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| 12345 RV5C386A Preliminary 9.Jun.99 I2C-Bus Real-Time Clock ICs with Voltage Monitoring Function 1. OUTLINE The RV5C386A is a CMOS real-time clock IC connected to the CPU by two signal lines, SCL and SDA, and configured to perform serial transmission of time and calendar data to the CPU. The periodic interrupt circuit is configured to generate interrupt signals with six selectable interrupts ranging from 0.5 seconds to 1 month. The 2 alarm interrupt circuits generate interrupt signals at preset times. As the oscillation circuit is driven under constant voltage, fluctuation of the oscillator frequency due to supply voltage is small, and the time keeping current is small (TYP. 0.35 A at 3 volts). The oscillation halt sensing circuit can be used to judge the validity of internal data in such events as power-on; The supply voltage monitoring circuit is configured to record a drop in supply voltage below two selectable supply voltage monitoring threshold settings. The 32kHz clock output function (CMOS output) is intended to output sub-clock pulses for the external microcomputer. The 32-kHz clock output can be disabled by certain input pin. The oscillation adjustment circuit is intended to adjust time counts with high precision by correcting deviations in the oscillation frequency of the crystal oscillator. This model comes in an ultra-compact SSOP10G (Pin Pitch 0.5mm, Height1.2mm, 4.0mmx2.9mm). 2. FEATURES * Timekeeping supply voltage ranging from 1.45 to 5.5V * Low power consumption 0.35A TYP (0.8A MAX) at VDD=3V * Only two signal lines (SCL and SDA) required for connection to the CPU. ( I2C-Bus Interface, 400kHz at VDD2.5V, address 7bits) * Time counters (counting hours, minutes, and seconds) and calendar counters (counting years, months, days, and weeks) (in BCD format) * 1900/2000 identification bit for Year 2000 compliance * Interrupt circuit configured to generate interrupt signals (with interrupts ranging from 0.5 seconds to 1 month) to the CPU and provided with an interrupt flag and an interrupt halt * 2 alarm interrupt circuits (Alarm_W for week, hour, and minute alarm settings and Alarm_D for hour and minute alarm settings) * 32-kHz clock circuit (CMOS output, equipped with a control pin) * Oscillation halt sensing circuit which can be used to judge the validity of internal data * Supply voltage monitoring circuit with two supply voltage monitoring threshold settings * Automatic identification of leap years up to the year 2099 * Selectable 12-hour and 24-hour mode settings * Built-in oscillation stabilization capacitors (CG and CD) * High precision oscillation adjustment circuit * CMOS process * Ultra-compact SSOP10G *) I2C-Bus is a trademark of PHILIPS N.V. Purchase of I2C-Bus components of Ricoh Company, LTD. conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system comforms to the I2C standard Specification as definded by Philips. 12345 -1- RV5C386A 3. PIN CONFIGURATION RV5C386A (SSOP10G) 32KOUT SCL SDA /INTRB VSS 1 2 3 4 5 10 9 8 7 6 PRELIMINARY VDD OSCIN OSCOUT CLKC /INTRA TOP VIEW 4. BLOCK DIAGRAM 32KOUT CLKC 32kHz OUTPUT CONTROL COMPARATOR_W ALARM_W REGISTER (MIN,HOUR, WEEK) ALARM_D REGISTER (MIN,HOUR) VOLTAGE DETECT VSS VDD COMPARATOR_D OSCIN OSC OSCOUT DIVIDER CORREC -TION TIME COUNTER DIV (SEC,MIN,HOUR,WEEK,DAY,MONTH,YEAR) OSC DETECT /INTRA INTERRUPT CONTROL ADDRESS DECODER ADDRESS REGISTER SCL I/O CONTROL SDA /INTRB SHIFT REGISTER 12345 -2- PRELIMINARY 5. PIN DESCRIPTION Symbol SCL Item Serial Clock Line Serial Data Line Interrupt Output A Interrupt Output B 32kHz Clock Output Clock control input RV5C386A SDA /INTRA /INTRB 32KOUT CLKC OSCIN OSCOUT VDD VSS Oscillation Circuit Input / Output Positive Power Supply Input Negative Power The VSS pin is grounded. Supply Input Description The SCL pin is used to input clock pulses synchronizing the input and output of data to and from the SDA pin. Allows a maximum input voltage of 5.5 volts regardless of supply voltage. The SDA pin is used to input or output data intended for writing or reading in synchronization with the SCL pin. Up to 5.5v beyond VDD may be input. This pin functions as an Nch open drain output. The /INTRA pin is used to output periodic interrupt signals to the CPU and alarm interrupt (Alarm_D) signals. Disabled at power-on from 0 volts. Nch. open drain output. The /INTRB pin is used to output alarm interrupt (Alarrm_W) signals to the CPU. Disabled at power-on from 0 volts. Nch. open drain output. The 32KOUT pin is used to output 32.768-kHz clock pulses. Enabled at power-on from 0 volts. CMOS output. The output is disabled if the CLKC pin is set to Low or open. The CLKC pin is used to control output of the 32KOUT pin. The clock output is disabled and held low when the pin is set to low or open. Incorporates a pull-down resistor. The OSCIN and OSCOUT pins are used to connect the 32.768-kHz crystal oscillator (with all other oscillation circuit components built into the RV5C386A). The VDD pin is connected to the power supply. 6. ABSOLUTE MAXIMUM RATINGS Symbol VDD VI VO PD Topt Tstg Item Supply Voltage Input Voltage Output Voltage 1 Output Voltage 1 Power Dissipation Operating Temperature Storage Temperature Pin Name SCL, SDA, CLKC SDA, /INTRA, /INTRB 32KOUT Topt = 25C Description -0.3 to +6.5 -0.3 to +6.5 -0.3 to +6.5 -0.3 to VDD+0.3 300 -40 to +85 -55 to +125 (VSS=0V) Unit V V V V mW C C 7. RECOMMENDED OPERATING CONDITIONS Symbol VDD VCLK fXT VPUP Item Supply Voltage Timekeeping Voltage Oscillation Frequency Pull-up Voltage Pin Name (VSS=0V, Topt=-40 to +85C) Min, Typ. Max. Unit 2.0 5.5 V 1.45 5.5 V 32.768 kHz 5.5 V SCL, SDA, /INTRA, /INTRB 12345 -3- RV5C386A 8. DC ELECTRICAL CHARACTERISTICS Symbol VIH VIL IOH IOL1 IOL2 IOL3 IIL ICLKC Item "H" Input Voltage "L" Input Voltage "H" Output Current "L" Output Current Input Leakage Current Pull Down Resistance Input Current Output Off-state Current Time Keeping Current PRELIMINARY (Unless otherwise specified : VSS=0V,VDD=3V,Topt=-40 to +85C) Pin Name Conditions Min. Typ. Max. Unit SCL,SDA, VDD=2.0 to 5.5V 0.8VDD 5.5 CLKC -0.3 0.2VDD V 32KOUT 32KOUT /INTRA, /INTRB SDA SCL CLKC VOH=VDD-0.5V 0.5 1.0 4.0 -1 0.35 -0.5mA mA VOL=0.4V mA VI=5.5V or VSS VDD=5.5V VI=5.5V 1 1.0 A A IOZ SDA, /INTRA, /INTRB VDD VO=5.5V or VSS VDD=5.5V VDD=3V, SCL=SDA=3V, CLKC=VSS Output = OPEN *1) Topt=-30 to +70C -1 1 A A IDD 0.35 0.8 VDETH Supply Voltage Monitoring Voltage "H" Supply Voltage Monitoring Voltage "L" Internal Oscillation Capacitance 1 Internal Oscillation Capacitance 2 VDD 1.90 2.10 2.30 V VDETL CG VDD OSCIN Topt=-30 to +70C 1.45 1.60 12 1.80 V pF OSCOUT 12 CD *1) For Standby Current for outputting 32.768kHz clock pulses from the 32KOUT pin, see, "14.7 Typical Characteristics". 12345 -4- PRELIMINARY RV5C386A 9. AC ELECTRICAL CHARACTERISTICS Unless otherwise specified : VSS=0V,Topt=-40 to +85C Input and Output Conditions : VIH=0.8xVDD,VIL=0.2xVDD,VOH=0.8xVDD,VOL=0.2xVDD,CL=50pF Symbol Item CondiUnit VDD2.0V VDD2.5V tions Min. Typ. Max. Min. Typ. Max. SCL Clock Frequency 100 400 KHz fSCL SCL Clock Low Time 4.7 1.3 s tLOW SCL Clock High Time 4.0 0.6 s tHIGH 4.0 0.6 s tHD;STA Start Condition Hold Time Stop Condition Set Up Time 4.0 0.6 s tSU;STO 4.7 0.6 s tSU;STA Start Condition Set Up Time 250 200 ns tSU;DAT Data Set Up Time 0 0 ns tHD;DAT Data Hold Time 2.0 0.9 s tPL;DAT SDA "L" Stable Time After Falling of SCL SDA off Stable Time 2.0 0.9 s tPZ;DAT After Falling of SCL Rising Time of SCL and 1000 300 ns tR SDA (input) Falling Time of SCL and 300 300 ns tF SDA (input) Spike Width that can be 50 50 ns tSP removed with Input Filter S Sr P SCL tLOW tHIGH tHD;STA tSP SDA(IN) tHD;STA tSU;DAT tHD;DAT tSU;STA tSU;STO SDA(OUT) tPL;DAT S Sr tPZ;DAT P Start Condition Repeated Start Condition Stop Condition 12345 -5- RV5C386A 10. PACKAGE DIMENSIONS RV5C386A (SSOP10G) 2.9+0.3 -0.1 10 6 PRELIMINARY (Unit : mm) 0 to 10 2.80.2 4.00.3 1 0.5 5 1.10.1 0.127 +0.1 -0.05 0.1 0.20.1 0.15 M 11. TAPING SPECIFICATION