to be output, initialization must be executed during normal
operation.
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 41
3. Adjustment of oscillation frequency
3. 1 Adjustment by setting Cg
Matching of the crystal oscillator with the nominal frequency must be performed with the parasitic capacitance on the
board included . Select a crystal oscillator and optimize the Cg value in accordance with the flowchart below.
START
END
YES
NO
YES
NO
NO
YES
NO
YES
Set to center
of variable
capacitance*3
Select a crystal
oscillator*1
Variable
capacitance
Change Cg
Optimal
value*2
Frequency
Cg in
specification
Set Cg
Make fine adjustment
of frequency using
variable capacitance
Trimmer capacitor
Fixed capacitor
*1. Request a crystal manufacturer for matching evaluation between the IC and a crystal. The recommended crystal
characteristic values are, CL value (load capacitance) = 6 pF, R1 value (equivalent serial resistance) = 50 kΩ
max.
*2. The Cg value must be selected on the actual PCB since it is affected by parasitic capacitance. Select the
external Cg value in a range of 0 pF to 9. 1 pF.
*3. Adjust the rotation angle of the variable capacitance so that the capacitance value is slightly smaller than the
center, and confirm the oscillation frequency and the center value of the variable capacitance. This is done in
order to make the capacitance of the center value smaller than one half of the actual capacitance value because
a smaller capacitance value increases the frequency variation.
Figure 53 Crystal Oscillator Setting Flow
Caution 1. The oscillation frequency varies depending on the ambient temperature and power supply
voltage. Refer to " Characteristics (Typical Data)".
2. The 32.768 kHz crystal oscillator operates more slowly at an operating temperature than
higher or lower +20°C to +25°C. Therefore, it is recommended to set the oscillator to operate
slightly faster at normal temperature.
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
42
Precautions
• Although the IC contains a static electricity protection circuit, static electricity or voltage that exceeds the limit of the
protection circuit should not be applied.
• Seiko Instruments Inc. assumes no responsibility for the way in which this IC is used in products created using this IC or
for the specific ations of that p roduct, nor doe s Seiko Instruments Inc. assume a ny respo nsibilit y for an y infring ement o f
patents or copyrights by products that include this IC either in Japan or in other countries.
2-WIRE REAL-TIME CLOCK
Rev.4.0_00 S-35390A
Seiko Instruments In c. 43
Characteristics (Typical Data)
1. Standby current v s. VDD characteristics 2. Current consumption when 32 kHz is output
vs. VDD characteristics
Ta = +25°C, CL = 6 pF Ta = +25°C, CL = 6 pF
0 5 6
1.0
0.8
0.6
0.4
0.2
0
VDD [V]
IDD1
[μA]
1 2 3 4
0 5 6
1.0
0.8
0.6
0.4
0.2
0
VDD [V]
IDD3
[μA]
1 2 3 4
3. Current consumption during operation
vs. Input clock characteristics 4. Standby current
vs. Temperature characteristics
Ta = +25°C, CL = 6 pF CL = 6 pF
0
50
45
40
35
30
25
20
15
10
5
0
IDD2
[μA]
100 200 300 400 500
SCLfrequency [kHz]
VDD = 5.0 V
VDD = 3.0 V
–40 75 85
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Ta [°C]
IDD1
[μA]
–25 0 25 50
VDD = 5.0 V
VDD = 3.0 V
5. Standby current v s. Cg characteristics 6. Oscillation frequency vs. Cg characteristics
Ta = +25°C, CL = 6 pF Ta = +25°C, CL = 6 pF
0 6 8 10
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
I
DD1
[μA] V
DD
= 5.0 V
V
DD
= 3.0 V
2 4
C
g
[pF]
100
80
60
40
20
0
–20
–40
–60
–80
–100
Δf/f
[ppm]
0 2 4 6
Cg [pF] 8 10
VDD = 5.0 V
VDD = 3.0 V
2-WIRE REAL-TIME CLOCK
S-35390A Rev.4.0_00
Seiko Instruments In c.
44
7. Oscillation frequency vs. VDD characteristics 8. Oscillation frequency
vs. Temperature characteristics
Ta = +25°C, Cg = 7.5 pF Cg = 7.5 pF
50
40
30
20
10
0
–10
–20
–30
–40
–50
Δf/f
[ppm]
0 5 6
VDD [V]
1 2 3 4
20
0
–20
–40
–60
–80
–100
–120
–140
Δf/f
[ppm]
–40 75 85
Ta [°C]
–25 0 25 50
VDD = 5.0 V
VDD = 3.0 V
9. Oscillation start time v s. Cg characteristics 10. Output current characteri stics 1
(VOUT vs. IOL1)
Ta = +25°C
INT1
pin,
INT2
pin, Ta =
+25°C
0
500
450
400
350
300
250
200
150
100
50
0
tSTA
[ms]
2 8 10
4 6
Cg [pF]
VDD = 5.0 V
VDD = 3.0 V
0
50
40
30
20
10
0
IOL1
[mA]
1 2 3 4
VOUT [V]
VDD = 5.0 V
VDD = 3.0 V
11. Output current characteristics 2
(VOUT vs. IOL2) 12. BLD detection, release voltage, VDDT (min.)
vs. Temperature characteristics
SDA pin, Ta = +25°C CL = 6 pF
0
50
40
30
20
10
0
IOL2
[mA]
0.5 1 1.5 2
VOUT [V] 2.5
VDD = 5.0 V
VDD = 3.0 V
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
BLD
[V]
–40 75 85
–25 0 25 50
Ta [°C]
Release voltage
VDDT (min.)
