Document Outline
- S-35L12A
- Cover
- Features
- Applications
- Package
- Block Diagram
- Product Code Structure
- Pin Assignment
- Description of Pins
- Absolute Maximum Ratings
- Recommended Operating Conditions
- Oscillation Characteristics
- DC Electrical Characteristics
- AC Electrical Characteristics
- Timing Chart
- Description of Operation
- Samples of Application Circuits .
- Adjustment of Oscillating Frequency
- Precautions
- Characteristics (Reference Data)
- Package Drawing
Rev. 1.3
_00
REAL-TIME CLOCK
S-35L12A
Seiko
Instruments
Inc.
1
S-35L12A is a CMOS real-time clock IC, which is designed to
transfer or set each data of a clock and calendar as requested
by CPU.
The S-35L12A is interfaced with CPU via three wires. Two
systems of an interrupt/alarm function and 32 kHz-fixed clock
output make it easy to develop and process software at the
side of a host computer. It also works on lower power with the
oscillating circuit operated at a constant voltage.
Features
Low power consumption
:0.55
A typ. (V
DD
=3.0 V, Ta=25C)
Wide area of operating voltage :1.3 to 3.6 V
(1.65 to 3.6 V with the power voltage detection circuit built-in)
BCD input/output of year, month, day, day of a week, hour, minute and second
CPU interface via three wires
Auto calender till the year of 2,099
(automatic leap year arithmetic feature included)
Built-in power voltage detecting circuit
Built-in constant voltage circuit
Built-in flag generating circuit on power on/off
Built-in alarm interrupter (two systems)
32 kHz-fixed clock output
Steady-state interrupt frequency/duty setting feature
Built-in 32 kHz crystal oscillating circuit (Internal Cd, External Cg)
Applications
Cellular phone
PHS
A variety of pagers
TV set and VCR
Camera
Package
10-Pin SSOP (pin pitch : 0.5 mm) (Package drawing code : FS010-A)
Die
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
2
Seiko Instruments Inc.
Block Diagram
INT1 Register
Status register
Oscillating
circuit
SCK
SIO
Timing
generation
Power
voltage
detecting
circuit
Constant
voltage
circuit
F32K
VDD
VSS
Comparator 1
Second Minute
Hour
Day of
week
Day
Month
Year
Shift register
INT1
XIN
XOUT
Clock
generating
circuit
Comparator 2
INT2
INT2 Register
Clock
generating
circuit
CS
Serial
Interface
Figure 1
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
3
Product Code Structure
S-35L12AE
xx
Package name (abbreviation)
FS: 10-Pin SSOP10
CA: Die
Description (fixed)
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
4
Seiko Instruments Inc.
Pin Assignment
(1) Package: S-35L12AEFS
INT1
10-pin SSOP
Top view
XOUT
VSS
F32k
8
7
6
10
9
3
4
5
1
2
SIO
VDD
SCK
INT2
CS
XIN
Figure 2
(2) Die : S-35L12AECA
XOUT
SDA
VDD
SCK
F32K
INT1
XIN
VSS
S-35L12A
0
X
Y
INT2
CS
Remark
Die size : 1.94
1.58 mm
Sizes shown are for design purposes only.
The corners of the die shrink by approximately 30
m after dicing.
Pad size : 100
100 m
Chip rear area potential : VSS
Pad Coordinates
Symbol
X-Coordinate Y-Coordinate Symbol
X-Coordinate Y-Coordinate
INT1
-811 631
VDD
811 631
XIN
-811 330
SIO
811 393
XOUT
-811 29
SCK
811
-29
VSS
-811
-375 CS 811 -209
F32k
-811
-631 INT2 811
-631
Figure 3
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
5
Description of Pins
Table 1
Pin No.
Symbol
Description
Configuration
1
INT1
Alarm interrupt 1 output pin.
Depending on the mode set by the INT1
register and status register, it outputs low or
Clock when time is reached. It is disabled by
rewriting the status register.
Nch open drain output (No
protective diode at the side
of VDD)
2 XIN
3 XOUT
Crystal oscillator connect pin (32,768 Hz)
(Internal Cd, External Cg)
-
4
VSS
Negative power supply pin (GND)
-
5
F32K
32,768 Hz clock output pin
Nch open drain output (No
protective diode at the side
of VDD)
6
INT2
Alarm interrupt 2 output pin.
Depending on the mode set by the INT2
register and status register, it outputs low or
Clock when time is reached. It is disabled by
rewriting the status register.
Nch open drain output (No
protective diode at the side
of VDD)
7
CS
Chip select input pin.
During "H" : The SIO pin allows data
input/output.
The SCK pin allows data input.
During "L" : The SIO pin is in the Hi-Z state.
The SCK pin is in the input-
disabled state.
CMOS input (internal pull-
down resistance. No
protective diode at the side
of VDD)
8
SCK
Serial clock input pin.
The input/output of data from the SIO pin is
performed in synchronization with this clock.
However, the clock is not accepted while the
CS pin is "L".
CMOS input (No protective
diode at the side of VDD)
9
SIO
Serial data input/output pin.