The RV5C386A has one designated taping direction. The product designation for the taping components is "RV5C386A-E2". T E P0 P2 F W B A P1 D0 W1 0.1 -0.05 +0.1 0.550.2 D1 T2 Pull-Out Directions Unit:mm A 4.4 0.1 B 3.2 0.1 D0 1.5 +0.1 -0 D1 1.5 +0.1 -0 E 1.75 0.1 F 5.5 0.05 P0 4.0 0.1 P1 8.0 0.1 P2 2.0 0.05 T 0.3 0.05 T2 2.0 (MAX) W 12.0 0.3 W1 9.5 12345 -6- PRELIMINARY RV5C386A 12. GENERAL DESCRIPTION (1) Interface with CPU The RV5C386A is connected to the CPU by two signal lines SCL and SDA, through which it reads and writes data from and to the CPU. Since the output of the I/O pin of SDA is open drain, data interfacing with a CPU different supply voltage is possible by applying pull-up resistors on the circuit board. The maximum clock frequency of 400kHz (at VDD2.5V) of SCL enables data transfer in I2C-Bus fast mode. (2) Clock and Calendar Function The RV5C386A reads and writes time data from and to the CPU in units ranging from seconds to the last two digits of the calendar year. The calendar year will automatically be identified as a leap year when its last two digits are a multiple of 4. Also available is the 1900 / 2000 identification bit for Year 2000 compliance. Consequently, leap years up to the year 2099 can automatically be identified as such. *) The year 2000 is a leap year while the year 2100 is not a leap year. (3) Alarm Function The RV5C386A incorporates the alarm interrupt circuit configured to generate interrupt signals to the CPU at preset times. The alarm interrupt circuit allows two types of alarm settings specified by the Alarm_W registers and the Alarm_D registers. The Alarm_W registers allow week, hour, and minute alarm settings including combinations of multiple day-of-week settings such as "Monday, Wednesday, and Friday" and "Saturday and Sunday". The Alarm_D registers allow hour and minute alarm settings. The Alarm_W outputs from /INTRB pin, and the Alarm_D outputs from /INTRA pin. The current /INTRA or /INTRB conditions specified by the flag bits for each alarm function can be checked from the CPU by using a polling function. (4) High-precision Oscillation Adjustment Function The RV5C386A has built-in oscillation stabilization capacitors (CG and CD), which can be connected to an external crystal oscillator to configure an oscillation circuit. To correct deviations in the oscillation frequency of the crystal oscillator, the oscillation adjustment circuit is configured to allow correction of a time count gain or loss (up to 1.5 ppm at 25C) from the CPU within a maximum range of approximately + 189 ppm in increments of approximately 3 ppm. Such oscillation frequency adjustment in each system has the following advantages: * Allows timekeeping with much higher precision than conventional RTCs while using a crystal oscillator with a wide range of precision variations. * Corrects seasonal frequency deviations through seasonal oscillation adjustment. * Allows timekeeping with higher precision particularly with a temperature sensing function out of RTC, through oscillation adjustment in tune with temperature fluctuations. (5) Oscillation Halt Sensing Function and Supply Voltage Monitoring Function The RV5C386A incorporates an oscillation halt sensing circuit equipped with internal registers configured to record any past oscillation halt, thereby identifying whether they are powered on from 0 volts or battery backed-up. As such, the oscillation halt sensing circuit is useful for judging the validity of time data. The RV5C386A also incorporates a supply voltage monitoring circuit equipped with internal registers configured to record any drop in supply voltage below a certain threshold value. Supply voltage monitoring threshold settings can be selected between 2.1 and 1.6 volts through internal register settings. The oscillation halt sensing circuit is configured to confirm the established invalidation of time data in contrast to the supply voltage monitoring circuit intended to confirm the potential invalidation of time data. Further, the supply voltage monitoring circuit can be applied to battery supply voltage monitoring. 12345 -7- RV5C386A PRELIMINARY (6) Periodic Interrupt Function The RV5C386A incorporates the periodic interrupt circuit configured to generate periodic interrupt signals aside from interrupt signals generated by the alarm interrupt circuit for output from the /INTRA pin. Periodic interrupt signals have five selectable frequency settings of 2 Hz (once per 0.5 seconds), 1 Hz (once per 1 second), 1/60 Hz (once per 1 minute), 1/3600 Hz (once per 1 hour), and monthly (the first day of every month). Further, periodic interrupt signals also have two selectable waveforms, a normal pulse form (with a frequency of 2 Hz or 1 Hz) and special form adapted to interruption from the CPU in the level mode (with second, minute, hour, and month interrupts). The condition of periodic interrupt signals can be monitored by using a polling function. (7) 32kHz Clock Output The RV5C386A incorporates a 32-kHz clock circuit configured to generate clock pulses with the oscillation frequency of a 32.768kHz crystal oscillator for output from the 32KOUT pin (CMOS push-pull output). The 32-kHz clock output is enabled and disabled when the CLKC pin is held high, and low or open, respectively. 12345 -8- PRELIMINARY 13. 13.1. FUNCTION DESCRIPTIONS Address Mapping Address A3A2A1A0 RV5C386A Register Name Second Counter Minute Counter Hour Counter Day-of-week Counter Day-of-month Counter Month Counter and Century Bit Year Counter Oscillation Adjustment Register *3) Alarm_W (Minute Register) Alarm_W (Hour Register) Alarm_W (Day-of-week Register) Alarm_D (Minute Register) Alarm_D (Hour Register) Control Register 1 *3) Control Register 2 *3) D7 *2) /1920 Y80 D6 S40 M40 Y40 F6 D5 S20 M20 H20 P/A D20 Y20 F5 0 1 2 3 4 5 6 7 8 9 A B C D E F 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Data D4 S10 M10 H10 D10 MO10 Y10 F4 WM10 WH10 WW4 DM10 DH10 SCRATCH3 XSTP D3 S8 M8 H8 D8 MO8 Y8 F3 WM8 WH8 WW3 DM8 DH8 TEST D2 S4 M4 H4 W4 D4 MO4 Y4 F2 WM4 WH4 WW2 DM4 DH4 CT2 D1 S2 M2 H2 W2 D2 MO2 Y2 F1 WM2 WH2 WW1 DM2 DH2 CT1 D0 S1 M1 H1 W1 D1 MO1 Y1 F0 WM1 WH1 WW0 DM1 DH1 CT0 WM40 WM20 WW6 DM40 WH20 WP/A WW5 DM20 DH20 DP/A /1224 SCRATCH1 WALE DALE VDSL VDET SCRA- CTFG WAFG DAFG TCH2 Notes: * 1) All the data listed above accept both reading and writing. * 2) The data marked with "-" is invalid for writing and reset to 0 for reading. * 3) When the XSTP bit is set to 1 in Control Register 2, all the bits are reset to 0 in Oscillation Adjustment Register, Control Register 1 and Control Register 2 excluding the XSTP bit. 12345 -9- RV5C386A PRELIMINARY 13.2. 13.2.1. Register Settings Control Register 1 (ADDRESS Eh) D7 WALE WALE 0 *) D6 DALE DALE 0 D5 /1224 /1224 0 D4 SCRATCH3 SCRATCH3 0 D3 TEST TEST 0 D2 CT2 CT2 0 D1 CT1 CT1 0 D0 CT0 CT0 0 (For Writing) (For Reading) Default Settings *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. (1) WALE, DALE WALE,DALE 0 1 Alarm_W Enable Bit, Alarm_D Enable Bit Description Disabling the alarm interrupt circuit (under the control of the settings (Default) of the Alarm_W registers and the Alarm_D registers). Enabling the alarm interrupt circuit (under the control of the settings of the Alarm_W registers and the Alarm_D registers) (2) /1224 12-/24-hour Mode Selection Bit Description /1224 0 Selecting the 12-hour mode with a.m. and p.m. indications. (Default) 1 Selecting the 24-hour mode Setting the /12 24 bit to 0 and 1 specifies the 12-hour mode and the 24-hour mode, respectively. 