S-35390A

Manufacturer Part NumberS-35390A
Description2-Wire Real Time Clock
ManufacturerSeiko Instruments
S-35390A datasheet
 


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Rev.1.2
_00
2-WIRE REAL-TIME CLOCK
Features
• Low current consumption:
• Wide operating voltage range:
• Minimum time keeping operation voltage: 1.1 V
• Built-in clock adjustment function
• Built-in free user register
2
*1
• 2-wire (I
C-BUS)
CPU interface
• Built-in alarm interrupter
• Built-in flag generator at power down or power on
• Auto calendar up to the year 2099, automatic leap year calculation function
• Built-in constant voltage circuit
• Built-in 32 kHz crystal oscillator circuit (C
• Package: 8-pin SOP (JEDEC), 8-pin TSSOP, SNT-8A
2
*1. I
C-BUS is a trademark of Philips Electronics N.V.
Applications
• Digital still cameras
• Digital video cameras
• Electronic power meters
• DVD recorders
• TVs, VCRs
• PHS
• Mobile phones
• Car navigation
The S-35390A is a low-current-consumption 2-wire CMOS real-time clock IC
that features a wide operating voltage range (1.3 V to 5.5 V) and can be
driven on a variety of supply voltages, from a main supply to a backup
supply. The time keeping current consumption of 0.25 µA and minimum
time keeping operation voltage of 1.1 V enable greatly increased battery
duration.
In a system that operates on a backup battery, the free register incorporated
in the real-time clock can be used for the user backup memory function.
The user register can hold data on a supply voltage as low as 1.2 V (min.),
so the data stored in the register before the main power supply was cut can
be called any time after the voltage is restored.
This product also includes a clock adjustment function that enables wide-
ranging correction of deviation in the frequency of the crystal oscillator at a
minimum resolution of 1 ppm. Also, by combining this function with a
temperature sensor, the clock adjustment value can be set in accordance
with changes in the temperature, which makes it possible to realize a clock
function that retains a high degree of accuracy regardless of temperature
variation.
0.25 µA typ. (V
DD
1.3 to 5.5 V
built in, C
external)
d
g
Seiko Instruments Inc.
S-35390A
= 3.0 V, Ta = 25°C)
1

S-35390A Summary of contents

  • Page 1

    ... PHS • Mobile phones • Car navigation The S-35390A is a low-current-consumption 2-wire CMOS real-time clock IC that features a wide operating voltage range (1 5.5 V) and can be driven on a variety of supply voltages, from a main supply to a backup supply. The time keeping current consumption of 0.25 µA and minimum time keeping operation voltage of 1 ...

  • Page 2

    ... INT1 2 7 XOUT 3 6 XIN 4 5 VSS S-35390A-T8T1 Figure 2 SNT-8A Top view INT1 1 8 VDD XOUT 2 7 SDA XIN 3 6 SCL 4 5 INT2 VSS S-35390A-I8T1G Figure 3 Seiko Instruments Inc. Tape Reel FJ008-D FT008-E PH008-A VDD SDA SCL INT2 Rev.1.2 _00 ...

  • Page 3

    ... VDD Positive power supply pin Table 1 Description external) g voltage Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A Configuration Nch open-drain output (no protective diode on the side of VDD)   Nch open-drain output (no protective diode on the side of VDD) CMOS input (no protective diode on the side of VDD) ...

  • Page 4

    ... REAL-TIME CLOCK S-35390A Block Diagram XIN Division, timing Oscillator XOUT Clock adjustment register Status register_1 Status register_2 Power supply VDD voltage detector Constant voltage circuit VSS 4 INT1 register_1 generator Comparator 1 Second Minute Comparator 2 INT1 register_2 Shift register Figure 4 Seiko Instruments Inc. ...

  • Page 5

    ... V Within 10 seconds STA = 3 STA DD δIC  δV = 1 Applied to XIN pin g C Applied to XOUT pin d Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A Rating Unit − − − −40 to +85 °C − ...

  • Page 6

    ... REAL-TIME CLOCK S-35390A DC Electrical Characteristics (Ta = −40 to +85° 3.0 V, DS-VT-200 crystal oscillator (C DD Parameter Symbol Current consumption 1 I DD1 Current consumption 2 I DD2 Input current leakage 1 I IZH Input current leakage 2 I IZL Output current leakage 1 I OZH Output current leakage 2 ...

  • Page 7

    ... S-35390A Unit Max. 400 kHz  µs  µs µs 0.9  µs  µs  ns  ns  µs 0.3 µs µs 0.3  ...

  • Page 8

    ... REAL-TIME CLOCK S-35390A Timing Chart SCL t SU.STA SDA IN SDA OUT Operation 1. Communication data configuration The master device on the system generates a start condition to the slave device to communicate. Then it transmits a 4-bit device address, 3-bit command, and 1-bit read/write command on the SDA bus. ...