It is normally in the Hi-Z state while the CS
pin is "L". When the CS pin changes from "L"
to "H", the SIO pin is set to an input pin. It will
be set to an input or output pin, depending on
an subsequently input command.
Nch open drain output (No
protective diode at the side
of VDD)
CMOS input
10
VDD
Positive power supply pin.
-
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
6
Seiko Instruments Inc.
Absolute Maximum Ratings
Table 2
Item
Symbol
Applicable pin, conditions
Rating
Unit
Power voltage
V
DD
-
V
SS
-0.3 to V
SS
+4.0 V
Input voltage
V
IN
Applied
to
SCK,SIO V
SS
-0.3 to V
SS
+4.0 V
Output voltage
V
OUT
Applied
to
SIO,INT1,
INT2 V
SS
-0.3 to V
SS
+4.0 V
Storage temperature
T
stg
-
-55 to +125
C
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 Operating Conditions
Table 3
Item
Symbol
Condition Min.
Typ.
Max.
Unit
Power voltage
V
DD
- 1.3
3.0
3.6
V
Operating temperature
T
opr
-
-20
+25
+70
C
Oscillation Characteristics
Table 4
(Unless otherwise specified : Ta
=25C, V
DD
=3 V, DS-VT-200 (crystal oscillator, C
L
=6 pF, 32,768 Hz) manufactured by SII Quartz Techno Ltd.)
Item Symbol
Condition
Min.
Typ.
Max.
Unit
Oscillation start voltage
V
STA
Within ten seconds
1.3
- 3.6 V
Oscillation start time
T
STA
V
DD
=3 V
-
- 1 s
IC-to-IC frequency diversity
IC
-
-10
-
+10 ppm
Frequency voltage diversity
V V
DD
=1.3 to 3.6 V
-3
-
+3 ppm/V
Input capacity
C
g
Applied to the XIN pin
3
- 35 pF
Output capacity
C
d
Applied to the XOUT pin
- 12 - pF
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
7
DC Electrical Characteristics
Table 5 DC characteristics (3 V)
(Unless otherwise specified : Ta
=25C, V
DD
=3 V, DS-VT-200 (crystal oscillator, C
L
=6 pF, 32,768 Hz) manufactured by SII Quartz Techno Ltd.)
Item Symbol
Applicable
pin
Condition Min.
Typ.
Max.
Unit
Operating voltage range
V
DD
-
Ta
= -20 to +70C 1.3
3.0
3.6
V
Current consumption 1
I
DD1
-
During no communications
- 0.55
0.85
A
Current consumption 2
I
DD2
-
During communications
(SCK
=100 kHz)
- 12 20 A
Input leak current 1
I
IZH
SCK,
SIO
V
IN
=V
DD
-0.5
- 0.5 A
Input leak current 2
I
IZL
SCK,
SIO
V
IN
=V
SS
-0.5
- 0.5 A
Input current 1
I
IL1
CS
V
IN
=3.6 V
2
6
20
A
Input current 2
I
IL2
CS
V
IN
=0.4 V
40
110
300
A
Output leak current1
I
OZH
INT1, INT2 SIO
V
OUT
=V
DD
-0.5
- 0.5 A
Output leak current2
I
OZL
INT1, INT2 SIO
V
OUT
=V
SS
-0.5
- 0.5 A
Input voltage 1
V
IH
SIO,
SCK,
CS
- 0.8V
DD
-
- V
Input voltage 2
V
IL
SIO,
SCK,
CS
-
-
- 0.2V
DD
V
Output current 1
I
OL1
INT1,
INT2
V
OUT
=0.4 V
1.5
2.5
- mA
Output current 2
I
OL2
SIO
V
OUT
=0.4 V
5
10
- mA
Power voltage detection
voltage 1
V
DET1
-
Ta
=+25C
- 1.45 - V
Power voltage detection
voltage 2
V
DET2
-
Ta
= -20 to +70C 1.15
- 1.65 V
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
8
Seiko Instruments Inc.
AC Electrical Characteristics
(S-35L12A, R
L
=10 K, C
L
=80 pF)
Table 6 AC characteristics 1
Conditions :
V
DD
=1.3 V to 3.6 V, Ta=
-20 to 70C
Input; V
IH
=0.8
V
DD
, V
IL
=0.2
V
DD
Output;
V
OH
=0.8
V
DD
, V
OL
=0.2
V
DD
(V
CC
=3.0 V)
Item Symbol
Min.
Typ.
Max.
Unit
Clock pulse width
t
SCK
5
- 250000 s
Setup time before CS rising
t
DS
1
-
-
s
Hold time after CS rising
t
CSH
1
-
-
s
Input data setup time
t
ISU
1
-
-
s
Input data hold time
t
IHO
1
-
-
s
Output data definition time
t
ACC
-
- 3.5 s
Setup time before CS falling
t
CSS
1
-
-
s
Hold time after CS falling
t
DH
1
-
-
s
Input rising/falling time
t
R
, t
F
-
- 0.1 s
Caution Since the output form of the SIO pin is Nch open drain output, the rising time of
t
ACC
is determined by the values of load resistance (R
L
) and load capacity (C
L
)
outside the IC. Use this as a reference value.
