Rev.2.4_00
3-WIRE REAL-TIME CLOCK S-35190A
Seiko Instruments Inc. 1
The S-35190A is a CMOS 3-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 this IC 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, this IC 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 power-off
the main power supply, after the voltage is restored.
This IC has the function to correct advance/delay of the clock data speed, in the wide range,
which is caused by 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 to 5.5 V
• Built-in clock-correction function
• Built-in free user register
• 3-wire (MICROWIRE) CPU interface
• Built-in alarm interrupter
• Built-in flag generator during detection of low power voltage or at power-on
• Auto calendar up to the year 2099, automatic leap year calculation function
• Built-in constant voltage circuit
• Built-in 32.768 kHz crystal oscillator (Cd built in, Cg external)
• Package : 8-Pin SOP (JEDEC), 8-Pin TSSOP, SNT-8A
• Lead-free product
Applications
• Mobile game devices
• Mobile AV devices
• Digital still cameras
• Digital video cameras
• Electronic power meters
• DVD recorders
• TVs, VCRs
• Mobile phones, PHS
• Car navigation
Package
Drawing Code
Package Name Package Tape Reel Land
8-Pin SOP (JEDEC) FJ008-A FJ008-D FJ008-D −
8-Pin TSSOP FT008-A FT008-E FT-008E −
SNT-8A PH008-A PH008-A PH008-A PH008-A
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
2
Pin Configuration
1
2
3
4
8
7
6
5
8-Pin SOP (JEDEC)
Top view
XOUT
VSS
XIN
INT
SIO
SCK
VDD
CS
(1.84 × 1.97 × 0.6 max)
Figure 1 Pin Configuration (S-35190A-J8T1G)
1
2
3
4
8
7
6
5
8-Pin TSSOP
Top view
XOUT
XIN
VSS
INT
SIO
CS
VDD
SCK
Figure 2 Pin Configuration (S-35190A-T8T1G)
SNT-8A
Top view
1
2
3
4
8
7
6
5
XOUT
XIN
VSS
INT
SIO
CS
VDD
SCK
Figure 3 Pin Configuration (S-35190A-I8T1G)
List of Pin
Table 1
Pin No. Symbol Description I/O Configuration
1 INT Output pin for
Interrupt signal Output Nch open-drain output
(no protective diode at VDD)
2 XOUT
3 XIN
Connection pin for
crystal oscillator − −
4 VSS GND pin − −
5 CS
Input pin for chip
select Input CMOS input
(built-in pull-down resistor. no protective diode at VDD)
6 SCK Input pin for serial
clock Input CMOS input
(no protective diode at VDD)
7 SIO
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 − −
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 3
Pin Function
• CS (input for chip select) pin
This pin is to input chip select, has a pull-down resistor. Communication is available when this pin is in “H” level. If not
using communication, set this pin “L” or open.
• SCK (input for serial clock) pin
This pin is to input a clock pulse for serial interface. When the CS pin is in “H”, the SIO pin inputs/outputs data by
synchronizing with the clock pulse. When the CS pin is in “L” or open, the
SCK pin does not accept inputting a clock
pulse.
• SIO (I/O for serial data) pin
This pin is to data input/output for serial interface. When the CS pin is in “H”, the SIO pin inputs/outputs data by
synchronizing with a clock pulse from the SCK pin. The status is in high impedance when the CS pin is in “L” or open,
so that the S-35190A does not transmit data. Setting the CS pin to “H” level from “L” or open, this SIO pin goes in the
input status so that it receives the command data. This pin has CMOS input and Nch open drain output.
• XIN, XOUT (crystal oscillator connect) pin
Connect a crystal oscillator between XIN and XOUT.
• INT (output for interrupt signal) 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, alarm 2 interrupt, output of user-set frequency, per-minute edge interrupt, minute-periodical interrupt 1,
minute-periodical interrupt 2, or 32.768 kHz output. This pin has Nch open drain output.
• 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”.
• VSS pin
Connect the VSS pin to GND.
Equivalent Circuits of I/O Pin
SCK
Figure 4
SCK pin
SIO
Figure 5 SIO pin
CS
Figure 6 CS pin
INT
Figure 7 INT pin
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
4
Block Diagram
Real-time data register
Status register 1
Oscillator
SCK
SIO
Low power supply
voltage detector
VDD
VSS
Comparator 1
Second
Minute
Hour
Day of
the week
Day
Month
Year
Shift register Serial
interface
XIN
XOUT
Comparator 2
Clock correction register
INT controller 1
Divider,
Timing generator
INT controller 2
Constant-voltage
circuit
Status register 2
INT register 1
INT register 2
Power-on
detector
Free register
CS
INT
Figure 8
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 5
Absolute Maximum Ratings
Table 2
Parameter Symbol Applicable Pin Rating Unit
Power supply voltage VDD − V
SS − 0.3 to VSS + 6.5 V
Input voltage VIN CS, SCK , SIO VSS − 0.3 to VSS + 6.5 V
Output voltage VOUT SIO, INT 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 condensation or frost. Condensation and frost cause short circuiting between 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 conditions.
Recommended Operation Conditions
Table 3
(VSS = 0 V)
Parameter Symbol Conditions Min. Typ. Max. Unit
Power supply voltage*1 VDD Ta = −40 to +85°C 1.3 3.0 5.5 V
Time keeping power
supply voltage *2
VDDT Ta = −40 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 Table 8 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 4
(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.)
Parameter Symbol Conditions 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 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
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
6
DC Electrical Characteristics
Table 5 DC Characteristics (VDD = 3.0 V)
(Ta
=
−
40 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.)