  • Page 9

    ...   A2WE AM/PM A2HE H20 A2mE m40 m20 * Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A Data 12/24 SC1 SC0 RESET Y10 M10 D10   ...

  • Page 10

    ... REAL-TIME CLOCK S-35390A Register Configuration 1. Real-time data register The real-time data register is a 56-bit register that stores the BCD code of the year, month, day, day of week, hour, minute, and second data. Any read/write operation performed by the real-time data access command transmits or receives the data from the LSB which is the first digit of the year. ...

  • Page 11

    ... Be sure to write “1” to the reset flag when applying the power supply voltage to the IC SC1 INT2 INT1 R R R/W Figure 9 Status Register_1 0: 12-hour expression 1: 24-hour expression Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A SC0 12/24 RESET R/W R Read-enabled W: Write-enabled R/W: Read/write-enabled ) ...

  • Page 12

    ... REAL-TIME CLOCK S-35390A 3. Status Register_2 Status register_2 is an 8-bit register that is used to display and set various modes. The bit configuration is shown below MSB TEST INT2AE R/W R/W B7: TEST The TEST flag is a bit for testing the IC. If the TEST flag is set to “1”, the IC is switched to the TEST mode. If this flag is “ ...

  • Page 13

    ... W4 MSB AM/ A2HE H20 H10 MSB A2mE m40 m20 m10 m8 m4 MSB *       S-35390A W2 W1 LSB H2 H1 LSB m2 m1 LSB *1  LSB *1  LSB 13 ...

  • Page 14

    ... REAL-TIME CLOCK S-35390A (2) Selected frequency steady interrupt Data set in INT1 register_1 and INT1 register_2 is considered as frequency duty data. By setting each bit from the register to “1”, the frequency corresponding to each bit is selected in an ANDed form. The SC bits configure a 3-bit SRAM type register that can be set freely by users. These bits can be read and written within the operating voltage range (1 ...

  • Page 15

    ... The free register is a 1-byte SRAM type register that can be set freely by users. It can be read and written within the operating voltage range (1.3 to 5.5 V MSB R/W R R/W R/W R/W Figure 14 Clock Adjustment Register R/W R/W R/W Figure 15 Free Register Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A R/W R/W R/W R/W: Read/write-enabled R/W R/W R/W R/W: Read/write-enabled LSB LSB 15 ...

  • Page 16

    ... REAL-TIME CLOCK S-35390A Initialization at Power-on and Power-on Detector When power is applied to this IC, status register_1 is set to “80h” (bit 7 (POC flag) of status register_1 is set to “1”) by the power-on detector and clock is output from the adjust the oscillation frequency. In normal use, the IC must be initialized at power-on. Initialization is performed by writing “ ...

  • Page 17

    ... Power Supply Voltage Detector S-35390A has an internal power supply voltage detector, which monitors drops in the power supply voltage by reading the BLD flag. This circuit samples the voltage for only 15.6 ms per second. If the power supply voltage drops below the detection voltage (V of internal status register_1 is set to “ ...

  • Page 18

    ... REAL-TIME CLOCK S-35390A Processing of Nonexistent Data and End-of-Month When real-time data is written, the data is checked for validity, invalid data is processed, and the end-of- month is corrected. 1. Processing of nonexistent data Register Year data Month data Day data Day of week data *1 Hour data ...

  • Page 19

    ... Comparator Alarm interrupt Minute Hour Week Day Real time data When set “H” Hour “m” minute H h 00m Change by the program Change by the program OFF Alarm time match period S-35390A Month Year ...

  • Page 20

    ... REAL-TIME CLOCK S-35390A (H − Real time data Change by the program INT1AE / INT2AE INT1 pin / INT2 pin Alarm time match *1. Once it clears, even if it enables again within a coincidence period, “L” will not be output from an INT pin (or 1 INT 2 *2. When an alarm output is turned on by change by the program within a coincidence period, “ ...

  • Page 21

    ... Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK Change by program Minute-carry processing “L” signal is output again if 123 µs or less. Minute-carry Minute-carry processing processing “H” signal is output if approx. 123 µs or more. “L” signal is output by next minute-carry processing. S-35390A ...

  • Page 22

    ... REAL-TIME CLOCK S-35390A (5) Per-minute steady interrupt output 2 ( When the first minute carry is performed after the INT1 pin output mode is set as per-minute steady interrupt 2 using status register_2, low is output from the INT1 pin for a period of 7 synchronization with the minute carry processing inside the IC. However, when real-time data is read, the minute carry processing is delayed by a maximum of 0 ...

  • Page 23

    ... Hz clock is output from the INT1 pin. INT2AE = INT2ME = INT2FE = 32kE = INT1AE = INT1ME = 0 INT1FE INT1 pin Figure 22 0.5 s 0.5 s INT Pin Output Timing During Power-on Detector Operation 1 Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A Change by reset command OFF 23 ...