Detection voltage
No. FJ008-A-P-SD-2.1
No.
TITLE
SCALE
UNIT mm
SOP8J-D-PKG Dimensions
Seiko Instruments Inc.
FJ008-A-P-SD-2.1
0.4±0.05
1.27
0.20±0.05
5.02±0.2
14
85
No.
TITLE
SCALE
UNIT mm
5
8
1
4
ø2.0±0.05
ø1.55±0.05 0.3±0.05
2.1±0.1
8.0±0.1
5°max.
6.7±0.1
2.0±0.05
Seiko Instruments Inc.
Feed direction
4.0±0.1(10 pitches:40.0±0.2)
SOP8J-D-Carrier Tape
No. FJ008-D-C-SD-1.1
FJ008-D-C-SD-1.1
No.
TITLE
SCALE
UNIT mm
QTY. 2,000
2±0.5
13.5±0.5
60°
2±0.5
ø13±0.2
ø21±0.8
Seiko Instruments Inc.
Enlarged drawing in the central part
SOP8J-D-Reel
No. FJ008-D-R-SD-1.1
FJ008-D-R-SD-1.1
No.
TITLE
SCALE
UNIT mm
QTY. 4,000
2±0.5
13.5±0.5
60°
2±0.5
ø13±0.2
ø21±0.8
Seiko Instruments Inc.
Enlarged drawing in the central part
SOP8J-D-Reel
No. FJ008-D-R-S1-1.0
FJ008-D-R-S1-1.0
No.
TITLE
SCALE
UNIT
Seiko Instruments Inc.
TSSOP8-E-PKG Dimensions
No. FT008-A-P-SD-1.1
FT008-A-P-SD-1.1
0.17±0.05
3.00 +0.3
-0.2
0.65
0.2±0.1
14
5
8
mm
No.
TITLE
SCALE
UNIT
Seiko Instruments Inc.
ø1.55±0.05
2.0±0.05
8.0±0.1 ø1.55 +0.1
-0.05
(4.4)
0.3±0.05
1
45
8
4.0±0.1
Feed direction
TSSOP8-E-Carrier Tape
No. FT008-E-C-SD-1.0
FT008-E-C-SD-1.0
+0.4
-0.2
6.6
mm
No.
TITLE
SCALE
UNIT
Seiko Instruments Inc.
Enlarged drawing in the central part
No. FT008-E-R-SD-1.0
2±0.5
ø13±0.5
ø21±0.8
13.4±1.0
17.5±1.0
3,000
QTY.
TSSOP8-E-Reel
FT008-E-R-SD-1.0
mm
No.
TITLE
SCALE
UNIT
Seiko Instruments Inc.
Enlarged drawing in the central part
2±0.5
ø13±0.5
ø21±0.8
13.4±1.0
17.5±1.0
4,000
QTY.
TSSOP8-E-Reel
FT008-E-R-S1-1.0
mm
No. FT008-E-R-S1-1.0
1.97±0.03
0.2±0.05
0.48±0.02
0.08
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
SNT-8A-A-PKG Dimensions
PH008-A-P-SD-2.0
No. PH008-A-P-SD-2.0
0.5
+0.05
-0.02
123 4
56
78
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
PH008-A-C-SD-1.0
SNT-8A-A-Carrier Tape
No. PH008-A-C-SD-1.0
Feed direction
4.0±0.1
2.0±0.05
4.0±0.1
ø1.5 +0.1
-0
ø0.5±0.1
2.25±0.05
0.65±0.05
0.25±0.05
2134
7865
5°
12.5max.
9.0±0.3
ø13±0.2
(60°) (60°)
Enlarged drawing in the central part
QTY.
PH008-A-R-SD-1.0
No.
TITLE
SCALE
UNIT mm
Seiko Instruments Inc.
SNT-8A-A-Reel
No. PH008-A-R-SD-1.0
5,000
No.
TITLE
SCALE
UNIT mm
SNT-8A-A-Land Recommendation
Seiko Instruments Inc.
PH008-A-L-SD-3.0
0.3
0.20.3
0.20.3
0.52
2.01
0.52
No. PH008-A-L-SD-3.0
0.3 0.2
Caution Making the wire pattern under the package is possible. However, note that the package
may be upraised due to the thickness made by the silk screen printing and of a solder
resist on the pattern because this package does not have the standoff.
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