Parameter Symbol Applicable Pin Conditions Min. Typ. Max. Unit
Current
consumption 1 IDD1 − Out of communication − 0.25 0.93
µA
Current
consumption 2 IDD2 − During communication
(SCK = 100 kHz) − 3.3 8
µA
Input current
leakage 1 IIZH
SCK , SIO VIN = VDD −0.5 − 0.5 µA
Input current
leakage 2 IIZL SCK , SIO VIN = VSS −0.5 − 0.5 µA
Input current 1 IIH1 CS VIN = VDD 2 6 16 µA
Input current 2 IIH2 CS VIN = 0.4 V 40 100 300 µA
Input current 3 IIH3 CS VIN = 1.0 V − 215 − µA
Output current
leakage 1 IOZH SIO, INT VOUT = VDD −0.5 − 0.5 µA
Output current
leakage 2 IOZL SIO, INT VOUT = VSS −0.5 − 0.5 µA
Input voltage 1 VIH CS,
SCK , SIO − 0.8 × VDD − VSS + 5.5 V
Input voltage 2 VIL CS, SCK , SIO − V
SS − 0.3 − 0.2 × VDD V
Output current 1 IOL1 INT VOUT = 0.4 V 3 5 − mA
Output current 2 IOL2 SIO VOUT = 0.4 V 5 10 − mA
Power supply
voltage detection
voltage
VDET − − 0.65 1 1.35 V
Table 6 DC Characteristics (VDD = 5.0 V)
(Ta
=
−
40 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.)
Parameter Symbol Applicable Pin Conditions Min. Typ. Max. Unit
Current
consumption 1 IDD1 − Out of communication − 0.3 1.1
µA
Current
consumption 2 IDD2 − During communication
(SCK = 100 kHz) − 6 14
µA
Input current
leakage 1 IIZH
SCK , SIO VIN = VDD −0.5 − 0.5
µA
Input current
leakage 2 IIZL SCK , SIO VIN = VSS −0.5 − 0.5
µA
Input current 1 IIH1 CS VIN = VDD 8 16 50
µA
Input current 2 IIH2 CS VIN = 0.4 V 40 150 350
µA
Input current 3 IIH3 CS VIN = 2.0 V − 610 − µA
Output current
leakage 1 IOZH SIO, INT VOUT = VDD −0.5 − 0.5
µA
Output current
leakage 2 IOZL SIO, INT VOUT = VSS −0.5 − 0.5
µA
Input voltage 1 VIH CS,
SCK , SIO − 0.8 × VDD − V
SS + 5.5 V
Input voltage 2 VIL CS, SCK , SIO − VSS−0.3 − 0.2 × VDD V
Output current 1 IOL1 INT VOUT = 0.4 V 5 8 − mA
Output current 2 IOL2 SIO VOUT = 0.4 V 6 13 − mA
Power supply
voltage detection
voltage
VDET − − 0.65 1 1.35
V
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 7
AC Electrical Characteristics
Table 7 Measurement Conditions
Input pulse voltage VIH = 0.8 × VDD, VIL = 0.2 × VDD
Input pulse rise/fall time 20 ns
Output determination voltage VOH = 0.8 × VDD, VOL = 0.2 × VDD
Output load 80 pF + pull-up resistor 10 kΩ
SIO
C = 80 pF
V
DD
R = 10 kΩ
Remark The power supplies of the IC
and load have the same
electrical potential.
Figure 9 Output Load Circuit
Table 8 AC Electrical Characteristics
(Ta = −40 to +85°C)
VDD *2 ≥ 1.3 V VDD *2 ≥ 3.0 V
Parameter Symbol Min. Typ. Max. Min. Typ. Max.
Unit
Clock pulse width tSCK 5 − 250000 1 − 250000 µs
Setup time before CS rise tDS 1 −
− 0.2 − − µs
Hold time after CS rise tCSH 1 − − 0.2 − − µs
Input data setup time tISU 1 − − 0.2 − − µs
Input data hold time tIHO 1 − − 0.2 − − µs
Output data definition time *1 tACC − − 3.5 − − 1 µs
Setup time before CS fall tCSS 1 − − 0.2 − − µs
Hold time after CS fall tDH 1 − − 0.2 − − µs
Input rise/fall time tR, tF − − 0.1 − − 0.05 µs
*1. Since the output format of the SIO pin is Nch open-drain output, output data definition 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 power supply voltage, refer to “ Recommended Operation Conditions”.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
8
SIO
t
DS
t
CSH
t
DS
SCK
t
DH
t
CSS
t
DH
CS
Figure 10 Timing Diagram 1 during 3-wire Communication
Input data
80%
20%
t
F
t
R
t
ISU
t
IHO
t
R
, t
F
20%20%
80%80%
80%
20%
SCK
Figure 11 Timing Diagram 2 during 3-wire Communication
Output data
80%
20%
50% 50% 50%
t
SCK
t
SCK
t
ACC
20%
80%
20%
SCK
Figure 12 Timing Diagram 3 during 3-wire Communication
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 9
Configuration of Data Communication
1. Configuration of data communication
After setting the CS pin “H”, transmit the 4-bit fixed code “0110”, after that, transmit a 3-bit command and 1-bit Read/Write
command. Next, data is output or input from B7. Regarding details, refer to “ Serial Interface”.
Command
0 1 1 0 C2 C1 C0 R / W
Fixed code
Read/Write bit
B7 B6 B5 B4 B3 B2 B1 B0
1-byte data
Figure 13 Data Communication
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
10
2. Configuration of command
8 types of command are available for the S-35190A, The S-35190A does Read/Write the various registers by inputting
these fixed codes and commands. The S-35190A does not perform any operation with any codes and commands other
than those below.
