S-35392A

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. (VDD = 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 (I2C-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 (Cd built in, Cg 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 − − Configuration Nch open-drain output (no protective diode at VDD) − SCL SDA VDD − Nch open-drain output 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 I2C-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 I2C-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 3 2KO, 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 Day of Second Minute Hour Day Month Year the week Comparator 2 Free register Low power supply voltage detector Power-on detector Constantvoltage 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 VDD − VSS − 0.3 to VSS + 6.5 V Input voltage VIN SCL, SDA VSS − 0.3 to VSS + 6.5 V Output voltage VOUT V VSS − 0.3 to VSS + 6.5 SDA, 32KO, INT2 *1 Operating ambient temperature − −40 to +85 °C Topr 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 Ta = −40 to +85°C 1.3 3.0 5.5 V VDD *2 Time keeping power supply voltage Ta = −40 to +85°C VDET − 0.15 − 5.5 V VDDT 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, VDD = 3.0 V, VSS = 0 V, VT-200 crystal oscillator (CL = 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 Seiko Instruments Inc. 5 2-WIRE REAL-TIME CLOCK S-35392A DC Electrical Characteristics Rev.1.3_00 Table 5 DC Characteristics (VDD = 3.0 V) (Ta = −40 to +85°C, VSS = 0 V, VT=200 crystal oscillator (CL = 6 pF, 32.768 kHz, Cg = 9.1 pF) manufactured by Seiko Instruments Inc.) Parameter Symbol Applicable Pin Conditions Min. Typ. Max. Unit Current consumption 1 IDD1 − Out of communication − 0.45 1.13 µA During communication − 6 14 µA Current consumption 2 IDD2 − (SCL = 100 kHz) Input current leakage 1 IIZH SCL, SDA VIN = VDD −0.5 − 0.5 µA Input current leakage 2 IIZL SCL, SDA VIN = VSS −0.5 − 0.5 µA Output current leakage 1 IOZH −0.5 − 0.5 µA SDA, 32KO, INT2 VOUT = VDD Output current leakage 2 Input voltage 1 Input voltage 2 Output current 1 Output current 2 Power supply voltage detection voltage IOZL VIH VIL IOL1 IOL2 VDET SDA, 32KO, INT2 VOUT = VSS SCL, SDA − SCL, SDA − VOUT = 0.4 V 32KO, INT2 SDA VOUT = 0.4 V − − −0.5 0.8 × VDD VSS − 0.3 3 5 0.65 − − − 5 10 1 0.5 VSS + 5.5 0.2 × VDD − − 1.35 µA V V mA mA V Table 6 DC Characteristics (VDD = 5.0 V) (Ta = −40 to +85°C, VSS = 0 V, VT-200 crystal oscillator (CL = 6 pF, 32.768 kHz, Cg = 9.1 pF) manufactured by Seiko Instruments Inc.) Parameter Symbol Applicable Pin Conditions Min. Typ. Max. Unit Current consumption 1 IDD1 − Out of communication − 0.6 1.4 µA During communication − 14 30 µA Current consumption 2 IDD2 − (SCL = 100 kHz) Input current leakage 1 IIZH SCL, SDA VIN = VDD −0.5 − 0.5 µA Input current leakage 2 IIZL SCL, SDA VIN = VSS −0.5 − 0.5 µA Output current leakage 1 IOZH −0.5 − 0.5 µA SDA, 32KO, INT2 VOUT = VDD Output current leakage 2 Input voltage 1 Input voltage 2 Output current 1 Output current 2 Power supply voltage detection voltage IOZL VIH VIL IOL1 IOL2 VDET SDA, 32KO, INT2 VOUT = VSS SCL, SDA − SCL, SDA − VOUT = 0.4 V 32KO, INT2 SDA VOUT = 0.4 V − − −0.5 0.8 × VDD VSS − 0.3 5 6 0.65 − − − 8 13 1 0.5 VSS + 5.5 0.2 × VDD − − 1.35 µA V V mA mA V 6 Seiko Instruments Inc. Rev.1.3_00 AC Electrical Characteristics Table 7 Measurement Conditions VIH = 0.9 × VDD, VIL = 0.1 × VDD 20 ns VOH = 0.5 × VDD, VOL = 0.5 × VDD 100 pF + pull-up resistor 1 kΩ 2-WIRE REAL-TIME CLOCK S-35392A VDD Input pulse voltage Input pulse rise/fall time Output determination voltage Output load R = 1 kΩ SDA C = 100 pF Remark The power supplies of the IC and load have the same electrical potential. Output Load Circuit Figure 6 Table 8 Parameter SCL clock frequency SCL clock low time SCL clock high time SDA output delay time*1 Start condition setup time Start condition hold time Data input setup time Data input hold time Stop condition setup time SCL, SDA rise time SCL, SDA fall time Bus release time Noise suppression time AC Electrical Characteristics Symbol fSCL tLOW tHIGH tPD tSU.STA tHD.STA tSU.DAT tHD.DAT tSU.STO tR tF tBUF tI VDD *2 ≥ 1.3 V Min. Typ. Max. 0 4.7 4 − − − − − − − − − − − − − 100 (Ta = −40 to +85°C) VDD *2 ≥ 3.0 V Unit Min. Typ. Max. 0 1.3 0.6 − − − − − − − − − − − − − 400 kHz − 4.7 4 250 0 4.7 − − 3.5 − − − − − 0.6 0.6 100 0 0.6 − − 0.9 − − − − µs µs µs µs µs ns − − 4.7 − 1 0.3 − − 100 − − 1.3 − 0.3 0.3 − − 50 µs µs µs µs µs ns *1. Since the output format of the SDA pin is Nch open-drain output, SDA output delay time is determined by the values of the load resistance (RL) and load capacity (CL) outside the IC. Therefore, use this value only as a reference value. *2. Regarding the power supply voltage, refer to “ Recommended Operation Conditions”. tF tHIGH tLOW tR SCL tHD.DAT tSU.DAT tSU.STO tSU.STA tHD.STA SDA (Input from S-35392A) tPD tBUF SDA (Output from S-35392A) Figure 7 Bus Timing Seiko Instruments Inc. 7 2-WIRE REAL-TIME CLOCK S-35392A Configuration of Data Communication 1. Configuration of data communication Rev.1.3_00 For data communication, the master device in the system generates a start condition for the S-35392A. Next, the master device transmits 4-bit device code “0110”, 3-bit command and 1-bit Read/Write command to the SDA bus. After that, output or input is performed from B7 of data. If data I/O has