Table 7 AC characteristics 2
Conditions :
V
DD
=3.0
0.3 V, Ta=-20 to 70C
Input; V
IH
=0.8
V
DD
, V
IL
=0.2
V
DD
Output;
V
OH
=0.8
V
CC
, V
OL
=0.2
V
CC
(V
CC
=3.0 V)
Item Symbol
Min.
Typ.
Max.
Unit
Clock pulse width
t
SCK
1
- 250000 s
Setup time before CS rising
t
DS
0.2
-
-
s
Hold time after CS rising
t
CSH
0.2
-
-
s
Input data setup time
t
ISU
0.2
-
-
s
Input data hold time
t
IHO
0.2
-
-
s
Output data definition time
t
ACC
-
- 1.0 s
Setup time before CS falling
t
CSS
0.2
-
-
s
Hold time after CS falling
t
DH
0.2
-
-
s
Input rising/falling time
t
R
, t
F
-
- 0.05 s
Caution Since the output form of the SIO pin is Nch open drain output, the rising time of
t
ACC
is determined by the values of load resistance (R
L
) and load capacity (C
L
)
outside the IC. Use this as a reference value.
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
9
Timing Chart
t
CSH
t
DH
t
CSS
t
DS
CS
SCK
SIO
Figure 4
Figure 6
80
%
80
%
20
%
20
%
50
%
20
%
80
%
20
%
20
%
80
%
t
ACC
t
SCK
t
SCK
t
R,
t
F
t
F
t
R
t
ISU
SCK
Input Data
t
IHO
50
%
SCK
Output Data
Figure 5
t
DS
t
DH
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
10
Seiko Instruments Inc.
Description
of
Operation
1. Serial
interface
S-35L12A receives various commands via 3-wire serial interface to read/write data. This section covers the
transfer methods of this product.
1.1 Communication data configuration
After turning the CS pin to "H", send a 4-bit fixed code "0110" and succeedingly transfer the command of
a 3-bit length and read/write command of a 1-bit length.
Command
0
1
1
0
C2
C1
C0
R/W
Fixed code
MSB
LSB
Read/Write bit
Figure 7 Communication data
1.2 Command configuration
There are eight types of commands which read from and write to various registers. The table below lists
them. Any command that is not listed in the table provides no operation.
Table 8 Command list
C2 C1 C0
Description
0
0
0
Reset (00 (year), 01 (month), 01 (day), 0 (day of week),
00 (minute), 00 (second))
*1
0 0 1
Status
register
access
0
1
0
Real-time data access 1 (year data to)
0
1
1
Real-time data access 2 (hour data to)
1
0
0
Alarm time/frequency duty setting 1 (for INT1 pin)
1
0
1
Alarm time/frequency duty setting 2 (for INT2 pin)
1 1 0
Test
mode
start
*2
1 1 1
Test
mode
end
*2
*1. Don't care the R/W bit of this command.
*2. This command is access-disabled due to specific use for the IC test.
1.3 Data reading
When you input data from the SIO pin in synchronization with the falling of the SCK pin after turning the
CS pin to "H", the data is included in the S-35L12A at the eighth rising of the SCK clock and the state of
data reading is reached when the R/W bit has "1". The state leads to output of data corresponding each
command in synchronization with the falling of subsequent SCK clock input.
Remark
When the number of SCK clocks is less than eight, the state of clock waiting is reached and no
processing is done.
When SCK clocks are more than required, they are processed in order from the first and the
clocks other than those required are ignored.
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
11
SCK
SCK
SCK
TEST
64
9
1
1
0
1
0
0
1
1
0
X
Output mode switching
(1) Real-time data reading 1
9
1
(3) Status register reading
Year data
Second data
1
1
0
0
0
1
1
0
X
Output mode switching
Status data
Input mode switching
LSB
MSB
TEST
32
9
1
1
1
1
0
0
1
1
0
X
Output mode switching
(2) Real-time data reading 2
Hour data
Second data
LSB
MSB
LSB
MSB
LSB
MSB
LSB
MSB
Input mode switching
Input mode switching
Command
Command
Command
LSB
MSB
LSB
MSB
LSB
MSB
POWER
SIO
CS
SIO
CS
SIO
CS
Figure 8 Read communication
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
12
Seiko Instruments Inc.
1.4 Data
writing
When you input data from the SIO pin in synchronization with the falling of the SCK pin after turning the
CS pin to "H", the data is included into the inside of S-35L12A at the eighth rising of the SCK clock and the
state of data writing is reached when the R/W bit has "0". In the state, the data is written to registers
according each command in synchronization with the falling of subsequent SCK clock input.