24-hour mode 00 01 02 03 04 05 06 07 08 09 10 11 12-hour mode 12 (AM12) 01 (AM 1) 02 (AM 2) 03 (AM 3) 04 (AM 4) 05 (AM 5) 06 (AM 6) 07 (AM 7) 08 (AM 8) 09 (AM 9) 10 (AM10) 11 (AM11) 24-hour mode 12 13 14 15 16 17 18 19 20 21 22 23 12-hour mode 32 (PM12) 21 (PM 1) 22 (PM 2) 23 (PM 3) 24 (PM 4) 25 (PM 5) 26 (PM 6) 27 (PM 7) 28 (PM 8) 29 (PM 9) 30 (PM10) 31 (PM11) Setting the /1224 bit should precede writing time data (3) SCRATCH3 Scratch Bit 3 SCRATCH3 0 1 Description (Default) The SCRATCH3 bit is intended for scratching and accepts the reading and writing of 0 and 1. The SCRATCH3 bit will be set to 0 when the XSTP bit is set to 1 in the Control Register 2. (4) TEST Test Bit TEST Description 0 Normal operation mode. 1 Test mode. The TEST bit is used only for testing in the factory and should normally be set to 0. (Default) 12345 - 10 - PRELIMINARY (5) CT2,CT1, and CT0 CT2 CT1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 RV5C386A Periodic Interrupt Selection Bits CT0 Description Wave form mode Interrupt Cycle and Falling Timing 0 OFF(H) (Default) 1 Fixed at "L" 0 Pulse Mode *1) 2Hz(Duty50%) 1 Pulse Mode *1) 1Hz(Duty50%) 0 Level Mode *2) Once per 1 second (Synchronized with second counter increment) 1 Level Mode *2) Once per 1 minute (at 00 seconds of every minute) 0 Level Mode *2) Once per hour (at 00 minutes and 00 seconds of every hour) 1 Level Mode *2) Once per month (at 00 hours, 00 minutes, and 00 seconds of first day of every month) *1) Pulse Mode: 2-Hz and 1-Hz clock pulses are output in synchronization with the increment of the second counter as illustrated in the timing chart below. CTFG Bit /INTRA Pin Approx. 92s (Increment of second counter) Rewriting of the second counter In the pulse mode, the increment of the second counter is delayed by approximately 92 s from the falling edge of clock pulses. Consequently, time readings immediately after the falling edge of clock pulses may appear to lag behind the time counts of the real-time clocks by approximately 1 second. Rewriting the second counter will reset the other time counters of less than 1 second, driving the /INTRA pin low. *2) Level Mode: Periodic interrupt signals are output with selectable interrupt cycle settings of 1 second, 1 minute, 1 hour, and 1 month. The increment of the second counter is synchronized with the falling edge of periodic interrupt signals. For example, periodic interrupt signals with an interrupt cycle setting of 1 second are output in synchronization with the increment of the second counter as illustrated in the timing chart below. CTFG Bit /INTRA Pin Setting CTFG bit to 0 (Increment of second counter) (Increment of second counter) Setting CTFG bit to 0 (Increment of second counter) *1), *2) When the oscillation adjustment circuit is used, the interrupt cycle will fluctuate once per 20sec. as follows: Pulse Mode: The "L" period of output pulses will increment or decrement by a maximum of 3.784 ms. For example, 1-Hz clock pulses will have a duty cycle of 50 0.3784%. Level Mode: A periodic interrupt cycle of 1 second will increment or decrement by a maximum of 3.784 ms. 12345 - 11 - RV5C386A 13.2.2. Control Register 2 (Address Fh) D7 VDSL VDSL 0 D6 VDET VDET 0 D5 SCRATCH1 SCRATCH1 0 D4 XSTP XSTP 1 D3 SCRATCH2 SCRATCH2 0 D2 CTFG CTFG 0 D1 WAFG WAFG 0 D0 DAFG DAFG 0 PRELIMINARY (For Writing) (For Reading) Default Settings *) *) Default settings: Default value means read / written values when the XSTP bit is reset due to power-on from 0 volts or supply voltage drop. (1) VDSL Supply Voltage Monitoring Threshold Selection Bit VDSL Description 0 Selecting the supply voltage monitoring threshold setting of 2.1v. 1 Selecting the supply voltage monitoring threshold setting of 1.6v. The VDSL bit is intended to select the supply voltage monitoring threshold settings. (Default) (2) VDET Supply Voltage Monitoring Result Indication Bit VDET Description 0 Indicating supply voltage above the supply voltage monitoring threshold settings. 1 Indicating supply voltage below the supply voltage monitoring threshold settings. (Default) Once the VDET bit is set to 1, the supply voltage monitoring circuit will be disabled while the VDET bit will hold the setting of 1. The VDET bit accepts only the writing of 0, which restarts the supply voltage monitoring circuit. Conversely, setting the VDET bit to 1 causes no event. (3) SCRATCH1 Scratch Bit 1 SCRATCH1 0 1 Description (Default) The SCRATCH1 bit is intended for scratching and accepts the reading and writing of 0 and 1. The SCRATCH1 bit will be set to 0 when the XSTP bit is set to 1 in the Control Register 2. (4) XSTP Oscillation Halt Sensing Bit XSTP Description 0 Sensing a normal condition of oscillation 1 Sensing a halt of oscillation The XSTP bit is for sensing a halt in the oscillation of the crystal oscillator. (Default) * The XSTP bit will be set to 1 once a halt in the oscillation of the crystal oscillator is caused by such events as power-on from 0 volts and a drop in supply voltage. The XSTP bit will hold the setting of 1 even after the restart of oscillation. As such, the XSTP bit can be applied to judge the validity of clock and calendar data after power-on or a drop in supply voltage. * When the XSTP bit is set to 1, all bits will be reset to 0 in the Oscillation Adjustment Register, Control Register 1, and Control Register 2, stopping the output from /INTRA and /INTRB pins and starting the output of 32.768-kHz clock pulses from the 32KOUT pin. * The XSTP bit accepts only the writing of 0, which restarts the oscillation halt sensing circuit. Conversely, setting the XSTP bit to 1 causes no event. * It is recommendable to frequently check the XSTP bit for setting errors or data garbles, which may seriously affect the operation of the RV5C386A. 12345 - 12 - PRELIMINARY (5) SCRATCH2 Scratch Bit 2 SCRATCH2 0 1 RV5C386A Description (Default) The SCRATCH2 bit is intended for scratching and accepts the reading and writing of 0 and 1. The SCRATCH2 bit will be set to 0 when the XSTP bit is set to 1 in the Control Register 2. (6) CTFG Periodic Interrupt Flag Bit CTFG Description 0 Periodic interrupt output = "H" 1 Periodic interrupt output = "L" (Default) The CTFG bit is set to 1 when the periodic interrupt signals are output from the /INTRA pin ("L"). The CTFG bit accepts only the writing of 0 in the level mode, which disables ("H") the /INTRA pin until it is enabled ("L") again in the next interrupt cycle. Conversely, setting the CTFG bit to 1 causes no event. (7) WAFG,DAFG Alarm_W Flag Bit and Alarm_D Flag Bit WAFG,DAFG Description 0 Indicating a mismatch between current time and preset alarm time (Default) 1 Indicating a match between current time and preset alarm time The WAFG and DAFG bits are valid only when the WALE and DALE have the setting of 1, which is caused approximately 61s after any match between current time and preset alarm time specified by the Alarm_W registers and the Alarm_D registers. The WAFG (DAFG) bit accepts only the writing of 0. /INTRB (/INTRA) pin outputs off ("H") when this bit is set to 0. And /INTRB (/INTRA) pin outputs "L" again at the next preset alarm time. Conversely, setting the WAFG and DAFG bits to 1 causes no event. The WAFG and DAFG bits will have the reading of 0 when the alarm interrupt circuit is disabled with the WALE and DALE bits set to 0. The settings of the WAFG and DAFG bits are synchronized with the output of the /INTRB (/INTRA) pin as shown in the timing chart below. Approx. 61s WAFG(DAFG) Bit /INTRB(/INTRA) Pin Writing of 0 to WAFG(DAFG) bit (Match between current time and preset alarm time) (Match between current time and preset alarm time) Writing of 0 to WAFG(DAFG) bit (Match between current time and preset alarm time) Approx. 