  • Page 24

    ... REAL-TIME CLOCK S-35390A Clock Adjustment Function A clock adjustment function is provided to logically perform slow/fast adjustment of the 32 kHz clock and correct a slow/fast clock with high accuracy. Use the clock adjustment register to set this function. When not using this function, be sure to set it to 00h. ...

  • Page 25

    ... B7 = “1” (minimum resolution = 1.017 ppm) indicates the correction is impossible. − (Target oscillation frequency) × (Current oscillation frequency) (1.000000) − (0.999920) − 6 (0.999920) × (3.052 × (1.000000) − (0.999920) − 6 (0.999920) × (1.017 × Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A (Current oscillation frequency actual measurement value (Minimum resolution ...

  • Page 26

    ... REAL-TIME CLOCK S-35390A Serial Interface The S-35390A receives various commands via an I covers the transfer methods via I 1. Start condition The start condition is established at the point where the SDA line changes from “H” to “L” when the SCL line is “H” level. All operations start with the start condition. ...

  • Page 27

    ... Data is transferred 8 bits in a row. Subsequently, in the 9th clock cycle period, the device on the system bus that is receiving the data changes the SDA line to “L” and returns the acknowledge signal to acknowledge data reception. SCL (S-35390A input) SDA (Master output) SDA ...

  • Page 28

    ... Real-time data access 2 1 SCL SDA MSB Command I/O mode switching *1. During reading, set NO_ACK to 1. During reading, transmit ACK = 0 to S-35390A from the master device LSB LSB MSB Year data I/O mode switching Figure 26 Real-time Data Access 1 ...

  • Page 29

    ... SDA MSB Command I/O mode switching *1. 0: INT1 register_1 selected, 1:INT1 register_2 selected *2. During reading, set NO_ACK to 1. *3. During reading, transmit ACK = 0 to S-35390A from the master device. Figure 29 INT1 Register_1 Access and INT1 Register_2 Access R ...

  • Page 30

    ... REAL-TIME CLOCK S-35390A SCL SDA *1. 0: INT1 register_1 selected, 1:INT1 register_2 selected *2. During reading, set NO_ACK to 1. Figure 30 INT1 Register_1 and INT1 Register_2 (Frequency Duty Data) Access (5) Clock adjustment register access SCL SDA *1. During reading, set NO_ACK to 1. (6) Free register access ...

  • Page 31

    ... TEST = 1 NO END *1. If conditions are poor (e.g noisy environment) and there is a high probability that commands transmitted via serial communication will be garbled recommended to verify the TEST flag. YES Figure 33 Initialization Flow Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK S-35390A 31 ...

  • Page 32

    ... Caution 1. Because the I/O pin has no protective diode on the VDD side, the relation possible. But pay careful attention to the specifications Communication should be executed after the system power supply is turned on and a stable state is obtained. S-35390A VDD VSS XIN C g Caution Communication should be executed after the system power supply is turned on and a stable state is obtained ...

  • Page 33

    ... Since crystal oscillation is sensitive to external noise (the clock accuracy is affected), the following measures are essential for optimizing the oscillator configuration. (1) Place the S-35390A, crystal oscillator, and external capacitor (C possible. (2) Increase the insulation resistance between pins and the substrate wiring patterns of XIN and XOUT ...

  • Page 34

    ... S-35390A 2. Measurement of oscillation frequency When the S-35390A is turned on, the internal power-on detector operates and a signal output from the INT1 pin to select the crystal oscillator and optimize the C measure the signal with a frequency counter following the circuit configuration shown in Figure ...

  • Page 35

    ... Figure 39 Crystal Oscillator Setting Flow Seiko Instruments Inc. 2-WIRE REAL-TIME CLOCK value in accordance g Set to center of variable capacitance Does frequency match? YES g Make fine adjustment of frequency using variable capacitance value (equivalent series resistance S-35390A * ...

  • Page 36

    ... REAL-TIME CLOCK S-35390A Product Name Structure 1. 8-Pin SOP(JEDEC), 8-Pin TSSOP package S-35390A - xxxx 2. SNT-8A package S-35390A - 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 ...

  • Page 37

    ... V [V] DD 1.0 0.9 0.8 0.7 0.6 I DD1 0.5 [µA] V 0.4 DD 0.3 0.2 0.1 0 −40 − [°C] characteristics 25°C, C 100 ∆f/f 0 [ppm −20 −40 −60 −80 −100 [pF] g S-35390A = 5 3 6pF ...

  • Page 38

    ... REAL-TIME CLOCK S-35390A (7) Oscillation frequency vs 25° ∆f/f 0 [ppm] −10 −20 −30 −40 − (9) Oscillation start time vs. C 500 450 400 350 300 t STA 250 V [ms] DD 200 150 100 (11) Output current characteristics 2 (V SDA pin 25° ...

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    ... 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 ...