Table 9 List of Command
Command
Data
Fixed
Code
C2 C1 C0
Description
B7 B6 B5 B4 B3 B2 B1 B0
0 0 0
Status register 1 access
RESET
*1 24/12 SC0*2 SC1*2 INT1*3 INT2*3 BLD*4 POC*4
0 0 1
Status register 2 access INT1FE INT1ME INT1AE
32kE SC2*2 SC3*2
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
INT register 1 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
INT register 1 access
(output of user-set frequency)
(INT1ME = 0, INT1FE = 1)
1 Hz 2 Hz 4 Hz 8 Hz 16 Hz SC4 *2 SC5
*2 SC6 *2
1 0 1
INT register 2 access
(alarm time 2: week/hour/minute)
(INT2AE = 1)
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 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-35190A initializes by writing “1” in this register.
*2. Scratch bit. A R/W-enabled, user-free register.
*3. Read-only flag. Valid only when using the alarm function. When the alarm time matches, this flag is set to “1”, and it is
cleared to “0” when Read.
*4. Read-only flag. “POC” is set to “1” when power is applied. It is cleared to “0” when Read. Regarding “BLD”, refer to “
Low Power Supply Voltage Detection Circuit”.
*5. Test bit for SII. Be sure to set “0” in use.
*6. No effect by Write. It is “0” when Read.
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 11
Configuration of Register
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 in B7, month, day, day
of the week, hour, minute, second in B0, in 7-byte. When you skip the procedure to access the data of year, month, day,
day of the week, Read/Write real-time data 2 access. In this case, transmit/receive the data of hour in B7, minute, second
in B0, in 3-byte.
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 14 Real-time Data Register
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
12
Year data (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: 2053 (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: December (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 changed 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 a 12-hour expression, write 0; AM, 1; PM in the PM/AM bit. In a 24-hour expression, users can 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 expression): 12 p.m. (H1, H2, H4, H8, H10, H20, AM/PM, 0) = (0, 1, 0, 0, 1, 0, 1, 0)
Example (24-hour expression): 22 (H1, H2, H4, H8, H10, H20, AM/PM, 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)
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 13
2. Status register 1
Status register 1 is a 1-byte register that is used to display and set various modes. The bit configuration is 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 15 Status Register 1
B0 : POC
This flag is used to confirm whether the power is on. The power-on detector operates at power-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 to “ 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 the power supply voltage. This flag is set to “1” once, is not set to “0” again even if the power
supply increases to the level of detection voltage (VDET) or more. This flag 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
Detection Circuit”.
B2 : INT2, B3 : INT1
This flag indicates the time set by alarm and when the time has reached it. This flag is set to “1” when the time that
users set by using the alarm interrupt function has come. The INT1 flag in “1” at alarm 1 interrupt mode, the INT2 flag
in “1” at alarm 2 interrupt mode. This flag is Read-only. This flag is read once, is set to “0” automatically.
B4 : SC1, B5 : SC0
These flags are SRAM type registers, they are 2 bits as a whole, can be freely set by users.
B6 : 24
/
12
This flag is used to set 12-hour or 24-hour expression.
0 : 12-hour expression
1 : 24-hour expression
B7 : RESET
The internal IC is initialized by setting this bit to “1”. This bit is Write-only. It is always “0” when Read. 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”.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
14
3. Status register 2
Status register 2 is a 1-byte register that is used to display and set various modes. The bit configuration is shown below.
B7
INT1FE INT1ME
R/W R/W
32kE
B6 B5 B4 B3 B2 B1 B0
SC3 SC2
INT1AE
R/W
R/W: Read/Write
R/W R/W R/W R/W R/W
INT2AE TEST
Figure 16 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
This is an enable bit for alarm 2 interrupt. When this bit is “0”, alarm 2 interrupt is disabled. When it is “1”, it is enabled.
To use alarm 2 interrupt, access the INT register 2 after enabling this flag.
Caution Note that alarm 2 interrupt is output from the INT pin regardless of the settings in flags B4 to B7.
B2 : SC3, B3 : SC2
These are 2-bit SRAM type registers that can be freely set by users.
B4 : 32kE, B5 : INT1AE, B6 : INT1ME, B7 : INT1FE
These bits are used to select the output mode for the INT pin. Table 10 shows how to select the mode. To use alarm
1 interrupt, access the INT register 1 after setting the alarm 1 interrupt mode.
Table 10 Output Modes for INT Pin
32kE INT1AE INT1ME INT1FE INT Pin Output Mode
0 0 0 0 No interrupt
0 −*1 0 1 Output of user-set frequency
0 −*1 1 0 Per-minute edge 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).
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 15
4. INT register 1 and INT register 2
The INT register 1 is to set up the output of user-set frequency, or to set up alarm 1 interrupt. The INT register 2 is for
setting alarm 2 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; this register works as the alarm-time data register. In the INT register
1, if selecting the output of user-set frequency by status register 2; this register works as the data register to set the
frequency for clock output. From the INT pin, a clock pulse and alarm interrupt are output, according to the or-condition
that these two registers have.
(1) Alarm interrupt
Users can set the alarm time (the data of day of the week, hour, minute) by using the INT register 1 and 2 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 by the BCD code. Do not set a nonexistent day. Users are necessary to set
up the alarm-time data according to the 12/24 hour expression that they set by using the status register 1.