been completed, finish communication by inputting a stop condition to the S-35392A. The master device generates an acknowledgment signal for every 1-byte. Regarding details, refer to “ Serial Interface”. Start condition Device code STA 0 1 1 0 C2 Command C1 C0 Read/Write bit Acknowledgment bit R/W ACK Stop condition 1-byte data B7 B6 B5 B4 B3 B2 B1 B0 ACK STP Figure 8 Data Communication 8 Seiko Instruments Inc. Rev.1.3_00 2. Configuration of command 2-WIRE REAL-TIME CLOCK S-35392A 8 types of command are available for the S-35392A, The S-35392A does Read/Write the various registers by inputting these fixed codes and commands. The S-35392A does not perform any operation with any codes and commands other than those below. Table 9 Device Code C2 C1 C0 0 0 0 0 0 1 Command Description Status register 1 access Status register 2 access B7 RESET Y1 M1 0 1 0 Real-time data 1 access (year data to) D1 W1 H1 m1 s1 *1 List of Command Data B6 12 / 24 B5 SC0 Y4 M4 D4 W4 H4 m4 s4 *2 B4 SC1 Y8 M8 D8 − *6 *2 B3 INT1 *3 B2 INT2 *3 B1 BLD *4 B0 POC*4 *2 *5 INT1FE INT1ME INT1AE SC2 INT2FE INT2ME INT2AE TEST Y2 M2 D2 W2 H2 m2 s2 Y10 M10 D10 − *6 Y20 −*6 D20 − *6 Y40 −*6 −*6 − *6 Y80 −*6 −*6 −*6 −*6 −*6 −*6 H8 m8 s8 H10 m10 s10 H20 m20 s20 AM / PM m40 s40 AM / PM 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 −*6 −*6 −*6 A1WE A1mE m40 s40 −*6 m40 INT1 register access 0110 1 0 0 (alarm time 1: week/hour/minute) (INT1AE = 1, INT1ME = 0, INT1FE = 0) INT1 register access (free register) (settings other than alarm time 1) INT2 register access (alarm time 2: week/hour/minute) (INT2AE = 1, INT2ME = 0, 1 0 1 INT2FE = 0) INT2 register access (output of user-set frequency) (INT2ME = 0, INT2FE = 1) 1 1 0 Clock correction register access W1 H1 m1 W2 H2 m2 W4 H4 m4 −*6 H8 m8 −*6 H10 m10 −*6 H20 m20 AM / PM A1HE SC3*2 SC4*2 SC5*2 SC6*2 SC7*2 SC8*2 SC9*2 SC10*2 W1 H1 m1 W2 H2 m2 W4 H4 m4 −*6 H8 m8 −*6 H10 m10 −*6 H20 m20 −*6 m40 A2WE A2mE AM / PM A2HE 1 Hz V0 2 Hz V1 4 Hz V2 8 Hz V3 16 Hz V4 SC11*2 SC12*2 SC13*2 V5 V6 V7 1 1 1 Free register access F0 F1 F2 F3 F4 F5 F6 F7 *1. Write-only flag. The S-35392A 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. Seiko Instruments Inc. 9 2-WIRE REAL-TIME CLOCK S-35392A Configuration of Register 1. Real-time data register Rev.1.3_00 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) Start bit of real-time data 1 data access Y1 B7 Month data (01 to 12) M1 B7 Day data (01 to 31) D1 B7 Day of the week data (00 to 06) W1 B7 Hour data (00 to 23 or 00 to 11) Start bit of real-time data 2 data access H1 B7 H2 H4 H8 H10 H20 0 B0 W2 W4 0 0 0 0 0 B0 D2 D4 D8 D10 D20 0 0 B0 M2 M4 M8 M10 0 0 0 B0 Y2 Y4 Y8 Y10 Y20 Y40 Y80 B0 AM / PM Minute data (00 to 59) m1 B7 m2 m4 m8 m10 m20 m40 0 B0 Second data (00 to 59) s1 B7 s2 s4 s8 s10 s20 s40 0 B0 Figure 9 Real-Time Data Register 10 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 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 AM / PM 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) Seiko Instruments Inc. 11 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 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 W B6 B5 SC0 R/W B4 SC1 R/W B3 INT1 R R: W: R/W: B2 INT2 R B1 BLD R B0 POC R 12 / 24 R/W Read Write Read/Write Figure 10 B0 : POC Status Register 1 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 function has come. The INT1 flag in “1” in the alarm 1 function mode, the INT2 flag in “1” in the 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 : 12 / 24 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”. 12 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 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 R/W B6 INT1ME R/W B5 INT1AE R/W B4 SC2 R/W B3 INT2FE R/W B2 INT2ME R/W B1 INT2AE R/W B0 TEST R/W R/W: Read/Write Figure 11 B0 : TEST Status Register 2 This is a test flag for SII. Be sure to set this flag to “0” in use. If this flag is set to “1”, be sure to initialize to set “0”. B1 : INT2AE, B2 : INT2ME, B3 : INT2FE These bits are used to select the output mode for the INT2 pin. Table 10 shows how to select the mode. To use alarm 2 interrupt, access the INT2 register after setting the alarm interrupt mode. Table 10 INT2AE INT2ME INT2FE Output Modes for INT2 Pin INT2 Pin Output Mode *1. 0 0 0 −*1 0 1 −*1 1 0 −*1 1 1 1 0 0 Don’t care (Both of 0 and 1 are acceptable). No interrupt Output of user-set frequency Per-minute edge interrupt Minute-periodical interrupt 1 (50% duty) Alarm 2 interrupt B4 : SC2 This is an SRAM type register that can be freely set by users. B5 : INT1AE, B6 : INT1ME, B7 : INT1FE To use the alarm 1 function, access the INT register 1 after setting INT1AE = “1”, INT1ME = “0”, and INT1FE = “0”. In other settings than this, these flags are disable for setting the alarm time (free registers). Seiko Instruments Inc. 13 2-WIRE REAL-TIME CLOCK S-35392A 4. INT1 register and INT2 register Rev.1.3_00 The INT1 register is to set up the alarm time. The INT2 register is to set up the output of user-set frequency or alarm interrupt. To switch the output mode, use the status register 2. The INT1 register works as an alarm-time data register in the alarm 1 interrupt mode selected by users. The INT1 flag (B3 in the status register) displays the alarm time when it matches. The INT2 register works as an alarm-time data register in the alarm interrupt mode selected