SCK
SCK
SCK
TEST
64
9
1
0
0
1
0
0
1
1
0
X
(1) Real-time data writing 1
9
1
(3) Status register writing
Year data
Second data
0
1
0
0
0
1
1
0
X
Status data
LSB
MSB
TEST
32
9
1
0
1
1
0
0
1
1
0
X
(2) Real-time data writing 2
Hour data
Second data
LSB
MSB
LSB
MSB
LSB
MSB
LSB
MSB
Command
Command
Command
LSB
MSB
LSB
MSB
LSB
MSB
POWER
SIO
CS
SIO
CS
SIO
CS
Figure 9 Write communication
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
13
2. Register configuration
2.1 Real-time data register
The real-time data register is a 56-bit register which stores the BCD code of the data of year, month,
day, day of week, hour, minute and second. Any read/write operation performed by the real-time data
access command sends or receives the data from LSB on the first digit of the year data.
Y80 Y40 Y20 Y10 Y8
Y4
Y2
Y1
MSB
LSB
Year data (00 to 99)
YF
0
0
M10 M8
M4
M2
M1
MSB
LSB
Month data (01 to 12)
Sets the lower two digits of the year (00 to 99)
and links together with the auto calendar feature
until 2,099.
The count value is automatically changed by the
auto calender feature:
1, 3, 5, 7, 8, 10, 12: 1 to 31
4, 6, 9, 11: 1 to 30
2 (leap year): 1 to 29
2 (common year): 1 to 28
AM/
PM
0
0
D20 D10 D8
D4
D2
D1
MSB
LSB
Day data (01 to 31)
0
0
0
0
0
W4
W2
W1
MSB
LSB
Day of week data (00 to 06)
A septenary counter. Set it so that it
corresponds to the day of the week.
0
H20 H10 H8
H4
H2
H1
MSB
LSB
Hour data (00 to 23 or 00 to 11)
0
MSB
LSB
Minute data (00 to 59)
TEST S40 S20 S10 S8
S4
S2
S1
MSB
LSB
Second data (00 to 59) and test flag
m10 m8
m4
m2
m1
AM/PM : For 12-hour expression, 0:AM and 1:PM.
For 24-hour expression, this flag has no
meaning but either 0 or 1 must be written.
TEST : Turns to "1" during the test mode.
m20
m40
Year Flag (YF)
The count value is set to 0 when changing date from 59:
59:23, Dec. 31, 1999 to 00: 00:00, Jan. 1, 2000. At
reset, it is set to 1. Set the year data to 0 for 2000s and
for 1900s because it is not automatically set or reset.
Figure 10
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
14
Seiko Instruments Inc.
2.2 Status
register
The status register is an 8-bit register which allows you to display and set various modes. The POWER
flag is read-only and others are read/write-enabled.
B7
LSB
POWER
12/24
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
INT1AE
INT2AE
INT2ME
INT1ME
MSB
B6
B5
B4
B3
B2
B1
B0
INT2FE
INT1FE
Figure 11
B7:POWER
This flag turns to "1" if the power voltage detecting circuit operates during power-on
or changes in power voltage (below V
DET
). Once turning to "1", this flag does not
turns back to "0" even when the power voltage reaches or exceeds the detection
voltage. When the flag is "1", you must send the reset command (or status register
read command) and turn it to "0". It is a read-only flag.
B6:12/24
This flag is used to set 12-hour or 24-hour expression.
0 : 12-hour expression
1 : 24-hour expression
B5:INT1AE, B4:INT2AE
This flag is used to choose the state of INT1 pin (or INT2 pin) output with alarm
interrupt output set. Enable this flag after setting alarm time that forms a meeting
condition in the INT1 register (or INT2 register):
0 : Alarm interrupt output is disabled.
1 : Alarm interrupt output is enabled.
B3:INT1ME, B2:INT2ME
This flag is used to make the output of the INT1 pin (or INT2 pin) per-minute edge
interrupt or per-minute steady interrupt. To make the output per-minute steady
interrupt, set "1" at INT1ME and INT1FE (or INT2ME and INT2FE).
0 : Alarm interrupt or selected frequency steady interrupt output
1 : Per-minute edge interrupt or per-minute steady interrupt output
B1:INT1FE, B0:INT2FE
This flag is used to make the output of the INT1 pin (or INT2 pin) per-minute steady
interrupt output (a period of one minute, 50% of duty) or selected frequency steady
interrupt. Note that the INT1 register (INT2 register) is considered as the data of
frequency/duty if selected frequency steady interrupt is chosen.
0 : Alarm interrupt or per-minute edge interrupt output
1 : Per-minute steady interrupt or selected frequency steady
interrupt output
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
15
2.3 Alarm time/Frequency duty setting register
There are two types of alarm time/frequency duty setting registers, 16-bit registers, which set alarm time
or frequency duty. They are switched by INTxAE or INTxFE register. AM/PM flag to be set must be in
accordance with 12-hour or 24-hour expression. If AM/PM flag is not rightly then set hour data is not met to
alarm data. The alarm time/frequency duty setting register is a write-only register.