61s 12345 - 13 - RV5C386A 13.2.3. * Time Counter (Address 0-2h) Second Counter (Address 0h) D7 D6 D5 0 0 * S40 S40 Indefinite PRELIMINARY D4 S10 S10 Indefinite D3 S8 S8 Indefinite D2 S4 S4 Indefinite D1 S2 S2 Indefinite D0 S1 S1 Indefinite S20 S20 Indefinite (For Writing) (For Reading) Default Settings *) Minute Counter (Address 1h) D7 D6 D5 0 0 M40 M40 Indefinite D4 M10 M10 Indefinite D3 M8 M8 Indefinite D2 M4 M4 Indefinite D1 M2 M2 Indefinite D0 M1 M1 Indefinite M20 M20 Indefinite (For Writing) (For Reading) Default Settings *) * Hour Counter (Address 2h) D7 D6 D5 P/A or H20 0 0 P/A or H20 0 0 Indefinite *) Default settings: D4 H10 H10 Indefinite D3 H8 H8 Indefinite D2 H4 H4 Indefinite D1 H2 H2 Indefinite D0 H1 H1 Indefinite (For Writing) (For Reading) Default Settings *) Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. * Time digit display (BCD format) as follows: The second digits range from 00 to 59 and are carried to the minute digit in transition from 59 to 00. The minute digits range from 00 to 59 and are carried to the hour digits in transition from 59 to 00. The hour digits range as shown in "13.2.1. - (2). /1224: 12-/24-hour Mode Selection Bit" and are carried to the day-of-month and day-of-week digits in transition from PM11 to AM12 or from 23 to 00. * Any writing to the second counter resets divider units of less than 1 second. * Any carry from lower digits with the writing of non-existent time may cause the time counters to malfunction. Therefore, such incorrect writing should be replaced with the writing of existent time data. 13.2.4. Day-of-week Counter (Address 3h) D7 0 0 *) D6 0 0 D5 0 0 D4 0 0 D3 0 0 D2 W4 W4 Indefinite D1 W2 W2 Indefinite D0 W1 W1 Indefinite (For Writing) (For Reading) Default Settings *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. * The day-of-week counter is incremented by 1 when the day-of-week digits are carried to the day-ofmonth digits. * Day-of-week display (incremented in septimal notation): (W4, W2, W1) = (0, 0, 0) (0, 0, 1)...(1, 1, 0) (0, 0, 0) * Correspondences between days of the week and the day-of-week digits are user-definable (e.g. Sunday = 0, 0, 0) * The writing of (1, 1, 1) to (W4, W2, W1) is prohibited except when days of the week are unused. 12345 - 14 - PRELIMINARY 13.2.5. * Calendar Counter (Address 4-6h) Day-of-month Counter (Address 4h) D7 D6 D5 D4 0 0 * 0 0 D20 D20 Indefinite RV5C386A D3 D8 D8 Indefinite D2 D4 D4 Indefinite D1 D2 D2 Indefinite D0 D1 D1 Indefinite D10 D10 Indefinite (For Writing) (For Reading) Default Settings *) Month Counter + Century Bit (Address 5h) D7 D6 D5 D4 D3 /1920 /1920 Indefinite D2 MO4 MO4 Indefinite D1 MO2 MO2 Indefinite D0 MO1 MO1 Indefinite 0 0 0 0 MO10 MO10 Indefinite MO8 MO8 Indefinite (For Writing) (For Reading) Default Settings *) * Year Counter (Address 6h) D7 D6 D5 Y80 Y80 Indefinite D4 Y10 Y10 Indefinite D3 Y8 Y8 Indefinite D2 Y4 Y4 Indefinite D1 Y2 Y2 Indefinite D0 Y1 Y1 Indefinite Y40 Y40 Indefinite Y20 Y20 Indefinite (For Writing) (For Reading) Default Settings *) *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. * The calendar counters are configured to display the calendar digits in BCD format by using the automatic calendar function as follows: The day-of-month digits (D20 to D1) range from 1 to 31 for January, March, May, July, August, October, and December; from 1 to 30 for April, June, September, and November; from 1 to 29 for February in leap years; from 1 to 28 for February in ordinary years. The day-of-month digits are carried to the month digits in reversion from the last day of the month to 1. The month digits (MO10 to MO1) range from 1 to 12 and are carried to the year digits in reversion from 12 to 1. The year digits (Y80 to Y1) range from 00 to 99 (00, 04, 08, ..., 92, and 96 in leap years) and are carried to the /1920 digits in reversion from 99 to 00. The /1920 digits cycle between 0 and 1 in reversion from 99 to 00 in the year digits. * Any carry from lower digits with the writing of non-existent calendar data may cause the calendar counters to malfunction. Therefore, such incorrect writing should be replaced with the writing of existent calendar data. 13.2.6. Oscillation Adjustment Register (Address 7h) D7 0 0 *) D6 F6 F6 0 D5 F5 F5 0 D4 F4 F4 0 D3 F3 F3 0 D2 F2 F2 0 D1 F1 F1 0 D0 F0 F0 0 (For Writing) (For Reading) Default Settings *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. 12345 - 15 - RV5C386A PRELIMINARY F6 to F0 bits The Oscillation Adjustment Circuit is configured to change time counts of 1 second on the basis of the settings of the Oscillation Adjustment Register when the second digits read 00, 20, or 40 seconds. Normally, the Second Counter is incremented once per 32768 32.768-kHz clock pulses generated by the crystal oscillator. Writing to the F6 to F0 bits activates the oscillation adjustment circuit. * The Oscillation Adjustment Circuit will not operate with the same timing (00, 20, or 40 seconds) as the timing of writing to the Oscillation Adjustment Register. * The F6 bit setting of 0 causes an increment of time counts by ((F5, F4, F3, F2, F1, F0) - 1) x 2. The F6 bit setting of 1 causes a decrement of time counts by ((/F5, /F4, /F3, /F2, /F1, /F0) + 1) x 2. The settings of "*, 0, 0, 0, 0, 0, *" ("*" representing either "0" or "1") in the F6, F5, F4, F3, F2, F1, and F0 bits cause neither an increment nor decrement of time counts. Example: When the second digits read 00, 20, or 40, the settings of "0, 0, 0, 0, 1, 1, 1" in the F6, F5, F4, F3, F2, F1, and F0 bits cause an increment of the current time counts of 32768 by (7 - 1) x 2 to 32780 (a current time count loss). When the second digits read 00, 20, or 40, the settings of "0, 0, 0, 0, 0, 0, 1" in the F6, F5, F4, F3, F2, F1, and F0 bits cause neither an increment nor a decrement of the current time counts of 32768. When the second digits read 00, 20, or 40, the settings of "1, 1, 1, 1, 1, 1, 0" in the F6, F5, F4, F3, F2, F1, and F0 bits cause a decrement of the current time counts of 32768 by (- 2) x 2 to 32764 (a current time count gain). An increase of two clock pulses once per 20 seconds causes a time count loss of approximately 3 ppm (2 / (32768 x 20 = 3.051 ppm). Conversely, a decrease of two clock pulses once per 20 seconds causes a time count gain of 3 ppm. Consequently, deviations in time counts can be corrected with a precision of 1.5 ppm. Note that the oscillation adjustment circuit is configured to correct deviations in time counts and not the oscillation frequency of the 32.768-kHz clock pulses. For further details, see "14. 2. 4. Oscillation Adjustment Circuit". 13.2.7. * Alarm_W Registers (Address 8-Ah) Alarm_W Minute Register (Address 8h) D7 D6 D5 D4 0 0 WM40 WM40 Indefinite D3 WM8 WM8 Indefinite D2 WM4 WM4 Indefinite D1 WM2 WM2 Indefinite D0 WM1 WM1 Indefinite WM20 WM20 Indefinite WM10 WM10 Indefinite (For Writing) (For Reading) Default Settings *) * Alarm_W Hour Register (Address 9h) D7 D6 D5 D4 0 0 0 0 WH20 WP/A WH20 WP/A Indefinite Indefinite D3 WH8 WH8 Indefinite D2 WH4 WH4 Indefinite D1 WH2 WH2 Indefinite D0 WH1 WH1 Indefinite WH10 WH10 (For Writing) (For Reading) Default Settings *) * Alarm_W Day-of-week Register (Address Ah) D7 D6 D5 D4 D3 0 0 *) D2 WW2 WW2 Indefinite D1 WW1 WW1 Indefinite D0 WW0 WW0 Indefinite WW6 WW6 Indefinite WW5 WW5 Indefinite WW4 WW4 Indefinite WW3 WW3 Indefinite (For Writing) (For Reading) Default Settings *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. * The D5 bit of the Alarm_W Hour Register represents WP/A when the 12-hour mode is selected (0 for a.m. and 1 for p.m.) and WH20 when the 24-hour mode is selected (tens in the hour digits). * The Alarm_W Registers should not have any non-existent alarm time settings. 12345 - 16 - PRELIMINARY RV5C386A (Note that any mismatch between current time and preset alarm time specified by the Alarm_W registers may disable the alarm interrupt circuit.) * When the 12-hour mode is selected, the hour digits read 12 and 32 for 0 a.m. and 0 p.m., respectively. (See "13.2. 1. - (2). /12 * 24: 12-/24-hour Mode Selection Bit"). * WW0 to WW6 correspond to W4, W2, and W1 of the day-of-week counter with settings ranging from (0, 0, 0) to (1, 1, 0). * WW0 to WW6 with respective settings of 0 disable the outputs of the Alarm_W Registers. Example of Alarm Time Setting Alarm Preset alarm time Sun. Mon. Day-of-week Tue. Wed. Th. Fri. Sat. 12-hour mode 10 hr. 1 10 1 24-hour mode 10 1 10 1 hr. min. min. hr. min. min. hr. WW0 WW1 WW2 WW3 WW4 WW5 WW6 00:00 a.m. on all days 1 1 1 1 1 1 1 12000000 01:30 a.m. on all days 1 1 1 1 1 1 1 01300130 11:59 a.m. on all days 1 1 1 1 1 1 1 11591159 00:00 p.m. on Mon. to Fri. 0 1 1 1 1 1 0 32001200 01:30 p.m. on Sun. 1 0 0 0 0 0 0 21301330 11:59 p.m. 0 1 0 1 0 1 0 31592359 on Mon. ,Wed., and Fri. Note that the correspondence between WW0 to WW6 and the days of the week shown in the above table is only an example and not mandatory. 