by using the status register 2. In the mode output of user-set frequency, the INT2 register works as a data register to set up the frequency for output clock. Clock pulse and output of alarm interrupt are output from the INT2 pin. And The INT2 flag (B2 in the status register) displays the alarm time when it matches. (1) Alarm interrupt Users can set the alarm time (the data of day of the week, hour, minute) by using the INT1 and INT2 registers which are 3-byte data registers. The configuration of register is as well as the data register of day of the week, hour, minute, in the real-time data register; is expressed 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. INT1 register W1 B7 W2 W4 0 0 0 0 A1WE B0 M/ H10 H20 APM A1HE B0 INT2 register W1 B7 W2 W4 0 0 0 0 A2WE B0 M/ H10 H20 APM A2HE B0 H1 B7 H2 H4 H8 H1 B7 H2 H4 H8 m1 B7 m2 m4 m8 m10 m20 m40 A1mE B0 m1 B7 m2 m4 m8 m10 m20 m40 A2mE B0 Figure 12 INT1 Register and INT2 Register (Alarm-Time Data) The INT1 register has A1WE, A1HE, A1mE at B0 in each byte. It is possible to make data 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 INT2 register. Setting example: alarm time “7:00 pm” in the INT1 register (a) 12-hour expression (status register 1 B6 = 0) set up 7:00 PM Data written to INT1 register −*1 −*1 −*1 −*1 −*1 Day of the week Hour 1 1 1 0 0 Minute 0 0 0 0 0 B7 *1. Don’t care (Both of 0 and 1 are acceptable). (b) 24-hour expression (status register 1 B6 = 1) −*1 0 0 −*1 1 0 0 1 1 B0 set up 19:00 PM Data written to INT1 register −*1 −*1 −*1 −*1 −*1 −*1 Day of the week Hour 1 0 0 1 1 0 Minute 0 0 0 0 0 0 B7 *1. Don’t care (Both of 0 and 1 are acceptable). *2. Set up the AM / PM flag along with the time setting. −*1 1*2 0 0 1 1 B0 14 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A (2) Free register (INT1 register) The INT1 register is a 1-byte SRAM type register that can be set freely by users. B7 SC3 R/W B6 SC4 R/W B5 SC5 R/W B4 SC6 R/W B3 SC7 R/W B2 SC8 R/W B1 SC9 R/W B0 SC10 R/W R/W: Read/Write Figure 13 INT1 Register (Free Register) (3) Output of user-set frequency (INT2 register) The INT2 register 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. SC11 to SC13 in the INT2 register are 3-bit SRAM type registers that can be freely set by users. B7 1 Hz R/W B6 2 Hz R/W B5 4 Hz R/W B4 8 Hz R/W B3 16 Hz R/W B2 SC11 R/W B1 SC12 R/W B0 SC13 R/W R/W: Read/Write Figure 14 Example: B7 to B3 = 50h INT2 Register (Data Register for Output Frequency) 16 Hz 8 Hz 4 Hz 2 Hz 1 Hz INT2 pin output Status register 2 • Set to INT2FE = 1 Figure 15 Example of Output from INT2 Register (Data Register for Output Frequency) Seiko Instruments Inc. 15 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 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 V0 R/W B6 V1 R/W B5 V2 R/W B4 V3 R/W B3 V4 R/W B2 V5 R/W B1 V6 R/W B0 V7 R/W R/W: Read/Write Figure 16 Clock-Correction Register 6. Free register The free register is a 1-byte SRAM type register that can be set freely by users. B7 F0 R/W B6 F1 R/W B5 F2 R/W B4 F3 R/W B3 F4 R/W B2 F5 R/W B1 F6 R/W B0 F7 R/W R/W: Read/Write Figure 17 Free Register 16 Seiko Instruments Inc. Rev.1.3_00 Power-on Detector and Register Status 2-WIRE REAL-TIME CLOCK S-35392A The power-on detection circuit operates by power-on the S-35392A, as a result each register is cleared; each register is set as follows. Real-time data register : Status register 1 : Status register 2 : INT1 register : INT2 register : Clock correction register : Free register : 00 (Y), 01 (M), 01 (D), 0 (day of the week), 00 (H), 00 (M), 00 (S) “01h” “01h” “80h” “00h” “00h” “00h” “1” is set in the POC flag (B0 in the status register 1) to indicate that power has been applied. In this case, be sure to initialize. The POC flag is set to “0” due to initialization. (Refer to “ Register Status After Initialization”.) For the regular operation of power-on detection circuit, as seen in Figure 18, the period to power-up the S-35392A is that the voltage reaches 1.3 V within 10 ms after setting the IC’s power supply voltage at 0 V. When the POC flag (B0 in the status register) is not in “1”, in this case, power-on the S-35392A once again. 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 0V *1 *1. 0 V indicates that there are no potential differences between the VDD pin and VSS pin of the S-35392A. Figure 18 How to Raise the Power Supply Voltage Seiko Instruments Inc. 17 2-WIRE REAL-TIME CLOCK S-35392A Register Status After Initialization The status of each register after initialization is as follows. Real-time data register : Status register 1 : Rev.1.3_00 Status register 2 : INT1 register : INT2 register : Clock correction register : Free register : 00 (Y), 01 (M), 01 (D), 0 (day of the week), 00 (H), 00 (M), 00 (S) “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 19.) “00h” “00h” “00h” “00h” “00h” Write to status register 1 1 9 18 1 Read from status register 1 9 18 SCL R/W ACK START START STOP ACK R/W NO_ACK ACK STOP 0 0 110000 1 L LH LL L L L 0 SDA 0 11 0 0000 10100000 Device code + command B7 B5 Device code + command B7 B5 : Not reset Write “1” to reset flag and SC0. : Output from S-35392A : Input from master device Figure 19 Status Register 1 Data at Initialization 18 Seiko Instruments Inc. Rev.1.3_00 Low Power Supply Voltage Detection Circuit 2-WIRE REAL-TIME CLOCK S-35392A The S-35392A 