(1) When INTxAE
=
=
=
= 1
AM/
PM
0
H8
H4
H2
H1
MSB
LSB
0
m8
m4
m2
m1
MSB
LSB
H20
H10
m10
m20
m40
INT1 register
AM/
PM
0
H8
H4
H2
H1
MSB
LSB
0
m8
m4
m2
m1
MSB
LSB
H20
H10
m10
m20
m40
INT2 register
Figure 12 INT1 register (alarm)
Figure 13 INT2 register (alarm)
INT1 and INT2 registers are considered as alarm time data. Having the same configuration as the
time and minutes registers of real-time data register configuration, they represent hours and minutes with
BCD codes. When setting them, do not set any none-existent day. Data to be set must be in accordance
with 12-hour or 24-hour expression that is set at the status register.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
16
Seiko Instruments Inc.
(2) When INTxFE
=
=
=
= 1
INT1 and INT2 registers are considered as frequency duty data. By turning each bit of the registers to
"1", a frequency corresponding to each bit is chosen in an ANDed form.
f0
MSB
LSB
INT1 register
MSB
LSB
f1
f2
f3
f4
f5
f6
f7
f8
f9
f10
f11
f12
f13
f14
f15
f0
MSB
LSB
INT2 register
MSB
LSB
f1
f2
f3
f4
f5
f6
f7
f8
f9
f10
f11
f12
f13
f14
f15
f0 32768
Hz f4 2048
Hz f8 128
Hz f12 8
Hz
f1 16384
Hz f5 1024
Hz f9 64
Hz f13 4
Hz
f2 8192
Hz f6 512
Hz f10 32
Hz f14 2
Hz
f3 4096
Hz f7 256
Hz f11 16
Hz f15 1
Hz
Figure 14 INT1 and INT2 registers (frequency/duty)
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
17
32 kHz
Example
If f15 to f0
= 000A H
16 kHz
8 kHz
4 kHz
2 kHz
Set to selected frequency steady
interrupt output
INT1 or INT2
terminal output
Figure 15 Clock output
2.4 Test flag
The test flag is a 1-bit register which is assigned to MSB of the second data of the real-time data
register. If a transferred data is considered as the test mode starting command due to the receiving of the
test mode starting command or noises, "1" is set. When "1" is set, you must send the test mode ending
command or reset command.
3. Initialization
Note that S-35L12A has different initializing operations, depending on states.
3.1 When power
is turned on
When power is turned on, the status register is set to "82h" and the INT1 register to "8000h" by the
power-on detecting circuit. In other words, "1" is set at the bit 7 (POWER flag) of the status register and the
clock of 1 Hz is output from the INT1 pin. This is provided to adjust oscillating frequencies. In normal use,
the reset command must be sent when power is turned on.
Real-time data register : 00 (year), 01 (month), 01 (day), 0 (day of week), 00 (hour), 00
(minute), 00 (second) (year flag: "1")
Status register
: "82h"
INT1 register
: "8000h"
INT2 register
: "0000h"
3.2 When the power voltage detecting circuits operates
The power voltage detecting circuit included in S-35L12A operates and sets "1" at the bit 7 (POWER
flag) of the internal status register when power is turned on or power voltage is reduced. Once "1" is set, it
is held even after the power voltage gets equal to or higher than the detection voltage, i.e., power voltage
detector threshold. When the flag has "1", you must send the reset command from CPU and initialize the
flag. At this point, other registers do not change, however, if the POWER flag has "0" during the power-on
reset of CPU (S-35L12A does not reach any indefinite area during backup), you do not have to send the
reset command.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
18
Seiko Instruments Inc.
3.3 When the reset command is received
When the reset command is received, each register turns as follows:
Real-time data register : 00 (year), 01 (month), 01 (day), 0 (day of week), 00 (hour), 00
(minute), 00 (second) (year flag : "1")
Status register
: "00h"
INT1 register
: "0000h"
INT2 register
: "000h"
0
1
1
0
R
/
W
M
S
B
SIO LINE
0
0
1
L
S
B
1
command
status read command
V
DD
POWER
flag
0
1
1
0
R
/
W
M
S
B
SIO LINE
0
0
1
L
S
B
1
command
V
DD
POWER
flag
0
1
1
0
R
/
W
M
S
B
0
0
L
S
B
1
1
0
0
0
0
0
POWER flag
0
Don't care
backup state (S-35L12A does not reach any indefinite
0
1
1
0
R
/
W
M
S
B
0
1
L
S
B
0
0
0
0
0
0
0
POWER flag
0
CPU down
reset command
status data
1
1
0
data
0
data
status read command
status data
command
command
real-time data read
M
S
B
M
S
B
Figure 16 Initializing
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
19
4. Processing of none-existent data and end-of-month
When writing real-time data, validate it and treat any invalid data and end-of-month correction.
[None-existent data processing]
Table 9
Register Normal
data
Error
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 week data
0 to 6
7
0
Hour data
*1
(24-hour)
(12-hour)
0 to 23
0 to 11
24 to 29, 3X, XA to XF
12 to 19, XA to XF
00
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.
For 12-hour expression, write the AM/PM flag .
The AM/PM flag is ignored in 24-hour expression, but "0" for 0 to 11 o'clock and "1" for 12 to 23
o'clock are read in a read operation.
*2.
None-existent data processing for second data is performed by a carry pulse one second after
the end of writing. At this point, the carry pulse is sent to the minute counter.