13.2.8. * Alarm_D Register (Address B-Ch) Alarm_D Minute Register (Address Bh) D7 D6 D5 D4 0 0 DM40 DM40 Indefinite D3 DM8 DM8 Indefinite D2 DM4 DM4 Indefinite D1 DM2 DM2 Indefinite D0 DM1 DM1 Indefinite DM20 DM20 Indefinite DM10 DM10 Indefinite (For Writing) (For Reading) Default Settings *) * Alarm_D Hour Register (Address Ch) D7 D6 D5 D4 0 0 *) D3 DH8 DH8 Indefinite D2 DH4 DH4 Indefinite D1 DH2 DH2 Indefinite D0 DH1 DH1 Indefinite 0 0 DH20 DP/A DH20 DP/A Indefinite DH10 DH10 Indefinite (For Writing) (For Reading) Default Settings *) Default settings: Default value means read/written values when the XSTP bit is set to "1" due to power-on from 0 volts or supply voltage drop. * The D5 bit represents DP/A when the 12-hour mode is selected (0 for a.m. and 1 for p.m.) and DH20 when the 24-hour mode is selected (tens in the hour digits). * The Alarm_D registers should not have any non-existent alarm time settings. (Note that any mismatch between current time and preset alarm time specified by the Alarm_D registers may disable the alarm interrupt circuit.) * When the 12-hour mode is selected, the hour digits read 12 and 32 for 0a.m. and 0p.m., respectively. (see "13.2.1. (2) /12 * 24: 12-/24-hour Mode Selection Bit"). 12345 - 17 - RV5C386A 14. 14.1. PRELIMINARY USAGE Interfacing with the CPU The RV5C386A employs the I2C-Bus system to be connected to the CPU via 2-wires. Connection and system of I2C-Bus are described in the following sections. 14.1.1. Connection of I2C-Bus 2-wires, SCL and SDA pins that are connected to I2C-Bus are used for transmit clock pulses and data respectively. All ICs that are connected to these lines are designed that will not be clamped when a voltage beyond supply voltage is applied to input or output pins. Open drain pins are used for output. This construction allows communication of signals between ICs with different supply voltages by adding a pull-up resistor to each signal line as shown in the figure below. Each IC is designed not to affect SCL and SDA signal lines when power to each of these is turned off separately. VDD1 VDD2 VDD3 VDD4 Rp Rp * For data interface, the following conditions must be met: VDD4VDD1 VDD4VDD2 VDD4VDD3 * When the master is one, the microcontroller is ready for driving SCL to "H" and Rp of SCL may not be required. SCL SDA MicroController RV5C386A Other Peripheral Device Cautions on determining Rp resistance, (1) Dropping voltage at Rp due to sum of input current or output current at off conditions on each IC pin connected to the I2C-Bus shall be adequately small. (2) Rising time of each signal be kept short even when all capacity of the bus is driven. (3) Current consumed in I2C-Bus is small compared to the consumption current permitted for the entire system. When all ICs connected to I2C-Bus are CMOS type, condition (1) may usually be ignored since input current and off-state output current is extremely small for the many CMOS type ICs. Thus the maximum resistance of Rp may be determined based on (2), while the minimum on (3) in most cases. In actual cases a resistor may be place between the bus and input/output pins of each IC to improve noise margins in which case the Rp minimum value may be determined by the resistance. Consumption current in the bus to review (3) above may be expressed by the formula below: Bus consumption current (Sum of input current and off state output current of all devices in standby mode ) x Bus standby duration Bus stand-by duration + the Bus operation duration + Supply voltage x Bus operation duration x 2 Rp resistance x 2 x (Bus stand-by duration + bus operation duration) + Supply voltage x Bus capacity x Charging/Discharging times per unit time Operation of "x 2" in the second member denominator in the above formula is derived from assumption that "L" duration of SDA and SCL pins are the half of bus operation duration. "x 2" in the numerator of the same member is because there are two pins of SDA and SCL. The third member, (charging/discharging times per unit time) means number of transition from "H" to "L" of the signal line. 12345 - 18 - PRELIMINARY RV5C386A Calculation example is shown below: Pull-up resistor (Rp) = 10k, Bus capacity = 50pF(both for SCL, SDA), Vdd=3v, In a system with sum of input current and off-state output current of each pin = 0.1A, I2C-Bus is used for 10ms every second while the rest of 990ms in the stand-by mode, In this mode, number of transitions of the SCL pin from "H" to "L" state is 100 while SDA 50, every second. Bus consumption current 0.1Ax990msec 990msec + 10msec 3V x 10msec x 2 10K x 2 x (990msec + 10msec) + + 3V x 50pF x (100 + 50) 0.099A + 3.0A + 0.0225A 3.12A Generally, the second member of the above formula is larger enough than the first and the third members, bus consumption current may be determined by the second member is many cases. 14.1.2. Transmission System of I2C-Bus (1) Start Condition and Stop Condition In I2C-Bus, SDA must be kept at a certain state while SCL is at the "H" state during data transmission as shown below. SCL SDA tHD;DAT tSU;DAT The SCL and SDA pins are at the "H" level when no data transmission is made. Changing the SDA from "H" to "L" when the SCL and the SDA are "H" activates the Start Condition and access is started. Changing the SDA from "L" to "H" when the SCL is "H" activates Stop Condition and accessing stopped. Generation of Start and Stop Conditions are always made by the master (see the figure below). Start Condition SCL Stop Condition SDA tHD;STA tSU;STO (2) Data transmission and its acknowledge After Start condition is entered, data is transmitted by 1byte (8bits). Any bytes of data may be serially transmitted. The receiving side will send an acknowledge signal to the transmission side each time 8bit data is transmitted. The acknowledge signal is sent immediately after falling to "L" of SCL 8bit clock pulses of data is transmitted, by releasing the SDA by the transmission side that has asserted the bus at that time and by turning SDA to "L" by receiving side. When transmission of 1byte data next to preceding 1byte of data is received the receiving side releases the SDA pin at falling edge of the SCL 9bit of clock pulses or when the receiving side switches to the transmission side it starts data transmission. When the master is receiving side, it generates no acknowledge signal after last 1byte of data from the slave to tell the transmitter that data 12345 - 19 - RV5C386A PRELIMINARY transmission has completed. The slave side (transmission side) continues to release the SDA pin so that the master will be able to generate Stop Condition, after falling edge of the SCL 9bit of clock pulses. SCL from the master SDA from the transmission side SDA from the receiving side Start Condition Acknowledge signal 1 2 8 9 (3) Data Transmission Format in I2C-Bus I2C-Bus has no chip enable signal line. In place of it, each device has a 7bit Slave Address allocated. The first 1byte is allocated to this 7bit address and to the command (R/W) for which data transmission direction is designated by the data transmission thereafter. 