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, be sure to initialize the circuit. Without initializing, Read in the next BLD flag is done after sampling, the BLD flag gets reset to “0”. In this case, be sure to initialize although the BLD flag is in “0” because the internal circuit may be in the indefinite status. VDD Detection voltage Hysteresis width 0.15 V approximately Release voltage BLD flag reading Sampling pulse 15.6 ms 1s 1s Stop Stop Stop BLD flag Figure 20 Timing of Low Power Supply Voltage Detection Circuit Circuits Power-on and Low Power Supply Voltage Detection Figure 21 shows the changes of the POC flag and BLD flag due to VDD fluctuation. VDD Low power supply voltage detection voltage Low power supply voltage detection voltage VSS POC flag BLD flag Status register 1 reading Figure 21 POC Flag and BLD Flag Seiko Instruments Inc. 19 2-WIRE REAL-TIME CLOCK S-35392A Correction of Nonexistent Data and End-of-Month Rev.1.3_00 When users write the real-time data, the S-35392A checks it. In case that the data is invalid, the S-35392A does the following procedures. 1. Processing of nonexistent data Table 11 Register Year data Month data Day data Day of the week data 24-hour Hour data *1 12-hour Minute data Second data *2 Normal Data 00 to 99 01 to 12 01 to 31 0 to 6 0 to 23 0 to 11 00 to 59 00 to 59 Processing of Nonexistent Data Nonexistent Data XA to XF, AX to FX 00, 13 to 19, XA to XF 00, 32 to 39, XA to XF 7 24 to 29, 3X, XA to XF 12 to 19, 2X, 3X, XA to XF 60 to 79, XA to XF 60 to 79, XA to XF Result 00 01 01 0 00 00 00 00 *1. In a 12-hour expression, Write the AM / PM flag (B1 in hour data in the real-time data register). In 24-hour expression, the AM / PM 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. 20 Seiko Instruments Inc. Rev.1.3_00 Alarm 1 Function and INT2 Pin Output Mode 2-WIRE REAL-TIME CLOCK S-35392A In the output mode for INT2 pin, users are able to select the output; alarm 2 interrupt, user-set frequency, per-minute edge interrupt, minute-periodical interrupt. To switch the output mode for INT2 pin and the alarm 1 function, use the status register 2. Refer to 3. Status register 2 in “ Configuration of Register”. When switching the output mode for INT2 pin, be careful of the output status of the pin. Especially, when using alarm 2 interrupt output, or the output of user-set frequency, switch the output mode after setting “00h” in the INT2 register. In per-minute edge interrupt output/minute-periodical interrupt output, it is unnecessary to set data in the INT2 register for users. Refer to the followings regarding each operation of output modes. 1. Alarm 1 function and alarm 2 interrupt Alarm 2 interrupt output is the function to set the INT2 flag “H” by the output “L” from the INT2 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 INT2AE in the status register 2. By Read, the INT2 flag is once cleared automatically. In the alarm 1 function, the INT1 flag (B3 in the status register1) is set to “H” when the set time has come. The INT1 flag is also cleared once by Read. In the alarm 1 function, set the data of day of the week, hour, minute of the alarm time in the INT1 register. In alarm 2 interrupt, set in the INT2 register. Refer to “4. INT1 register and INT2 register” in “ Configuration of Register”. Alarm setting of “W (day of the week), H (hour), m (minute)” Status register 2 setting • Alarm 1 function INT1ME = INT1FE = 0 • Alarm 2 interrupt INT2ME = INT2FE = 0 INTx register alarm enable flag • AxHE = AxmE = AxWE = "1" INT1 register INT2 register mx Hx Wx Alarm 1 output (B3 in status register 1) Alarm 2 interrupt (INT2 pin)/ alarm 2 output (B2 in status register 1) Comparator Second Minute Hour Real-time data W (day of the week) Real-time data H h (m − 1) m 59 s Change by program INT1AE/INT2AE Alarm time matches INT1 flag/ INT2 flag Alarm time matches INT2 pin Day of the week Day Month Year H h 00 m 00 s 01 s 59 s H h (m + 1) m 00 s Change by program Change by program Status register 1 reading *1 OFF Period when alarm time matches *1. If users clear INT2AE once; “L” is not output from the INT2 pin by setting INT2AE enable again, within a period when the alarm time matches real-time data. Figure 22 Alarm Interrupt Output Timing (1/2) Seiko Instruments Inc. 21 2-WIRE REAL-TIME CLOCK S-35392A Alarm setting of “H (hour)” Status register 2 setting • Alarm 1 function INT1ME = INT1FE = 0 • Alarm 2 interrupt INT2ME = INT2FE = 0 INTx register alarm enable flag • AxmE = AxWE = "0", AxHE = "1" Rev.1.3_00 INT1 register INT2 register mx Hx Wx Dx Mx Yx Alarm 1 output (B3 in status register 1) Comparator Alarm 2 interrupt (INT2 pin)/ alarm 2 output (B2 in status register 1) Second Minute Hour Real-time data Day of Day Month Year the week Real-time data (H − 1) h 59 m 59 s Change by program H h 00 m 00 s 01 s 59 s H h 01 m 00 s H h 59 m 59 s (H + 1) h 00 m 00 s Change by program Change by program Change by program INT1AE/INT2AE Alarm time matches Status register 1 reading Status register 1 reading INT1 flag/ INT2 flag Alarm time matches INT2 pin OFF *1 Alarm time matches*2 *1 OFF Period when alarm time matches *1. If users clear INT2AE once; “L” is not output from the INT 2 pin by setting 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 2 pin when the minute is counted up. Figure 23 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 2 pin, in