[End-of-month correction]
Any none-existent day is corrected to the first day of the next month. For example, February 30 is
changed to March 1. Leap-year correction is also performed here.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
20
Seiko Instruments Inc.
5. Interrupt
There are different five output formats from the INT1 and INT2 pin, which are chosen by the INTxAE, INTxME
and INTxFE bits of the status register (x:1 or 2).
(1) Alarm interrupt output
Alarm interrupt is enabled by setting hour and minute data to the INT1 register (or INT2 register) and
turning the status register's INT1AE to "1" and INT1ME and INT1FE to "0" (or INT2AE to "1" and INT2ME
and INT2FE to "0"). When set hour data is met, "K" is output from the INT1 pin (or INT2 pin). Since the
output is held, rewrite INT1AE (or INT2AE) of the status register to "0" through serial communication to
turn the output to high (OFF state).
The coincidence signal is set when minute changes from 59 seconds to 0 second and outputs the "L"
signal from the INT1 pin (or INT2 pin). When you perform disable or enable communication within the
coincidence period (1 minute), pay attention that INT1 pin (or INT2 pin) remains "High" level (OFF state).
(2) Selected frequency steady interrupt output
When you set frequency/duty data to the INT1 register (or INT2 register) and turn the status register's
INT1ME to "0" and INT1FE to "1" (or INT2ME to "0" and INT2FE to "1"), clock set at the INT1 register (or
INT2 register) is output from the INT1 pin (or INT2 pin).
(3) Per-minute edge interrupt output
When a first minute carry is performed after the status register's INT1ME is set with "1" and INT1FE
with "0" (or INT2ME with "1" and INT2FE with "0"), "L" is output from the INT1 pin (or INT2 pin). Since the
output is held, rewrite INT1AE, INT1ME and INT1FE (or INT2AE, INT1ME and INT2FE) of the status
register to "0" through serial communication to turn the output to high (OFF state). When you perform
disable or enable communication while the minute carry processing signal is being retained (for 123
s),
"L" signal is output from the INT1 pin (or INT2 pin) again.
(4) Per-minute steady interrupt output
When a first minute carry is performed after the status register's INT1ME and INT1FE are set with "1"
(or INT2ME and INT2FE with "1"), clock is output from the INT1 pin (or INT2 pin) with a period of one
minute (50% duty).
When you perform disable or enable communication while the INT1 pin (or INT2 pin) is at "L," "L"
signal is output from the INT1 pin (or INT2 pin) again.
Caution 1. If changing an output mode, give care to the state of the INT1and INT2 registers and
output.
2. If per-minute edge interrupt output or per-minute steady interrupt output is chosen, the
INT1 and INT2 registers have no meaning.
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
21
Table 10 Interrupt description
NO. INT1AE INT1ME INT1FE
Description
0
0
0
0
INT1 pin output disabled (No interrupt output)
1
*
0
1
Selected frequency steady interrupt output from the
INT1 pin
2
*
1
0
Per-minute edge interrupt output from the INT1 pin
3
*
1
1
Per-minute steady interrupt output from INT1 pin
4
1
0
0
Alarm interrupt output from INT1 pin
NO. INT2AE INT2ME INT2FE
Description
5
0
0
0
INT2 pin output disabled (No interrupt output)
6
*
0
1
Selected frequency steady interrupt output from the
INT2 pin
7
*
1
0
Per-minute edge interrupt output from the INT2 pin
8
*
1
1
Per-minute steady interrupt output from INT2 pin
9
1
0
0
Alarm interrupt output from INT2 pin
Note * Don't care (both 0 and 1 are available)
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
22
Seiko Instruments Inc.
(1) Alarm
interrupt
output
hour minute
INTxAE
INTx pin
INTxME
=INTxFE=0
OFF
Once the alarm time is reset, no "L"
signal generates even when you enable
within the conincidence time.
Alarm time corresponds
Alarm time corresponds
Change by program
h (n-2)
h (n-1)
h (n)
h (n+1)
K (m-1)
K (m)
K (m+1)
(2) Selected frequency steady interrupt output
INTxFE
INTx pin
INTxAE
=INTxME=0
Free run output starts
Change by program
OFF
(3) Per-minute edge interrupt output
INTxME
NTx pin
INTxAE
=INTxFE=0
OFF
Minute-carry processing
Change by program
"L" signal is output again in case of
123
s or less
Minute-carry processing
(4) Per-minute steady interrupt output
30 s
INTxFE,INTxME
INTx pin
INTxAE
=0
Minute-carry
processing
Minute-carry
processing
Change by program (OFF)
30 s
30 s
30 s
30 s
30 s
30 s
30 s
Minute-carry
processing
Minute-carry
processing
Minute-carry
processing
"L" signal is output again in case of 123
s or less.
"H" signal is output in case of 123
s or more.
"L" signal is output by the next minute-carry processing.