7bit address is sequentially transmitted from the MSB and 2 and after bytes are read, when 8bit is "H" and when write "L". The Slave Address of the RV5C386A is specified at (0110010). At the end of data transmission / receiving, Stop Condition is generated to complete transmission. However, if start condition is generated without generating Stop Condition, Repeated Start Condition is met and transmission / receiving data may be continue by setting the Slave Address again. Use this procedure when the transmission direction needs to be change during one transmission. Data is written to the slave from the master S Slave Address (0110010) When data is read from the slave immediately after 7bit addressing from the master S Slave Address 0A R/W=0(Write) 1A R/W=1(Read) Data A Data /A P Data A Data AP (0110010) When the transmission direction is to be changed during transmission. Slave Address (0110010) A Data Inform read has been completed by not generate an acknowledge signal to the slave side. S 0A R/W=0(Write) A Data A Sr Salve Address 1 (0110010) Data /A P R/W=1(Read) Inform read has been completed by not generate an acknowledge signal to the slave side. Master to slave S Start Condition P Slave to master Stop Condition A Sr A /A Acknowledge Signal Repeated Start Condition 12345 - 20 - PRELIMINARY RV5C386A 14.1.3. Data Transmission Write Format in the RV5C386A Although the I2C-Bus standard defines a transmission format for the slave allocated for each IC, transmission method of address information in IC is not defined. The RV5C386A transmits data the internal address pointer (4bit) and the Transmission Format Register (4bit) at the 1byte next to one which transmitted a Slave Address and a write command. For write operation only one transmission format is available and (0000) is set to the Transmission Format Register. The 3byte transmits data to the address specified by the internal address pointer written to the 2byte. Internal address pointer setting are automatically incremented for 4byte and after. Note that when the internal address pointer is Fh, it will change to 0h on transmitting the next byte. Example of data writing (When writing to internal address Eh to Fh) R/W=0(Write) S01100100A11100000A Slave Address (0110010) Address Transmission Pointer Format Eh Register 0h Data Writing of data to the internal address Eh A Data Writing of data to the internal address Fh AP Master to slave S A Start Condition A /A Acknowledge signal P Slave to master Stop Condition 12345 - 21 - RV5C386A PRELIMINARY 14.1.4. Data transmission read format of the RV5C386A The RV5C386A allows the following three readout method of data an internal register. 1) The first method to reading data from the internal register is to specify an internal address by setting the internal address pointer and the transmission format register described 14.1.3, generate the Repeated Start Condition (See section 14.1.2-(3)) to change the data transmission direction to perform reading. The internal address pointer is set to Fh when the Stop Condition is met. Therefore, this method of reading allows no insertion of Stop Condition before the Repeated Start Condition. Set 0h to the Transmission Format Register when this method used. Example 1 of Data Read (when data is read from 2h to 4h) R/W=0(Write) Repeated Start Condition R/W=1(Read) S 0 1 1 0 0 1 0 0 A 0 0 1 0 0 0 0 0 A Sr 0 1 1 0 0 1 0 1 A Slave Address (0110010) Address Transmission Pointer2h Format Register0h Slave Address (0110010) Data Reading of data from the internal address 2h A Data Reading of data from the internal address 3h A Data Reading of data from the internal address 4h /A P Master to slave S A Start Condition A /A Acknowledge signal Sr Slave to master Repeated Start Condition P Stop Condition 12345 - 22 - PRELIMINARY RV5C386A 2) The second method to reading data from the internal register is to start reading immediately after writing to the Internal Address Pointer and the Transmission Format Register. Although this method is not based on I2C-Bus standard in a strict sense it still effective to shorten read time to ease load to the master. Set 4h to the transmission format register when this method used. Example 2 of data read (when data is read from internal addresses Eh to 1h) R/W=0(Write) S01100100A1110 0100A Slave Address (0110010) Address Transmission Pointer Format Eh Register4h Data Reading of data from the internal address Eh A Data Reading of data from the internal address Fh A Data Reading of data from the internal address 0h A Data Reading of data from the internal address 1h /A P Master to slave S A Start Condition A /A Acknowledge Signal Slave to Master P Stop Condition 12345 - 23 - RV5C386A PRELIMINARY 3) The third method to reading data from the internal register is to start reading immediately after writing to the Slave Address and R/W bit. Since the Internal Address Pointer is set to Fh by default as described in 1), this method is only effective when reading is started from the Internal Address Fh. Example 3 of data read (when data is read from internal addresses Fh to 3h) R/W=1(Read) S01100101A Slave Address (0110010) Data Reading of data from the Internal Address Fh A Data Reading of data from the Internal Address 0h A Data Reading of data from the Internal Address 1h A Data Reading of data from the Internal Address 2h A Data Reading of data from the Internal Address 3h /A P Master to slave S A Start Condition A /A Acknowledge Signal Slave to master P Stop Condition 12345 - 24 - PRELIMINARY RV5C386A 14.1.5. Data Transmission under Special Condition The RV5C386A holds the clock tentatively for duration from Start Condition to avoid invalid read or write clock on carrying clock. When clock carried during this period, which will be adjusted within approx. 61s from Stop Condition. To prevent invalid read or write, clock shall be made during one transmission operation (from Start Condition to Stop Condition). When 0.5 to 1.0 second elapses after Start Condition, any access to the RV5C386A is automatically released to release tentative hold of the clock, and access from the CPU is forced to be terminated (The same action as made Stop Condition is received: automatic resume function from I2C-Bus interface). Therefore, one access must be complete within 0.5 seconds. The automatic resume function prevents delay in clock even if SCL is stopped from sudden failure of the system during clock read operation. Also a second Start Condition after the first Start Condition and before the Stop Condition is regarded "Repeated Start Condition". Therefore, when 0.5 to 1.0 seconds passed after the first Start Condition, an access to the RV5C386A is automatically released. If access is tried after automatic resume function is activated, no acknowledge signal will be output for writing while FFh will be output for reading. The user shall always be able to access the real-time clock as long as three conditions are met. (1) No Stop Condition shall be generated until clock read/write is started and completed. (2) One cycle read/write operation shall be complete within 0.5 seconds. (3) Do not make Start Condition within 61s from Stop Condition. When clock is carried during the access, which will be adjusted within approx. 61s from Stop Condition. Bad example of reading from seconds to hours (invalid read) (Start Condition) (Read of seconds) (read of minutes) (Stop Condition) (Start Condition) (Read of hour) (Stop Condition) Assuming read was started at 05:59:59 P.M. and while reading seconds and minutes the time advanced to 06:00:00 P.M. At this time second digit is hold so read the read as 05:59:59. Then the RV5C386A confirms (Stop Condition) and carries second digit being hold and the time change to 06:00:00 P.M. Then, when the hour digit is read, it changes to 6. The wrong results of 06:59:59 will be read. 12345 - 25 - RV5C386A 14.2. 14.2.1. Configuration of Oscillation Circuit and Correction of Time Count Deviations Configuration of Oscillation Circuit VDD VDD PRELIMINARY OSCIN RF CG RD CD OSCOUT A 32kHz Typical externally-equipped element X'tal : 32.768kHz (R1=30k typ) (CL=6pF to 8pF) Standard values of internal elements RF 15M typ RD 120k typ CG,CD 12pF typ The oscillation circuit is driven at a constant voltage of approximately 1.2 volts relative to the level of the VSS pin input. As such, it is configured to generate an oscillating waveform with a peak-to-peak voltage on the order of 1.2 volts on the positive side of the VSS pin input. < Considerations in Handling Crystal Oscillators > Generally, crystal oscillators have basic characteristics including an equivalent series resistance (R1) indicating the ease of their oscillation and a load capacitance (CL) indicating the degree of their center frequency. Particularly, crystal oscillators intended for use in the RV5C386A are recommended to have a typical R1 value of 30k and a typical CL value of 6 to 8pF. To confirm these recommended values, contact the manufacturers of crystal oscillators intended for use in these particular models. < Considerations in Installing Components around the Oscillation Circuit > 1) Install the crystal oscillator in the closest possible vicinity to the real-time clock ICs. 2) Avoid laying any signal lines or power lines in the vicinity of the oscillation circuit (particularly in the area marked "A" in the above figure). 