the AND-form. Set up the data of frequency in the INT2 register. Refer to “4. INT1 register and INT2 register” in “ Configuration of Register” Status register 2 setting • INT2 pin output mode INT2AE = Don’t care (0 or 1), INT2ME = 0 INT2FE Free-run output starts OFF Change by program INT2 pin Figure 24 Output Timing of User-set Frequency 22 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 3. Per-minute edge interrupt output Per-minute edge interrupt output is the function to output “L” from the INT2 pin, when the first minute-carry processing is done, after selecting the output mode. To set the pin output to “H”, in the INT2 pin output mode, input “0” in INT2ME in the status register 2 in order to turn off this mode. Status register 2 setting • INT2 pin output mode INT2AE = Don’t care (0 or 1), INT2FE = 0 Change by program INT2ME Minute-carry processing OFF Minute-carry processing INT2 pin "L" is output again if this period is within 7.9 ms*1. *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 25 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 INT2 pin, when the first minute-carry processing is done, after selecting the output mode. Status register 2 setting • INT2 pin output mode INT2AE = 0 INT2ME, INT2FE Minute-carry processing INT2 pin 30 s 30 s 30 s 30 s *1 Change by program (OFF) Minute-carry processing Minute-carry processing Minute-carry processing Minute-carry processing 30 s 30 s 30 s 30 s 30 s "L" is output again if this period is within 7.9 ms . "H" is output again if this period is within 7.9 ms "L" is output at the next minute-carry processing *1. Setting the output mode disable makes the pin output “H”, while the output from the INT2 pin is in “L”. Note that pin output is set to “L” by setting enable the output mode again. Figure 26 Timing of Minute-periodical Interrupt Output 1 Seiko Instruments Inc. 23 2-WIRE REAL-TIME CLOCK S-35392A Function to Clock-Correction Rev.1.3_00 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-35392A 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-35392A 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 Correction Minimum resolution Correction range Every 20 seconds 3.052 ppm −195.3 to +192.2 ppm B0 = 1 Every 60 seconds 1.017 ppm −65.1 to +64.1 ppm 24 Seiko Instruments Inc. Rev.1.3_00 1. How to calculate (1) 2-WIRE REAL-TIME CLOCK S-35392A If current oscillation frequency > target frequency (in case the clock is fast) (Current oscillation frequency *3 *2 actual measurement value ) − (Target oscillation frequency ) (Current oscillation frequency *2 actual measurement value ) × (Minimum resolution ) *4 Correction value = 128 − Integral value *1 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 INT2 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) (1.000070) − (1.000000)  Correction value = 128 − Integral value   (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) (Target oscillation frequency) − Correction value = Integral value (Current oscillation frequency actual measurement value) (Minimum resolution) (Current oscillation frequency × actual measurement value) +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) (1.000000) − (0.999920)  +1 Correction value = Integral value   (0.999920) × (3.052 × 10-6)  = 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) (1.000000) − (0.999920)  Correction value = Integral value  +1 0.999920) × (1.017 × 10-6)  ( = 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. Seiko Instruments Inc. 25 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 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 1 0 1 B6 1 1 0 B5 1 1 1 B4 1 1 1 B3 1 1 1 • • • 0 0 0 1 1 1 • • • 0 0 0 B2 1 1 1 B1 0 0 0 B0 0 0 0 Correction Value [ppm] 192.3 189.2 186.2 • • • 6.1 3.1 0 −3.1 −6.1 −9.2 • • • −189.2 −192.3 −195.3 Rate [s/day] 16.61 16.35 16.09 • • • 0.53 0.26 0 −0.26 −0.53 −0.79 • • • −16.35 −16.61 −16.88 0 1 0 1 0 1 1 0 0 1 1 0 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 Table 14 Setting Value for Register and Correction Value (Minimum Resolution: 1.017 ppm (B0 = 1)) B7 1 0 1 B6 1 1 0 B5 1 1 1 B4 1 1 1 B3 1 1 1 • • • 0 0 0 1 1 1 • • • 0 0 0 B2 1 1 1 B1 0 0 0 B0 1 1 1 Correction Value [ppm] 64.1 63.1 62.0 • • • 2.0 1.0 0 −1.0 −2.0 −3.0 • • • −63.1 −64.1 −65.1 Rate [s/day] 5.54 5.45 5.36 • • • 0.18 0.09 0 −0.09 −0.18 −0.26 • • • −5.45 −5.54 −5.62 0 1 0 1 0 1 1 0 0 1 1 0 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 0 0 0 1 1 1 1 1 1 1 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 26 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 3. How to confirm setting value for register and result of correction The S-35392A 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 INT2 pin changes once in 20 times or 60 times, as shown in Figure 27. INT2 pin (1 Hz output) a a 19 times or 59 times a b Once a B0 = 0, a : 19 times, b : Once B0 = 1, a : 59 times, b : Once Figure 27 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] Before correction 00 h (Tave = a) 1.000080 After correction 66 h (Tave = (a × 19 + b) ÷ 20) 1.00000065 Calculating the average frequency allows to confirm the result of correction. Per Day [s] 86393 86399.9 *1. Use a high-accuracy frequency counter of 7 digits or more. Caution Measure the oscillation frequency under the usage conditions. Seiko Instruments Inc. 27 2-WIRE REAL-TIME CLOCK S-35392A Serial Interface Rev.1.3_00 The S-35392A receives various commands via I2C-bus serial interface to Read/Write data. Regarding transmission is as follows. 