30 s
(5) During power-on detecting circuit operation
INTxFE
INT2 pin is in
OFF state
INT1 pin
INTxAE
=INTxME=0
Change by the reset command
OFF
0.5 s
0.5 s
Figure 17 Output mode
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
23
6. Power voltage detecting circuit
S-35L12A has an internal power voltage detecting circuit. This circuit gives sampling movement for only 15.6
ms once a second. If the power voltage decreases below the detection voltage (V
DET
), the BLD latch circuit
latches the "H" level, and sampling movement stops. Only when subsequent communication is of the status
read command, the output of the latch circuit is transferred to the sift register and the sampling movement is
resumed. Decrease in power voltage can be monitored by reading the POWER flag. That is to say, once
decrease in power voltage is detected, any detecting operation is not performed and "H" is held unless you
perform initialization or send the status read command.
Caution When power voltage is increased and the first read operation is performed after decrease in
power voltage occurs and the latch circuit latches "H", "1" can be read on the POWER flag,
however, if the next read operation is performed after the sampling of the detecting circuit, the
POWER flag is reset since sampling is subsequently allowed. See the timing diagram below.
Latch circuit output
Sampling pulse
(0)
1s
1s
Stop
Stop
Stop
(1)
(1)
(1)
(1)
(1)
(1)
(0)
POWER flag
V
DD
V
DET
Communication
Latch circuit
output
Sampling pulse
1 s
1 s
(1)
(0)
Communication
POWER flag
Carry pulse
[Timing of sampling pulse]
0.5 s
0.5 s
7.8 ms
Carry-up timing
1 Hz
15.6 ms
Latch timing
Sampling pulse
(1)
(0)
V
DET
V
DD
Stop
Stop
Stop
Stop
Figure 18 Timing of the power voltage detecting circuit
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
24
Seiko Instruments Inc.
7. Example of software treatment
(1) Initialization flow at power-on
NO
YES
START
END
POWER
1
*1.
If S-35L12A is back-up and power is turned on only
on the CPU side, the reset command does not need
transferring.
*2.
If conditions are no good (e.g., noise)
and probable
changes in commands occurs via
serial
communications, it is recommended to
make sure the
TEST
flag.
*3.
The test ending command may be used alternately.
Power on
Reset command
transfer
NO
YES
TEST
=1
Reset command
transfer
Status register setting
command transfer
Real-time data setting
command transfer
INTx register setting
command transfer
*1
*2
*3
Figure 19 Initialization flow
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
25
Samples of Application Circuits
Vcc
XOUT
XIN
S-35L12A
SIO
VSS
VDD
SCK
VSS
VCC
External CPU
INT2
INT1
CS
System
power
C
g
Due to the I/O pin with no protective diode on the VDD side, the relation of VCC
VDD has no problem
but give great care to the standard. Make communications after the system power is turned on and a stable
state is obtained.
Figure 20 Application circuit 1
VSS
VCC
External CPU
Power
switching
circuit
XOUT
XIN
S-35L12A
SIO
VSS
VDD
SCK
INT2
INT1
CS
System
power
C
g
Make communications after the system power is turned on and a stable state is obtained.
Figure 21 Application circuit 2
Caution The application circuits above do not guarantee proper operation.
Evaluate in the actual application to determine the correct constants
.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
26
Seiko Instruments Inc.
Adjustment of Oscillating Frequency
1. Configuration of the oscillating circuit
Since crystal oscillation is sensitive to external noises (clock accuracy is affected), the following measures are
essential for optimizing your oscillating circuit configuration:
(1) Place S-35L12A, crystal oscillator and external capacitor (C
g
) as close to each other as possible.
(2) Make high 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 oscillating circuit.
XIN
XOUT
C
g
S-35L12A
C
d
R
d
R
f
Crystal oscillator:32.768 Hz
C
L
=6 pF
C
g
=3 to 35 pF
Oscillating circuit internal constant standard
values:
R
f
=20 M
R
d
=220 k
C
d
=12 pF
Figure 22 Connection diagram
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
27
2. Measurement of oscillating frequencies
When power is turned on, S-35L12A has the internal power-on detecting circuit operating and outputs a
signal of 1 Hz from the INT1 pin to select the crystal oscillator and optimize the C
g
value. Turn power on and
measure the signal with a frequency counter following the circuit configuration shown in Figure 23.
Remark If the error range is
1 ppm in relation to 1 Hz, time is shifted by approximately 2.6 seconds a month
(as calculated using the following expression)
10
-6
(1ppm)
60 seconds 60 minutes 24 hours 30 days = 2.592 seconds
Open
Frequency
counter
VDD
XIN
XOUT
SIO
CS
INT1
VSS
SCK
C
g
S-35L12A
Open
INT2
Figure 23 Connection diagram
Caution 1. Use a high-accuracy frequency counter (1 ppm order).
2. Since the 1 Hz signal continues to be output, you must send the reset command in
normal operation.
3. Determine
C
g
with its frequency slow/fast range property referred.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
28
Seiko Instruments Inc.
3. Adjustment of oscillating frequencies
Matching of a crystal oscillator with the nominal frequency must be performed with parasitic capacitance on
the board included. Select a crystal oscillator and optimize the C
g
value in accordance with the flow chart below.