3) Apply the highest possible insulation resistance between the OSCIN and OSCOUT pins and the printed circuit board. 4) Avoid using any long parallel lines to wire the OSCIN and OSCOUT pins. 5) Take extreme care not to cause condensation, which leads to various problems such as oscillation halt. < Other Relevant Considerations > 1) For external input of 32.768-kHz clock pulses to the OSCIN pin: DC coupling: Prohibited due to an input level mismatch. AC coupling: Permissible except that the oscillation halt sensing circuit does not guarantee perfect operation because it may cause sensing errors due to such factors as noise. 2) To maintain stable characteristics of the crystal oscillator, avoid driving any other IC through 32.768-kHz clock pulses output from the OSCOUT pin. 12345 - 26 - PRELIMINARY 14.2.2. Measurement of Oscillation Frequency RV5C386A VDD OSCIN 32768Hz OSCOUT CLKC 32KOUT VSS Frequency Counter * 1) The RV5C386A is configured to generate 32.768-kHz clock pulses for output from the 32KOUT pin. * 2) A frequency counter with 6 (more preferably 7) or more digits on the order of 1ppm is recommended for use in the measurement of the oscillation frequency of the oscillation circuit. * 3) The CLKC pin should be connected to the VDD pin as a pull-up resistor. 14.2.3. Adjustment of Oscillation frequency The oscillation frequency of the oscillation circuit can be adjusted by varying procedures depending on the usage of Model RV5C386A in the system into which they are to be built and on the allowable degree of time count errors. The flow chart below serves as a guide to selecting an optimum oscillation frequency adjustment procedure for the relevant system. Start Use 32-kHz clock output? YES YES NO Allowable time count precision on order of oscillation frequency variations of crystal oscillator (*1) plus NO frequency variations of RTC (*2)? (*3) YES Course (A) Course (B) Use 32-kHz clock output without regard to its frequency precision Course (C) NO YES Allowable time count precision on order of oscillation frequency variations of crystal oscillator (*1) plus NO frequency variations of RTC (*2)? (*3) Course (D) * 1) Generally, crystal oscillators for commercial use are classified in terms of their center frequency depending on their load capacitance (CL) and further divided into ranks on the order of 10, 20, and 50ppm depending on the degree of their oscillation frequency variations. * 2) Basically, Model RV5C386A is configured to cause frequency variations on the order of 5 to 10ppm at normal temperature. * 3) Time count precision as referred to in the above flow chart is applicable to normal temperature and actually affected by the temperature characteristics and other properties of crystal oscillators. 12345 - 27 - RV5C386A PRELIMINARY Course (A) When the time count precision of each RTC is not to be adjusted, the crystal oscillator intended for use in that RTC may have any CL value requiring no presetting. The crystal oscillator may be subject to frequency variations which are selectable within the allowable range of time count precision. Several crystal oscillators and RTCs should be used to find the center frequency of the crystal oscillators by the method described in "14.2. 2. Measurement of Oscillation Frequency" and then calculate an appropriate oscillation adjustment value by the method described in "14.2. 4. Oscillation Adjustment Circuit" for writing this value to the RV5C386A. Course (B) When the time count precision of each RTC is to be adjusted within the oscillation frequency variations of the crystal oscillator plus the frequency variations of the real-time clock ICs, it becomes necessary to correct deviations in the time count of each RTC by the method described in "14.2.4. Oscillation Adjustment Circuit". Such oscillation adjustment provides crystal oscillators with a wider range of allowable settings of their oscillation frequency variations and their CL values. The real-time clock IC and the crystal oscillator intended for use in that real-time clock IC should be used to find the center frequency of the crystal oscillator by the method described in "14.2.2. Measurement of Oscillation Frequency" and then confirm the center frequency thus found to fall within the range adjustable by the oscillation adjustment circuit before adjusting the oscillation frequency of the oscillation circuit. At normal temperature, the oscillation frequency of the oscillator circuit can be adjusted by up to approximately 1.5ppm. Course (C) Course (C) together with Course (D) requires adjusting the time count precision of each RTC as well as the frequency of 32.768-kHz clock pulses output from the 32KOUT pin. Normally, the oscillation frequency of the crystal oscillator intended for use in the RTCs should be adjusted by adjusting the oscillation stabilizing capacitors CG and CD connected to both ends of the crystal oscillator. The RV5C386A, which incorporate the CG and the CD, require adjusting the oscillation frequency of the crystal oscillator through its CL value. Generally, the relationship between the CL value and the CG and CD values can be represented by the following equation: CL = (CG x CD)/(CG + CD) + CS where "CS" represents the floating capacity of the printed circuit board. The crystal oscillator intended for use in the RV5C386A is recommended to have the CL value on the order of 6 to 8pF. Its oscillation frequency should be measured by the method described in "14.2.2. Measurement of Oscillation Frequency". Any crystal oscillator found to have an excessively high or low oscillation frequency (causing a time count gain or loss, respectively) should be replaced with another one having a smaller and greater CL value, respectively until another one having an optimum CL value is selected. In this case, the bit settings disabling the oscillation adjustment circuit (see "14.2.4. Oscillation Adjustment Circuit") should be written to the oscillation adjustment register. Incidentally, the high oscillation frequency of the crystal oscillator can also be adjusted by adding an external oscillation stabilization capacitor CGOUT as illustrated in the diagram below. VDD VDD *1) The CGOUT should have a capacitance ranging from 0 to 15 pF. OSCIN RF CG RD CD 32kHz OSCOUT CGout *1) Course (D) It is necessary to select the crystal oscillator in the same manner as in Course (C) as well as correct errors in the time count of each RTC in the same manner as in Course (B) by the method described in "14.2.4. Oscillation Adjustment Circuit". 