H8 H4 H2
H1
A1mE
m8
m4
m2
m1
H20
H10
m10 m20 m40
H8
H4
H2
H1
A2mE
m8
m4
m2
m1
H20
H10
m10 m20 m40
A
M/
PM
A
1WE
0
0
W4
W2 W1
B7 B0
0 0
INT register 1
0
0
W4
W2
W1 0
0
INT register 2
A
2WE
A
1HE
A
2HE
A
M/
PM
B7 B0
B7 B0
B7 B0
B7 B0
B7 B0
Figure 17 INT Register 1 and INT Register 2 (Alarm-Time Data)
The INT register 1 has A1WE, A1HE, A1mE at B0 in each byte. It is possible to make data valid; 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 INT register 2.
Setting example: alarm time “7:00 pm” in the INT register 1
(a) 12-hour expression (status register 1 B6 = 0)
set up 7:00 PM
Data written to INT register 1
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).
(b) 24-hour expression (status register 1 B6 = 1)
set up 19:00 PM
Data written to INT register 1
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 PM/AM flag along with the time setting.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
16
(2) Output of user-set frequency
The INT register 1 is a 1-byte data register 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. SC4 to SC6 is 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
SC4 16 Hz
4 Hz
R/W
R/W: Read/Write
R/W R/W R/W R/W R/W
SC5 SC6
2 Hz 1 Hz
Figure 18 INT Register 1 (Data Register for Output Frequency)
Example: B7 to B3 = 50h
16 Hz
8 Hz
4 Hz
2 Hz
INT pin output
Status register 2
• Set to INT1FE = 1
1 Hz
Figure 19 Example of Output from INT Register 1 (Data Register for Output Frequency)
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 17
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 to Clock-Correction”.
B7
R/W R/W
V3
B6 B5 B4 B3 B2 B1 B0
V5 V4
V2
R/W
R/W: Read/Write
R/W R/W R/W R/W R/W
V6 V7
V1 V0
Figure 20 Clock-Correction Register
6. Free register
The 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: Read/Write
R/W R/W R/W R/W R/W
F6 F7
F1 F0
Figure 21 Free Register
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
18
Power-on Detector and Register Status
The power-on detection circuit operates by power-on the S-35190A, as a result each register is cleared; each register 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 : “01h”
INT register 1 : “80h”
INT register 2 : “00h”
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, the status register 2 goes in the mode the output of user-set frequency, so that 1 Hz clock pulse is output from
the INT pin. When “1” is set in the POC flag, be sure to initialize. The POC flag is set to “0” due to initialization so that the
output of user-set frequency mode is cleared. (Refer to “ Register Status After Initialization”.)
For the regular operation of power-on detection circuit, as seen in Figure 22, the period to power-up the S-35190A is that
the voltage reaches 1.3 V within 10 ms after setting the IC’s power supply voltage at 0 V. When the power-on detection
circuit is not working normally is; the POC flag (B0 in the status register) is not in “1”, or 1 Hz is not output from the INT pin.
In this case, power-on the S-35190A once again because the internal data may be in the indefinite status.
Do not transmit data immediately after power-on at least 0.5 sec because the power-on detection circuit is operating.
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 the S-35190A.
Figure 22 How to Raise the Power Supply Voltage
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 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 (day 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 initialization is set.
Refer to Figure 23.)
Status register 2 : “00h”
INT register 1 : “00h”
INT register 2 : “00h”
Clock correction register : “00h”
Free register : “00h”
CS
SCK
0000
1
0
1
0 0 0 11 0 X
SIO
Fixed code + command
0 0 0000110 01
Fixed code + command
0
0
0
0
1
00
0
Write to status register 1 Read from status register 1
B5 : Not reset
B5
B7
Write “1” to reset flag and
SC0.
Figure 23 Status Register 1 Data at Initialization
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
20
Low Power Supply Voltage Detection Circuit
The S-35190A 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 held in the BLD flag. After initialization, or once
the BLD flag is read, the BLD flag is automatically set to “0” to restart the sampling operation.
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.
V
DD
BLD flag
Stop Stop Stop
Sampling pulse
Hysteresis width
0.15 V approximately
BLD flag reading
Detection
voltage
Release
voltage
15.6 ms
1 s 1 s
Figure 24 Timing of Low Power Supply Voltage Detection Circuit
Circuits Power-on and Low Power Supply Voltage Detection
Figure 25 shows the changes of the POC flag and BLD flag due to VDD fluctuation.
V
DD
BLD flag
Status register 1
reading
POC flag
Low power supply
voltage detection
voltage
Low power supply
voltage detection
voltage V
SS
Figure 25 POC Flag and BLD Flag
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 21
Correction of Nonexistent Data and End-of-Month
When users write the real-time data, the S-35190A checks it. In case that the data is invalid, the S-35190A does the
following procedures.
1. Processing of nonexistent data
Table 11 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 to XF 00
Hour data *1 12-hour 0 to 11 12 to 19, 2X, 3X, 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 a 12-hour expression, Write the PM/AM flag (B1 in hour data in the real-time data register).
In 24-hour expression, the PM/AM flag in the real-time data register is omitted. However in the flag in Read, users are
able to read 0; 0 to 11, 1; 12 to 23.
*2. Processing of nonexistent data, regarding second data, is done by a carry pulse which is generated one sec after, after
Write. At this point the carry pulse is sent to the minute-counter.
2. Correction of end-of-month
A nonexistent day, such as February 30 and April 31, is set to the first day of the next month.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
22
INT Pin Output Mode
These are selectable for the INT pin output mode;
Alarm 1 interrupt, alarm 2 interrupt, the output of user-set frequency, per-minute edge interrupt output, minute-periodical
interrupt output 1 and 2, 32.768 kHz output.
In alarm 1 interrupt/output of frequency; set data in the INT register 1. In alarm 2 interrupt, set data in the INT register 2. To
swith the output mode, use the status register 2. Refer to “3. Status register 2” in “ Configuration of Register”.