YES
NO
YES
START
Variable
capacity
Select a crystal oscillator.
NO
Is C
g
in the
specification ?
*1
*2
Set C
g
NO
Is it an
optimal
value ?
YES
Change C
g
END
Set to the center of
variable capacitor.
Does
the frequency
match ?
NO
YES
Make fine adjustment
of the frequency in
variable capacity.
*3
*3
<Trimer capacitor>
<Fixed capacitor>
Figure 24 Crystal oscillation setting flow
*1. For making matching adjustment of the IC with a crystal, contact an appropriate crystal maker to determine
the C
L
value (load capacity) and R
I
value (equivalent serial resistance). The C
L
value
= 6 pF and R
I
value
=
30 k
typ. are recommended values.
*2. C
g
value selection must be performed on the actual PCB since parasitic capacitance affects it. Select the C
g
value in a range from 3 pF to 35 pF. If the frequency does not match, change the C
L
value of the crystal.
*3. Adjust the rotation angle of the variable capacity so that the capacity value is somewhat smaller than the
center, and confirm the oscillating frequency and the center value of the variable capacity. This is done in
order to make the capacity of the center value smaller than one half of the actual capacity value because a
smaller capacity value makes a greater quantity of changes in a frequency. If the frequency does not match,
change the C
L
value of the crystal.
Caution 1. Oscillating frequencies are changed by ambient temperature and power voltage. Refer to
property samples.
2. The 32 kHz crystal oscillator operates slower at higher or lower ambient temperature than 20
to 25
C. Therefore, it is recommended to adjust or set the oscillator to operate somewhat
faster at normal temperature.
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
29
Precautions
Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in
electrostatic protection circuit.
SII claims no responsibility for any disputes arising out of or in connection with any infringement by products
including this IC of patents owned by a third party.
REAL-TIME CLOCK
S-35L12A
Rev.1.3
_00
30
Seiko Instruments Inc.
Characteristics (Reference Data)
(1) Standby current vs. C
g
(2) Standby current vs. V
DD
C
g
[pf]
0
10
20
30
C
g
[pf]
0
1
2
3
4
V
DD
[V]
0
0.25
0.5
0.75
1
Ta
=25C
I
DD1
[
A]
V
DD
=3 V
Ta
=25C
I
DD1
[
A]
0
0.25
0.5
0.75
1
1.25
1.5
C
g
=7 pf
(3) Operating current consumption vs. Input clock
(4) Standby current vs. temperature
(5) Oscillating frequency vs. C
g
(6) Oscillating frequency vs. V
DD
V
DD
[V]
0
2
4
6
0
5
10
15
Ta
=25C
-4
-2
0
2
4
f/f
[ppm]
Ta
=25C
f/f
[ppm]
-40
-20
0
20
40
60
V
DD
=3 V
SCK frequency
[kHz]
0
400
1,000
Ta [
C]
-40
0
40
80
Ta
=25C
0
10
20
30
40
50
I
DD2
[
A]
V
DD
=3 V
0
0.25
0.5
0.75
1
V
DD
=3 V, C
g
=7 pf
I
DD1
[
A]
REAL-TIME
CLOCK
Rev.1.3
_00
S-35L12A
Seiko
Instruments
Inc.
31
(8) Oscillation start time vs. C
g
Ta
=25C
(9) Output current 1 (V
OUT
vs. I
OL1
)
(7) Oscillating frequency vs. temperature
(10) Output current 2 (V
OUT
vs. I
OL2
)
C
g
[pf]
T
STA
[mS]
0
5
10
15
0
100
200
300
400
V
DD
=3 V
INT1 and INT2 pin, Ta
=25C
SIO pin, Ta
=25C
V
OUT
[V]
0
0.5
1
1.5
2
2.5
0
5
10
15
0
1
2
3
0
10
20
30
40
50
I
OL1
[mA]
V
DD
=3 V
V
DD
=3 V
V
OUT
[V]
I
OL2
[mA]
f/f
[ppm]
-50
0
50
100
-160
-120
-80
-40
20
Ta
=25C, V
DD
=3 V
Ta [
C]
No.
TITLE
SCALE
UNIT
mm
0.20.1
0.50
3.10.3
10
0.15
+0.1
-0.05
6
5
1
SSOP10-A-PKG Dimensions
Seiko Instruments Inc.
No. FS010-A-P-SD-1.1
FS010-A-P-SD-1.1
1
10
5
6
6.90.1
No.
TITLE
SCALE
UNIT
mm
8.00.1
1.550.05
1.40.1
(4.0)
1.550.05
4.00.1
2.00.05
0.30.05
Seiko Instruments Inc.
Feed direction
SSOP10-A-Carrier Tape
No. FS010-A-C-SD-1.1
FS010-A-C-SD-1.1
20.5
130.2
210.8
20.5
13.50.5
QTY.
2,000
No.
TITLE
SCALE
UNIT
mm
Seiko Instruments Inc.
Enlarged drawing in the central part
SSOP10-A-Reel
No. FS010-A-R-SD-1.1
FS010-A-R-SD-1.1
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.
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