Rev.1.3
_00
2-WIRE REAL-TIME CLOCK
S-35392A
The S-35392A is a CMOS 2-wire real-time clock IC which operates with the very low current
consumption and in the wide range of operation voltage. The operation voltage is 1.3 V to 5.5
V so that this IC can be used for various power supplies from main supply to backup battery.
Due to the 0.45
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 :
0.45
µA
typ. (V
DD
=
3.0 V, Ta
=
25°C)
Constant output of 32.768 kHz clock pulse (Nch open-drain output)
Wide range of operating voltage :
1.3 to 5.5 V
Built-in clock-correction function
Built-in free user register
2-wire (I
2
C-bus) 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 (C
d
built in, C
g
external)
Package : 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
Package Name
SNT-8A
Drawing Code
Package
PH008-A
Tape
PH008-A
Reel
PH008-A
Land
PH008-A
Seiko Instruments Inc.
1
2-WIRE REAL-TIME CLOCK
S-35392A
Pin Configuration
SNT-8A
Top view
32KO
XOUT
XIN
VSS
Figure 1
Rev.1.3
_00
1
2
3
4
8
7
6
5
VDD
SDA
SCL
INT2
Pin Configuration (S-35392A-I8T1G)
List of Pin
Table 1
Pin No.
1
2
3
4
5
6
7
8
Symbol
32KO
XOUT
XIN
VSS
INT2
Description
Pin for constant output of
32.768 kHz
Connection pin for crystal
oscillator
GND pin
Output pin for interrupt signal
2
I/O
Output
−
−
Output
Configuration
Nch open-drain output
(no protective diode at VDD)
−
−
SCL
SDA
VDD
Nch open-drain output
(no protective diode at VDD)
CMOS input
Input pin for serial clock
Input
(no protective diode at VDD)
Nch open-drain output
I/O pin for serial data
Bi-directional (no protective diode at VDD)
CMOS input
Pin for positive power supply
−
−
2
Seiko Instruments Inc.
Rev.1.3
_00
Pin Function
•
SDA (I/O for serial data) pin
2-WIRE REAL-TIME CLOCK
S-35392A
This pin is to data input/output for I
2
C-bus interface. This pin inputs/outputs data by synchronizing with a clock pulse
from the SCL pin. This pin has CMOS input and Nch open drain output. Generally in use, pull up this pin to the VDD
potential via a resistor, and connect it to any other device having open drain or open collector output with wired-OR
connection.
•
SCL (input for serial clock) pin
This pin is to input a clock pulse for I
2
C-bus interface. The SDA pin inputs/outputs data by synchronizing with the clock
pulse.
•
XIN, XOUT (crystal oscillator connect) pin
Connect a crystal oscillator between XIN and XOUT.
•
32KO (constant output of 32.768 kHz) pin
This is an output pin for 32.768 kHz. This pin constantly outputs a clock pulse after power-on.
•
INT2
(output for interrupt signal 2) pin
This pin outputs a signal of interrupt, or a clock pulse. By using the status register 2, users can select either of; alarm
interrupt, output of user-set frequency, per-minute edge interrupt or minute-periodical interrupt 1. 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 this VSS pin to GND.
Equivalent Circuits of I/O Pin
SDA
SCL
Figure 2
SDA Pin
32KO, INT2
Figure 3
SCL Pin
Figure 4
32KO Pin,
INT2
Pin
Seiko Instruments Inc.
3
2-WIRE REAL-TIME CLOCK
S-35392A
Block Diagram
Rev.1.3
_00
XIN
XOUT
Oscillator
Divider,
timing generator
INT1 register
INT1
controller
32KO
Clock correction register
Status register 1
Status register 2
Comparator 1
Real-time data register
Second Minute Hour
Day of
Day
the week
Month
Year
Comparator 2
Free register
Low power supply
voltage detector
Power-on
detector
Constant-
voltage circuit
VSS
INT2 register
INT2
controller
Serial
interface
SDA
SCL
INT2
VDD
Shift register
Figure 5
4
Seiko Instruments Inc.
Rev.1.3
_00
Absolute Maximum Ratings
Table 2
Parameter
Symbol
Applicable Pin
2-WIRE REAL-TIME CLOCK
S-35392A
Rating
Unit
Power supply voltage
V
DD
−
V
SS
−
0.3 to V
SS
+ 6.5
V
Input voltage
V
IN
SCL, SDA
V
SS
−
0.3 to V
SS
+ 6.5
V
Output voltage
V
OUT
V
V
SS
−
0.3 to V
SS
+ 6.5
SDA, 32KO,
INT2
*1
Operating ambient temperature
−
−40
to +85
°C
T
opr
Storage temperature
T
stg
−
−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
(V
SS
= 0 V)
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
*1
Power supply voltage
Ta =
−40
to +85°C
1.3
3.0
5.5
V
V
DD
*2
Time keeping power supply voltage
Ta =
−40
to +85°C
V
DET
−
0.15
−
5.5
V
V
DDT
Crystal oscillator C
L
value
C
L
−
−
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 V
DET
(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
V
STA
Within 10 seconds
1.1
−
5.5
V
Oscillation start time
t
STA
−
−
−
1
s
*1
IC-to-IC frequency deviation
δIC
−
−10
−
+10
ppm
Frequency voltage deviation
δV
V
DD
= 1.3 to 5.5 V
−3
−
+3
ppm/V
External capacitance
C
g
Applied to XIN pin
−
−
9.1
pF
Internal oscillation capacitance
C
d
Applied to XOUT pin
−
8
−
pF
*1.
Reference value
Seiko Instruments Inc.
5
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