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 INT register 1 or 2. Alarm 2 interrupt is dependent from other
modes. Regardless of other settings of mode if alarm 2 interrupt was generated, be careful that “L” is output from the INT
pin. In 32.768 kHz output/per-minute edge interrupt output/minute-periodical interrupt output, it is unnecessary to set data
in the INT register 1 or 2 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 INT 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, minute in the INT register 1 or 2, set the data of year, month,
day in the INT register 1 or 2. Refer to “4. INT register 1 and INT register 2” in “ Configuration of Register”.
Alarm setting of W (day of the week), H (hour), m (minute)”
INT register x alarm enable flag
• AxHE = AxmE = AxWE = “1”
H h (m − 1) m 59s
Change by program Change by program
OFF
Alarm time matches
H h m m 00 s 01 s 59 s H h (m + 1) m 00
s
Real-time data
*1
INT pin
INT1AE/INT2AE
Status register 2 setting
• Alarm 1 interrupt
32kE
=
0, INT1ME
=
INT1FE = 0
• Alarm 2 interrupt
None
mx Hx Wx
Comparator
INT register 1
INT register 2
Alarm interrupt
Real-time data
Minute
Hour
Second
Day Year Month
Change by program
Period when alarm time matches
W (day of the week)
Day of
the week
*1. If users clear INT1AE/INT2AE once; “L” is not output from the INT pin by setting INT1AE/INT2AE enable again, within
a period when the alarm time matches real-time data.
Figure 26 Alarm Interrupt Output Timing (1/2)
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 23
Alarm setting of “H (hour)”
INT register x alarm enable flag
• AxWE = AxmE = “0”, AxHE = “1”
Comparator Alarm interrupt
Real-time data
(H
−
1) h 59 m 59 s
Change by program Change by program
OFF
Alarm time matches
H h 00 m 00 s 01 s 59 s H h 01 m 00 s
Change by program
Real-time data
Period when alarm time matches
*1
H h 59 m 59 s (H
+
1) h 00 m 00 s
OFF
Change by program
Alarm time
matches
*2
*1
INT register 1
INT register 2
INT1AE / INT2AE
INT pin
Status register 2 setting
• Alarm 1 interrupt
32kE
=
0
, INT1ME
=
INT1FE = 0
• Alarm 2 interrupt
None
mx Hx Wx Dx Mx Yx
Second Minute Hour
Day of
the week
Day Month Year
*1. If users clear INT1AE/INT2AE once; “L” is not output from the INT pin by setting INT1AE/INT2AE enable again, within
a period when the alarm time matches real-time data.
*2. If turning the alarm output on by changing the program, within the period when the alarm time matches real-time data,
“L” is output again from the INT pin when the minute is counted up.
Figure 27 Alarm Interrupt Output Timing (2/2)
2. Output of user-set frequency
The output of user-set frequency is the function to output the frequency which is selected by using data, from the INT pin,
in the AND-form. Set up the data of frequency in the INT register 1.
Refer to “4. INT register 1 and INT register 2” in “ Configuration of Register”.
INT1FE
INT pin
OFF
Change by program
Status register 2 setting
32kE = 0, INT1AE = Don’t care (0 or 1), INT1ME = 0
Free-run output starts
Figure 28 Output Timing of User-set Frequency
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
24
3. Per-minute edge interrupt output
Per-minute edge interrupt output is the function to output “L” from the INT pin, when the first minute-carry processing is
done, after selecting the output mode. To set the pin output to “H”, set “0” in INT1ME in the status register 2 to turn off the
output mode of per-minute edge interrupt.
INT1ME
INT pin
OFF
"L" is output again if this period is within 7.9 ms
*1
.
Change by program
Status register 2 setting
• 32kE = 0, INT1AE = Don’t care (0 or 1), INT1FE = 0
Minute-carry processing Minute-carry
processing
*1. Pin output is set to “H” by disabling the output mode within 7.9 ms, because the signal of this procedure is maintained
for 7.9 ms. Note that pin output is set to “L” by setting enable the output mode again.
Figure 29 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 INT pin, when
the first minute-carry processing is done, after selecting the output mode.
INT1FE,
INT1ME
INT pin
"L" is output again if this period is within 7.9 ms
*1
.
Change by program (OFF)
Status register 2 setting
• 32kE = 0, INT1AE = 0
Minute-carry
processing
"H" is output again if this period is within 7.9 ms.
"L" is output at the next minute-carry processing
30 s 30 s 30 s 30 s 30 s 30 s 30 s 30 s 30 s
Minute-carry
processing
Minute-carry
processing Minute-carry
processing
Minute-carry
processing
*1. Setting the output mode disable makes the pin output “H”, while the output from the INT pin is in “L”. Note that pin
output is set to “L” by setting enable the output mode again.
Figure 30 Timing of Minute-periodical Interrupt Output 1
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 25
5. Minute-periodical interrupt output 2
The output of minute-periodical interrupt 2 is the function to output “L”, for 7.9 ms, from the INT pin, synchronizing with
the first minute-carry processing after selecting the output mode. However, in Read in the real-time data register, the
procedure delays at max. 0.5 sec thus output “L” from the INT pin also delays at max. 0.5 sec. In Write in the real-time
data register, some delay is made in the output period due to Write timing and the second-data during Write.
(a) During normal operation
7.9 ms 7.9 ms 7.9 ms
60 s 60 s
INT pin
Minute-carry processing Minute-carry processing Minute-carry processing
(b) During Read in the real-time data register
INT pin
7.9 ms
Serial
communication
7.9 ms 7.9 ms
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)
(c) During Write in the real-time data register
INT pin
7.9 ms
Real-time data
write timing
7.9 ms 7.9 ms
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 31 Timing of Minute-periodical Interrupt Output 2
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
26
6. Operation of power-on detection circuit
When power is applied to the S-35190A, 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 INT pin.