1. Start condition A start condition is when the SDA line changes “H” to “L” when the SCL line is in “H”, so that the access starts. 2. Stop condition A stop condition is when the SDA line changes “L” to “H” when the SCL line is in “H”, and the access stops, so that the S-35392A gets standby. tSU.STA tHD.STA tSU.STO SCL SDA Start condition Figure 28 Start/Stop Conditions Stop condition 3. Data transfer and acknowledgment signal Data transmission is performed for every 1-byte, after detecting a start condition. Transmit data while the SCL line is in “L”, and be careful of spec of tSU.DAT and tHD. DAT when changing the SDA line. If the SDA line changes while the SCL line is in “H”, the data will be recognized as start/stop condition in spite of data transmission. Note that by this case, the access will be interrupted. During data transmission, every moment receiving 1-byte data, the devices which work for receiving data send an acknowledgment signal back. For example, as seen in Figure 29, in case that the S-35392A is the device working for receiving data and the master device is the one working for sending data; when the 8-bit clock pulse falls, the master device releases the SDA line. After that, the S-35392A sends an acknowledgment signal back, and set the SDA line to “L” at the 9-bit clock pulse. The S-35392A does not output an acknowledgment signal is that the access is not being done regularly. SCL (Input from S-35392A) tSU.DAT SDA (Output from master device) 1 tHD.DAT 8 9 SDA is released High-Z Output acknowledgment (“L” active) SDA (Output from S-35392A) High-Z Start condition tPD Figure 29 Output Timing of Acknowledgment Signal 28 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A The followings are Read/Write in the S-35392A. (1) Data Read in S-35392A After detecting a start condition, the S-35392A receives device code and command. The S-35392A enters the Read-data mode by the Read/Write bit “1”. The data is output from B7 in 1-byte. Input an acknowledgment signal from the master device every moment that the S-35392A outputs 1-byte data. However, do not input an acknowledgment signal (input NO_ACK) for the last data-byte output from the master device. This procedure notifies the completion of Read. Next, input a stop condition to the S-35392A to finish access. 1-byte data 1 9 18 SCL R/W NO_ACK START STOP ACK SDA 0 110 000 1 Device code + command B7 B0 : Output from S-35392A : Input from master device Input NO_ACK after the 1st byte of data has been output. Figure 30 Example of Data Read 1 (1-Byte Data Register) 3-byte data 1 9 18 27 36 SCL R/W START STOP NO_ACK ACK ACK SDA 0 11 00 1 11 ACK Device code + command B7 B0 B7 B0 B7 B0 : Output from S-35392A : Input from master device Input NO_ACK after the 3rd byte of data has been output. Figure 31 Example of Data Read 2 (3-Byte Data Register) Seiko Instruments Inc. 29 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 (2) Data Write in S-35392A After detecting a start condition, S-35392A receives device code and command. The S-35392A enters the Write-data mode by the Read/Write bit “0”. Input data from B7 to B0 in 1-byte. The S-35392A outputs an acknowledgment signal (“L”) every moment that 1-byte data is input. After receiving the acknowledgment signal which is for the last byte-data, input a stop condition to the S-35392A to finish access. 1-byte data 1 9 18 SCL R/W START STOP ACK ACK SDA 0 110000 0 B7 Device code + command : Output from S-35392A : Input from master device Figure 32 B0 Example of Data Write 1 (1-Byte Data Register) 3-byte data 1 9 18 27 36 SCL R/W STOP ACK START ACK ACK ACK SDA 0 110011 0 B7 B0 B7 B0 B7 B0 Device code + command : Output from S-35392A : Input from master device Figure 33 Example of Data Read 2 (3-Byte Data Register) 30 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 4. Data access (1) Real-time data 1 access 1 9 18 63 72 SCL R/W STOP START ACK ACK ACK SDA 0 11 00 1 0 ACK*1 *2 *2 Device code + command I/O mode switching B7 B0 Year data B7 B0 Second data I/O mode switching *1. Set NO_ACK = 1 in Read. *2. Transmit ACK = 0 from the master device to the S-35392A in Read. Figure 34 (2) Real-time data 2 access 1 9 18 27 36 Real-Time Data 1 Access SCL R/W START STOP ACK*2 ACK ACK*2 SDA 0 1100 11 ACK*1 Device code + command I/O mode switching B7 Hour data B0 B7 B0 B7 B0 Minute data Second data I/O mode switching *1. *2. Set NO_ACK = 1 in Read. Transmit ACK = 0 from the master device to the S-35392A in Read. Figure 35 Real-Time Data 2 Access (3) Status register 1 access and status register 2 access 1 9 18 SCL *1 START R/W STOP ACK ACK*2 SDA 0 11000 Device code + command I/O mode switching B7 B0 Status data I/O mode switching *1. *2. 0 : Status register 1 selected, 1 : Status register 2 selected Set NO_ACK = 1 in Read. Figure 36 Status Register 1 Access and Status Register 2 Access Seiko Instruments Inc. 31 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 (4) INT1 register access and INT2 register access In Read/Write the INT1 and INT2 registers, data varies depending on the setting of the status register 2. Be sure to Read/Write after setting the status register 2. When setting the alarm by using the status register 2, these registers work as 3-byte alarm time data registers, in other statuses, they work as 1-byte registers. When outputting the user-set frequency, they are the data registers to set up the frequency. Regarding details of each data, refer to “4. INT1 register and INT2 register” in “ Caution Configuration of Register”. Users cannot use both functions of alarm 1 interrupt and the output of user-set frequency simultaneously. 