Status register 2 setting
INT1FE
INT pin
OFF
0.5 s 0.5 s
Change by reset command32kE = 0, INT1AE = INT1ME = 0,
Figure 32 Output Timing of INT Pin during Operation of Power-on Detection Circuit
Function to Clock-Correction
The function to clock-correction is to correct advance/delay of the clock due to the deviation of oscillation frequency, in
order to make a high precise clock. For correction, the S-35190A adjusts the clock pulse by using a certain part of the
dividing circuit, not adjusting the frequency of the crystal oscillator. Correction is performed once every 20 seconds (or 60
seconds). The minimum resolution is approx. 3 ppm (or approx. 1 ppm) and the S-35190A corrects in the range of −195.3 to
+192.2 ppm (or of −65.1 to +64.1 ppm). (Refer to Table 12.) 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 12 Function to Clock-Correction
B0 = 0 B0 = 1
Correction Every 20 seconds Every 60 seconds
Minimum resolution 3.052 ppm 1.017 ppm
Correction range −195.3 to +192.2 ppm −65.1 to +64.1 ppm
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 27
1. How to calculate
(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 oscillation frequency
actual measurement value
*2
) (Target oscillation 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 “(a) Calculation
example 1”.
*2. Measurement value when 1 Hz clock pulse is output from the INT pin.
*3. Target value of average frequency when the clock correction function is used.
*4. Refer to Table 12.
(a) Calculation example 1
In case of current oscillation frequency actual measurement value = 1.000070 [Hz], target oscillation frequency =
1.000000 [Hz], B7 = 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 B6 to B0 of the clock correction register.
Thus, set the clock correction register:
(B7, B6, B5, B4, B3, B2, B1, B0) = (0, 1, 0, 1, 0, 1, 1, 0)
(2) If current oscillation frequency < target frequency (in case the clock is slow)
Correction value = Integral value (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 the calculated value is from 0 to 62.
(a) Calculation example 2
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], target oscillation frequency =
1.000000 [Hz]. B7 = 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 register:
(B7, B6, B5, B4, B3, B2, B1, B0) = (1, 1, 0, 1, 1, 0, 0, 0)
(b) Calculation example 3
In case of current oscillation frequency actual measurement value = 0.999920 [Hz], target oscillation frequency =
1.000000 [Hz], B7 = 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
Thus, this calculated value exceeds the correctable range 0 to 62,
B7 = “1” (minimum resolution = 1.017 ppm) indicates the correction is impossible.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
28
2. Setting value for register and correction value
Table 13 Setting Value for Register and Correction Value (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 14 Setting Value for Register and Correction Value (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
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 29
3. How to confirm setting value for register and result of correction
The S-35190A does not adjust the frequency of the crystal oscillation by using the clock-correction function. 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 cycle of 1 Hz clock pulse output from the INT pin changes once in 20 times or 60 times, as shown in
Figure 33.
INT pin
(1 Hz output)
a a a a
b
B0 = 0, a : 19 times, b : Once
B0 = 1, a : 59 times, b : Once
19 times or 59 times Once
Figure 33 Confirmation of Correction Result
Measure a and b by using the frequency counter*1. Calculate the average frequency (Tave) based on the measurement
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 example: 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 high-accuracy frequency counter of 7 digits or more.
Caution Measure the oscillation frequency under the usage conditions.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
30
Serial Interface
The S-35190A receives various commands via 3-wire serial interface to Read/Write data. Regarding transmission is as
follows.
1. Data Read
When data is input from the SIO pin in synchronization with the falling of the SCK clock after setting the CS pin to “H”, the
data is loaded internally in synchronization with the next rising of the
SCK clock. When W/R bit = “1” is loaded at the
eighth rising of the SCK clock, the state of data reading is entered. Data corresponding to each command is then output
in synchronization with the falling of the subsequent
SCK clock input. When the SCK clock is less than 8, the IC is in
the clock-wait status, and no processing is performed.
2. Data Write
When data is input from the SIO pin in synchronization with the falling of the
SCK clock after setting the CS pin to “H”, the
data is loaded internally in synchronization with the next rising of the SCK clock. When W/R bit = “0” is loaded at the
eighth rising of the
SCK clock, the state of data writing is entered. In this state, the data, which is input in synchronization
with the falling of the subsequent SCK clock input, is written to registers according to each command. In data Write, input
a clock pulse which is equivalent to the byte of the register. As well as in Read, when the
SCK clock is less than 8, the IC
is in the clock-wait status, and no processing is performed.
3. Data access
(1) Real-time data 1 access
64
8
1
01 0 0 1 1 0 X
During reading: Output mode switching
CS
SCK
SIO
Year data Second data
B0B7
During reading:
In
p
ut mode switchin
g
Fixed code +
command
R / W
B0 B7
16 56
Figure 34 Real-Time Data Access 1
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 31
(2) Real-time data 2 access
32
8
1
1 1 0 01 1 0 X
During reading: Output mode switching
CS
SCK
SIO
Hour data Second data
B0
B7
During reading:
Input mode switching
R / W
Minute data
B0
B7 B0
B7
Fixed code +
command
16 24
Figure 35 Real-Time Data 2 Access
(3) Status register 1 access and status register 2 access
8
1
CS
SCK
*1
00011 0 X
During reading: Output mode switching
SIO
Status data During reading:
Input mode switching
B0
B7
R / W
16
Fixed code +
command
*1. 0 : Status register 1 selected
1 : Status register 2 selected
Figure 36 Status Register 1 Access and Status Register 2 Access
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
32
(4) INT register 1 access and INT register 2 access
In Read/Write the INT register 1, data varies depending on the setting of the status register 2. Be sure to Read/Write
the INT register 1 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.
Read/Write the INT register 2 after setting INT2AE in the status register 2. When INT2AE is in “1”, the INT register 2
works as for setting the 3-byte alarm time data. The INT register 2 does not have the function to output the user-set
frequency. Regarding details of each data, refer to “4. INT register 1 and INT register 2” in “ Configuration of
Register”.
Caution Users cannot use both functions of alarm 1 interrupt and the output of user-set frequency
simultaneously.
32
8 1
0 1 0 1 1 0 X
During reading: Output mode switching
CS
SCK
SIO
Day of the
week data Minute data
B0
B7
During reading:
Input mode switching
*1
R / W
16 24
Hour data
B0
B7 B0
B7
Fixed code +
command
*1. 0 : INT register 1 selected
1 : INT register 2 selected
Figure 37 INT Register 1 Access and INT Register 2 Access
8
1
CS
SCK
0 0 1 0 1 1 0 X
During reading: Output mode switching
SIO
Frequency setting
data During reading:
Input mode switching
B0B7
R / W
16
Fixed code +
command
Figure 38 INT Register 1 (Data Register for output frequency) Access
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 33
(5) Clock correction register access
8
1
CS
SCK
0 1 1 0 1 1 0 X
During reading: Output mode switching
SIO
Clock correction
data During reading:
Input mode switching
B0
B7
R / W
16
Fixed code +
command
Figure 39 Clock Correction Register Access
(6) Free register access
8
1
CS
SCK
1 1 1 0 1 1 0 X
During reading: Output mode switching
SIO
Free register data During reading:
Input mode switching
B0B7
R / W
16
Fixed code +
command
Figure 40 Free Register Access
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
34
Flowchart of Initialization at Power-on and Example of Real-time Data Set-up
Figure 41 shows the flowchart of initialization at power-on and an example of real-time data set-up. Regarding how to apply
power, refer to “ Power-on Detection Circuit and Register Status”. It is unnecessary for users to comply with this
flowchart of real-time data strictly. And if using the default data at initializing, it is also unnecessary to set up again.
NO
YES
START
POC = 1
Power-on
Set 24-hour/12-hour
display to status register 1
Confirm data in status
register 1
OK
NG
Set real-time data 1
Read real-time data 1
Initialization after power-on
Example of real-time data setting
Wait for 0.5 s
Read status re
g
ister 1
POC = 0 NO
YES
BLD = 0
YES
TEST = 0
YES
END
Read status register 1
Read status register 1
Read status re
g
ister 2
NO
Initialize
(status register 1 B7 = 1)
NO
Figure 41 Example of Initialization Flowchart
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 35
Examples of Application Circuits
VCC
XOUT
XIN
S-35190A
SIO
VSS
VDD
SCK
VSS
VCC
CPU
INT
CS
System power supply
Cg
10 kΩ
10 kΩ
Caution 1. Because the I/O pin has no protective diode on the VDD side, the relation 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 42 Application Circuit 1
VSS
VCC
CPU
XOUT
XIN
S-35190A SIO
VSS
VDD
SCK
INT
CS
System power supply
Cg
10 kΩ
10 kΩ
Caution Start communication under stable condition after power-on the power supply in the system.
Figure 43 Application Circuit 2
Caution The above connection diagrams do not guarantee operation. Set the constants after performing
sufficient evaluation using the actual application.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
36
Adjustment of Oscillation Frequency
1. Configuration of oscillation
Since crystal oscillation is sensitive to external noise (the clock accuracy is affected), the following measures are
essential for optimizing the oscillation configuration.
(1) Place the S-35190A, crystal oscillator, and external capacitor (Cg) as close to each other as possible.
(2) Increase the insulation resistance between pins and the substrate wiring patterns of XIN and XOUT.
(3) Do not place any signal or power lines close to the oscillator.
(4) Locating the GND layer immediately below the oscillator is recommended.
(5) Locate the bypass capacitor adjacent to the power supply pin of the S-35190A.
S-35190A
XOUT
XIN
R
f
=
100 MΩ
R
d
=
100 kΩ
C
d
=
8 pF
C
g
C
d
R
d
R
f
Crystal oscillator: 32.768 kHz
C
L
= 6
pF
*1
C
g
= None
*2
to
9.1 pF
Parasitic capacitance
*3
Parasitic capacitance
*3
Oscillation internal constant
standard values:
*1. When setting the value for the crystal oscillator’s CL as 7 pF, connect Cd externally if necessary.
*2. Design the board so that the parasitic capacitance is 5 pF.
*3. The oscillator operates unless Cg is not connected. Note that the oscillation frequency is in the direction that it
advances.
Figure 44 Connection Diagram 1
XIN
Crystal
oscillator
XOUT
VSS
C
g
8
7
6
5
1
2
3
4
S-35190A
Locate the GND layer in the
layer immediately below
Figure 45 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 are subject to the variation of each component such as substrate parasitic
capacitance, parasitic resistance, crystal oscillator, and Cg. When configuring oscillator, pay
sufficient attention for them.
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 37
2. Measurement of oscillation frequency
When the S-35190A is turned on, the internal power-on detector operates and a signal of 1 Hz is output from the INT pin
to select the crystal oscillator and optimize the Cg value. Turn the power on and measure the signal with a frequency
counter following the circuit configuration shown in Figure 46.
If 1 Hz signal is not output, the power-on detector does not operate normally. Turn off the power and then turn it on
again. For how to apply power, refer to “ Power-on Detector 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 expression).