1 9 18 27 36 SCL *1 START R/W STOP ACK*3 ACK*2 ACK ACK*3 SDA 0 11010 Device code + command I/O mode switching B7 Day of the week data B0 B7 Hour data B0 B7 B0 Minute data I/O mode switching *1. *2. *3. 0 : INT1 register selected, 1 : INT2 register selected Set NO_ACK = 1 in Read. Transmit ACK = 0 from the master device to the S-35392A in Read. Figure 37 INT1 Register Access and INT2 Register Access 1 9 18 SCL *1 START R/W STOP ACK*2 ACK SDA 0 11010 Device code + command I/O mode switching *1. *2. B7 B0 Frequency setting data I/O mode switching 0 : INT1 register selected, 1 : INT2 register selected Set NO_ACK = 1 in Read. Figure 38 INT1 Register and INT2 Register (Data Register for Output Frequency) Access 32 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A (5) Clock correction register access 1 9 18 SCL R/W START STOP ACK*1 ACK SDA 0 110110 Device code + command I/O mode switching B7 B0 Clock correction data I/O mode switching *1. Set NO_ACK = 1 in Read. Figure 39 Clock Correction Register Access (6) Free register access 1 9 18 SCL R/W START STOP ACK*1 ACK SDA 0 110111 Device code + command I/O mode switching *1. Set NO_ACK = 1 in Read. Figure 40 B7 B0 Free register data I/O mode switching Free Register Access Seiko Instruments Inc. 33 2-WIRE REAL-TIME CLOCK S-35392A Reset After Communication Interruption Rev.1.3_00 In case of communication interruption in the S-35392A, for example, during communication the power supply voltage drops so that only the master device is reset; the S-35392A does not operate the next procedure because the internal circuit keeps the state prior to interruption. The S-35392A does not have a reset pin so that users usually reset its internal circuit by inputting a stop condition. However, if the SDA line is outputting “L” (during output of acknowledgment signal or Read), the S-35392A does not accept a stop condition from the master device. In this case, users are necessary to finish acknowledgment output or Read the SDA line. Figure 41 shows how to reset. First, input a start condition from the master device (The S-35392A cannot detect a start condition because the SDA line in the S-35392A is outputting “L”). Next, input a clock pulse equivalent to 7-byte data access (63-clock) from the SCL line. During this, release the SDA line for the master device. By this procedure, SDA I/O before interruption is finished, so that the SDA line in the S-35392A is released. After that, inputting a stop condition resets the internal circuit so that restore the regular communication. This reset procedure is recommended to perform at initialization of the system after rising the master device’s power supply voltage. Start condition 1 Stop condition 63 Clocks equivalent to 7-byte data access 2 8 9 62 SCL SDA (Output from master device) SDA (Output from S-35392A) SDA “L” “L” or High-Z High-Z “L” “L” or High-Z Figure 41 How to Reset 34 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A Flowchart of Initialization at Power-on and Example of Real-time Data Set-up Figure 42 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. START Power-on Wait for 0.5 s Read status register 1 NO POC = 1 YES Initialize (status register 1 B7 = 1) Initialization after power-on Read status register 1 NO POC = 0 YES BLD = 0 YES NO Set 24-hour/12-hour display to status register 1 Read status register 1 NG Confirm data in status register 1 OK Set real-time data 1 Example of real-time data setting Read real-time data 1 Read status register 2 NO TEST = 0 YES END Figure 42 Example of Initialization Flowchart Seiko Instruments Inc. 35 2-WIRE REAL-TIME CLOCK S-35392A Examples of Application Circuits 10 kΩ 32KO VDD S-35392A VSS SDA SCL XOUT INT2 1 kΩ 1 kΩ CPU VCC Rev.1.3_00 VCC 10 kΩ System power supply XIN VSS Cg Caution 1. 2. 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. Start communication under stable condition after power-on the power supply in the system. Figure 43 Application Circuit 1 10 kΩ 32KO VDD S-35392A VSS XIN XOUT INT2 1 kΩ 1 kΩ CPU 10 kΩ VCC System power supply SDA SCL VSS Cg Caution Start communication under stable condition after power-on the power supply in the system. Figure 44 Caution Application Circuit 2 Set the constants after performing The above connection diagrams do not guarantee operation. sufficient evaluation using the actual application. 