10–6 (1 ppm) × 60 seconds × 60 minutes × 24 hours × 30 days = 2.592 seconds
INT
CS
SIO
SCK S-35190A
VDD
XOUT
XIN
VSS
C
g
10 kΩ
10 kΩ
10 kΩ
Open
Frequency
counter
Figure 46 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.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
38
3. Adjustment of oscillation frequency
(1) Adjustment by setting Cg
Matching of the crystal oscillator with the nominal frequency must be performed with the stray capacitance on the
board included. Select a crystal oscillator and optimize the Cg value in accordance with the flowchart below.
START
END
Set to center
of variable
capacitance
*3
Select a crystal
oscillator
*1
Variable
capacitance
Change C
g
Optimal
value
*2
Frequency
C
g
in
specification
Set C
g
Make fine adjustment
of frequency using
variable capacitance
YES
NO
YES
NO
NO
YES
Trimmer capacitor
Fixed capacitor
NO
YES
*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 stray 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 47 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 to 25°C. Therefore, it is recommended to set the oscillator to operate slightly faster
at normal temperature.
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 39
Product Name Structure
S-35190A - xxxx G
Package name (abbreviation) and IC packing specification
J8T1 : 8-Pin SOP (JEDEC), Tape
T8T1 : 8-Pin TSSOP, Tape
I8T1 : SNT-8A, Tape
Product name
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 specifications of that product, nor does Seiko Instruments Inc. assume any responsibility for any infringement of
patents or copyrights by products that include this IC either in Japan or in other countries.
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
40
Characteristics (Typical Data)
(1) Standby current vs. VDD characteristics (2) Current consumption when 32.768 kHz is output
vs. VDD characteristics
Ta = 25°C, CL = 6 pF Ta = 25°C, CL = 6 pF
0 56
1.0
0.8
0.6
0.4
0.2
0
V
DD
[V]
I
DD1
[µ
A
]
1 23 4
0 5 6
1.0
0.8
0.6
0.4
0.2
0
V
DD
[V]
I
DD3
[µA]
123 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
30
25
20
15
10
5
0
I
DD2
[µ
]
200 400 600 800 1000
V
DD
= 5.0 V
V
DD
= 3.0 V
SCK frequency [kHz]
−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]
I
DD1
[µ
A
]
−25 0 25 50
V
DD
= 5.0 V
V
DD
= 3.0 V
(5) Standby current vs. 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
[µ
]
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
∆f/
f
[ppm]
024 6
C
g
[pF]
8 10
V
DD
= 5.0 V
V
DD
= 3.0 V
3-WIRE REAL-TIME CLOCK
Rev.2.4_00 S-35190A
Seiko Instruments Inc. 41
(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
∆f/
f
[ppm]
0 5 6
V
DD
[V]
1 23 4
20
0
−20
−40
−60
−80
−100
−120
−140
∆f/
f
[ppm]
−40 75 85
Ta [ °C]
−25 0 25 50
V
DD
= 5.0 V
V
DD
= 3.0 V
(9) Oscillation start time vs. Cg characteristics (10) Output current characteristics 1 (VOUT vs. IOL1)
Ta = 25°C
INT
pin, Ta
= 25°C
0
500
450
400
350
300
250
200
150
100
50
0
t
ST
A
[ms]
2 810
4 6
C
g
[pF]
V
DD
= 5.0 V
V
DD
= 3.0 V
0
50
40
30
20
10
0
I
OL1
[mA]
1 2 3 4
V
OUT
[V]
V
DD
= 5.0 V
V
DD
= 3.0 V
(11) Output current characteristics 2 (VOUT vs. IOL2) (12) CS pin input current characteristics
SIO pin, Ta = 25°C CS pin, Ta = 25°C
0
50
40
30
20
10
0
I
OL2
[mA]
0.5 1 1.5 2
V
OUT
[V]
2.5
V
DD
= 5.0 V
V
DD
= 3.0 V
800
700
600
500
400
300
200
100
0
I
IH
[µA]
05 6
V
IN
[V]
123 4
V
DD
= 5.0 V
V
DD
= 3.0 V
3-WIRE REAL-TIME CLOCK
S-35190A Rev.2.4_00
Seiko Instruments Inc.
42
(13) BLD detection, release voltage, VDDT (Min) vs.
Temperature characteristics
CL = 6 pF
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
V
DDT
(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
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
No.
TITLE
SCALE
UNIT mm
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
No.
TITLE
SCALE
UNIT mm
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
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.
•
The information described herein is subject to change without notice.
• Seiko Instruments Inc. is not responsible for any problems caused by circuits or diagrams described herein
whose related industrial properties, patents, or other rights belong to third parties. The application circuit
examples explain typical applications of the products, and do not guarantee the success of any specific
mass-production design.
• When the products described herein are regulated products subject to the Wassenaar Arrangement or other
agreements, they may not be exported without authorization from the appropriate governmental authority.
• Use of the information described herein for other purposes and/or reproduction or copying without the
express permission of Seiko Instruments Inc. is strictly prohibited.
• The products described herein cannot be used as part of any device or equipment affecting the human
body, such as exercise equipment, medical equipment, security systems, gas equipment, or any apparatus
installed in airplanes and other vehicles, without prior written permission of Seiko Instruments Inc.
• Although Seiko Instruments Inc. exerts the greatest possible effort to ensure high quality and reliability, the
failure or malfunction of semiconductor products may occur. The user of these products should therefore
give thorough consideration to safety design, including redundancy, fire-prevention measures, and
malfunction prevention, to prevent any accidents, fires, or community damage that may ensue.