36 Seiko Instruments Inc. Rev.1.3_00 Adjustment of Oscillation Frequency 1. Configuration of oscillator 2-WIRE REAL-TIME CLOCK S-35392A Since crystal oscillation is sensitive to external noise (the clock accuracy is affected), the following measures are essential for optimizing the oscillation configuration. (1) (2) (3) (4) (5) Place the S-35392A, crystal oscillator, and external capacitor (Cg) as close to each other as possible. Increase the insulation resistance between pins and the substrate wiring patterns of XIN and XOUT. Do not place any signal or power lines close to the oscillator. Locating the GND layer immediately below the oscillator is recommended. Locate the bypass capacitor adjacent to the power supply pin of the S-35392A. Parasitic capacitance*3 XIN Rf Cg Crystal oscillator: 32.768 kHz CL = 6 pF*1 Cg = None*2 to 9.1 pF Parasitic capacitance*3 XOUT Cd Rd Oscillator internal constant standard values: Rf = 100 MΩ Rd = 100 kΩ Cd = 8 pF S-35392A *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 45 Connection Diagram 1 1 Crystal oscillator 2 XOUT 3 XIN 4 VSS Cg S-35392A 8 7 6 5 Locate the GND layer in the layer immediately below Figure 46 Caution Connection Diagram 2 1. When using the crystal oscillator with a CL exceeding the rated value (7 pF) (e.g : CL = 12.5 pF), oscillation operation may become unstable. Use a crystal oscillator with a CL value of 6 pF or 7 pF. 2. Oscillation characteristics is subject to the variation of each component such as substrate parasitic capacitance, parasitic resistance, crystal oscillator, and Cg. When configuring an oscillator, pay sufficient attention for them. Seiko Instruments Inc. 37 2-WIRE REAL-TIME CLOCK S-35392A Rev.1.3_00 2. Measurement of oscillation frequency When the S-35392A is turned on, a signal of 32.768 kHz is output from the 32KO pin. Turn the power on and measure the signal with a frequency counter following the circuit configuration shown in Figure 47. Remark If the error range is ±1 ppm in relation to 32.768 kHz, the time is shifted by approximately 2.6 seconds per month (calculated using the following expression). –6 10 (1 ppm) × 60 seconds × 60 minutes × 24 hours × 30 days = 2.592 seconds VDD 1 kΩ 1 kΩ SDA SCL S-35392A XOUT 32KO Open or pull-up INT2 VSS Frequency counter XIN Cg 10 kΩ Figure 47 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. 38 Seiko Instruments Inc. Rev.1.3_00 2-WIRE REAL-TIME CLOCK S-35392A 3. (1) Adjustment of oscillation frequency 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 Select a crystal oscillator*1 Variable capacitance Fixed capacitor YES Trimmer capacitor Set to center of variable capacitance*3 NO Set Cg NO Cg in specification Frequency Change Cg NO YES Optimal value*2 YES Make fine adjustment of frequency using variable capacitance NO YES END *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 48 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. Seiko Instruments Inc. 39 2-WIRE REAL-TIME CLOCK S-35392A Product Name Structure S-35392A I8T1 G Rev.1.3_00 Package name (abbreviation) and IC packing specification 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. 40 Seiko Instruments Inc. Rev.1.3_00 Characteristics (Typical Data) (1) Standby current vs. VDD characteristics Ta = 25°C, CL = 6 pF 1.0 0.8 0.6 0.4 0.2 0 0 1 2-WIRE REAL-TIME CLOCK S-35392A (2) Current consumption vs. Input clock characteristics Ta = 25°C, CL = 6 pF 50 45 40 35 30 25 20 15 10 5 0 VDD = 3.0 V VDD = 5.0 V IDD1 [µA] IDD2 [µA] 2 3 VDD [V] 4 5 6 0 100 200 300 400 SCL frequency [kHz] 500 (3) Standby current vs. Temperature characteristics CL = 6 pF 1.0 0.9 0.8 0.7 IDD1 0.5 [µA] 0.4 0.3 0.2 0.1 0 −40 −25 0 25 Ta [°C] 50 75 85 0.6 VDD = 3.0 V VDD = 5.0 V (4) Standby current vs. Cg characteristics Ta = 25°C, CL = 6 pF 1.0 0.9 0.8 0.7 IDD1 0.5 [µA] 0.4 0.3 0.2 0.1 0 0 2 4 6 Cg [pF] 8 10 0.6 VDD = 5.0 V VDD = 3.0 V (5) Oscillation frequency vs. Cg characteristics Ta = 25°C, CL = 6 pF 100 80 60 40 ∆f/f [ppm] 20 0 −20 −40 −60 −80 −100 0 2 4 6 Cg [pF] 8 10 VDD = 5.0 V VDD = 3.0 V (6) Oscillation frequency vs. VDD characteristics Ta = 25°C, CL = 7.5 pF 50 40 30 20 ∆f/f [ppm] 10 0 −10 −20 −30 −40 −50 0 1 2 3 VDD [V] 4 5 6 Seiko Instruments Inc. 41 2-WIRE REAL-TIME CLOCK S-35392A (7) Oscillation frequency vs. Temperature characteristics Cg = 7.5 pF 20 0 −20 −40 ∆f/f −60 [ppm] −80 −100 −120 −140 −40 −25 0 25 Ta [°C] 50 75 85 VDD = 3.0 V VDD = 5.0 V Rev.1.3_00 (8) Oscillation start time vs. Cg characteristics Ta = 25°C 500 450 400 350 300 tSTA 250 [ms] 200 150 100 50 0 0 2 4 6 Cg [pF] 8 10 VDD = 5.0 V VDD = 3.0 V (9) Output current characteristics 1 (VOUT vs. IOL1) 32KO pin, INT2 pin, Ta = 25°C 50 40 VDD = 5.0 V IOL1 [mA] 30 20 10 0 (10) Output current characteristics 2 (VOUT vs. IOL2) SDA pin, Ta = 25°C 50 40 30 20 10 0 VDD = 5.0 V IOL2 [mA] VDD = 3.0 V VDD = 3.0 V 0 1 2 VOUT [V] 3 4 0 0.5 1 1.5 VOUT [V] 2 2.5 (11) BLD detection, release voltage, VDDT (Min) vs. Temperature characteristics CL = 6 pF 1.4 1.2 1.0 BLD [V] 0.8 0.6 VDDT (Min) 0.4 0.2 0 −40 −25 0 25 Ta [°C] 50 75 85 Detection voltage Release voltage 42 Seiko Instruments Inc. 1 .97±0.03 8 7 6 5 1 0.5 2 3 4 0.08 -0.02 +0.05 0.48±0.02 0.2±0.05 No. PH008-A-P-SD-2.0 TITLE No. SCALE UNIT SNT-8A-A-PKG Dimensions PH008-A-P-SD-2.0 mm Seiko Instruments Inc. ø1.5 -0 +0.1 2.0±0.05 4.0±0.1 0.25±0.05 5° 2.25±0.05 ø0.5±0.1 4.0±0.1 0.65±0.05 4 321 5 6 78 Feed direction No. PH008-A-C-SD-1.0 TITLE No. SCALE UNIT SNT-8A-A-Carrier Tape PH008-A-C-SD-1.0 mm Seiko Instruments Inc. 12.5max. Enlarged drawing in the central part ø13±0.2 9.0±0.3 (60°) (60°) No. PH008-A-R-SD-1.0 TITLE No. SCALE UNIT mm SNT-8A-A-Reel PH008-A-R-SD-1.0 QTY. 5,000 Seiko Instruments Inc. 0.52 2.01 0.52 0.3 0.2 0.3 0.2 0.3 0.2 0.3 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. No. PH008-A-L-SD-3.0 TITLE No. SCALE UNIT SNT-8A-A-Land Recommendation PH008-A-L-SD-3.0 mm Seiko Instruments Inc. • • • • • • 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.