12345 - 28 - PRELIMINARY RV5C386A 14.2.4. Oscillation Adjustment Circuit The oscillation adjustment circuit can be used to correct a time count gain or loss with high precision by varying the number of 1-second clock pulses once per 20 seconds. When such oscillation adjustment is not to be made, the oscillation adjustment circuit can be disabled by writing the settings of "*, 0, 0, 0, 0, 0, *" ("*" representing "0" or "1") to the F6, F5, F4, F3, F2, F1, and F0 bits in the oscillation adjustment circuit. Conversely, when such oscillation adjustment is to be made, an appropriate oscillation adjustment value can be calculated by the equation below for writing to the oscillation adjustment circuit. (1) When Oscillation Frequency (* 1) Is Higher Than Target Frequency (* 2) (Causing Time Count Gain) Oscillation adjustment value (*3) = (Oscillation frequency - Target Frequency + 0.1) Oscillation frequency x 3.051 x 10-6 (Oscillation Frequency - Target Frequency) x 10 + 1 * 1) Oscillation frequency: Frequency of clock pulse output from the 32KOUT pin at normal temperature in the manner described in "14.2.2. Measurement of Oscillation Frequency". * 2) Target frequency: Desired frequency to be set. Generally, a 32.768-kHz crystal oscillator has such temperature characteristics as to have the highest oscillation frequency at normal temperature. Consequently, the crystal oscillator is recommended to have target frequency settings on the order of 32.768 to 32.76810 kHz (+3.05ppm relative to 32.768 kHz). Note that the target frequency differs depending on the environment or location where the equipment incorporating the RTC is expected to be operated. * 3) Oscillation adjustment value: Value that is to be finally written to the F0 to F6 bits in the Oscillation Adjustment Register and is represented in 7-bit coded decimal notation. (2) When Oscillation Frequency Is Equal To Target Frequency (Causing Time Count neither Gain nor Loss) Oscillation adjustment value = 0, +1, -64, or -63 (3) When Oscillation Frequency Is Lower Than Target Frequency (Causing Time Count Loss) Oscillation adjustment value = (Oscillation frequency - Target Frequency) Oscillation frequency x 3.051 x 10-6 (Oscillation Frequency - Target Frequency) x 10 Oscillation adjustment value calculations are exemplified below (A) For an oscillation frequency = 32768.85Hz and a target frequency = 32768.05Hz -6 Oscillation adjustment value = (32768.85 - 32768.05 + 0.1) / (32768.85 x 3.051 x 10 ) (32768.85 - 32768.05) x 10 + 1 = 9.001 9 In this instance, write the settings (F6,F5,F4,F3,F2,F1,F0)=(0,0,0,1,0,0,1) in the oscillation adjustment register. Thus, an appropriate oscillation adjustment value in the presence of any time count gain represents a distance from 01h. (B) For an oscillation frequency = 32763.95Hz and a target frequency = 32768.05Hz Oscillation adjustment value = (32763.95 - 32768.05) / (32763.95 x 3.051 x 10-6) (32763.95 - 32768.05) x 10 = -41.015 -41 To represent an oscillation adjustment value of - 41 in 7-bit coded decimal notation, subtract 41 (29h) from 128 (80h) to obtain 57h. In this instance, write the settings of (F6,F5,F4,F3,F2,F1,F0) = (1,0,1,0,1,1,1) in the oscillation adjustment register. Thus, an appropriate oscillation adjustment value in the presence of any time count loss represents a distance from 80h. Oscillation adjustment involves an adjustment differential of approximately 1.5ppm from the target frequency at normal temperature. 12345 - 29 - RV5C386A PRELIMINARY Notes: 1) Oscillation adjustment does not affect the frequency of 32.768-kHz clock pulses output from the 32KOUT pin. 2) Oscillation adjustment value range: When the oscillation frequency is higher than the target frequency (causing a time count gain), an appropriate time count gain ranges from -3.05ppm to -189.2ppm with the settings of "0, 0, 0, 0, 0, 1, 0" to "0, 1, 1, 1, 1, 1, 1" written to the F6, F5, F4, F3, F2, F1, and F0 bits in the oscillation adjustment register, thus allowing correction of a time count gain of up to +189.2ppm. Conversely, when the oscillation frequency is lower than the target frequency (causing a time count loss), an appropriate time count gain ranges from +3.05ppm to +189.2ppm with the settings of "1, 1, 1, 1, 1, 1, 1" to "1, 0, 0, 0, 0, 1, 0" written to the F6, F5, F4, F3, F2, F1, and F0 bits in the oscillation adjustment register, thus allowing correction of a time count loss of up to -189.2ppm. 14.3. Oscillation Halt Sensing and Supply Voltage Monitoring The oscillation halt sensing circuit is configured to record a halt on oscillation by 32.768-kHz clock pulses. The supply voltage monitoring circuit is configured to record a drop in supply voltage below a threshold voltage of 2.1 or 1.6v. Both the flag bits of these circuits (i.e. the XSTP bit for the former and the VDET bit for the latter) in the control register 2, are maintained "1" until they are reset by the setting of 0 in the same bits. When the XSTP bit is set to 1 for the oscillation halt sensing circuit, the VDET bit is reset to 0 for the supply voltage monitoring circuit. The relationship between the XSTP and VDET bits is shown in the table below. XSTP 0 0 1 VDET 0 1 * Conditions of supply voltage and oscillation No drop in supply voltage below threshold voltage and no halt in oscillation Drop in supply voltage below threshold voltage and no halt in oscillation Halt on oscillation Threshold voltage (2.1V or 1.6V) Supply voltage 32768Hz Oscillation Normal voltage detector Supply voltage monitoring (VDET) Oscillation halt sensing (XSTP) Internal initialization period (1 to 2 sec.) XSTP,VDET0 VDET0 XSTP,VDET0 When the XSTP bit is set to 1 in the control register 2, the F6 to F0, WALE, DALE, /1224, SCRATCH3, TEST, CT2, CT1, CT0, VDSL, VDET, SCRATCH1, SCRATCH2, CTFG, WAFG, and DAFG bits are reset to 0 in the oscillation adjustment register, the control register 1, and the control register 2. The XSTP bit is also set to 1 at power-on from 0 volts. Note that the XSTP bit may be locked upon instantaneous power-down. 12345 - 30 - PRELIMINARY RV5C386A < Considerations in Using Oscillation Halt Sensing Circuit > Be sure to prevent the oscillation halt sensing circuit from malfunctioning by preventing the following: 1) Instantaneous power-down on the VDD 2) Condensation on the crystal oscillator 3) On-board noise to the crystal oscillator 4) Applying to individual pins voltage exceeding their respective maximum ratings In particular, note that the XSTP bit may fail to be set to 1 in the presence of any applied supply voltage as illustrated below in such events as backup battery installation. Further, give special considerations to prevent excessive chattering in the oscillation halt sensing circuit. VDD < Supply Voltage Sensing Circuit > The Supply voltage monitoring circuit is configured to conduct a sampling operation during an interval of 7.8ms per second to check for a drop in supply voltage below a threshold voltage of 2.1 or 1.6v for the VDSL bit setting of 0 (the default setting) or 1, respectively, in the Control Register 2, thus minimizing supply current requirements as illustrated in the timing chart below. This circuit suspends a sampling operation once the VDET bit is set to 1 in the Control Register 2. VDD Threshold voltage of 2.1 or 1.6v XSTP Internal initialization period (1 to 2 sec.) Sampling operation by supply voltage monitoring circuit 7.8ms 1s VDET (D6 at Address Fh) XSTP, VDET0 VDET0 12345 - 31 - RV5C386A 14.4. PRELIMINARY Alarm and Periodic Interrupt The RV5C386A incorporates the alarm interrupt circuit and the periodic interrupt circuit that are configured to generate alarm signals and periodic interrupt signals, respectively, for output from the /INTRA or /INTRB pins as described below. (1) Alarm Interrupt Circuit The alarm interrupt circuit is configured to generate alarm signals for output from the /INTRA or /INTRB, which is driven low (enabled) upon the occurrence of a match between current time read by the time counters (the day-of-week, hour, and minute counters) and alarm time preset by the alarm registers (the Alarm_W registers intended for the day-of-week, hour, and minute digit settings and the Alarm_D registers intended for the hour and minute digit settings). The Alarm_W is output from the /INTRB, and the Alarm_D is output from /INTRA. (2) Periodic Interrupt Circuit The periodic interrupt circuit is configured to generate either clock pulses in the pulse mode or interrupt signals in the level mode for output from the /INTRA pin depending on the CT2, CT1, and CT0 bit settings in the control register 1. The above two types of interrupt signals are monitored by the flag bits (i.e. the WAFG, DAFG, and CTFG bits in the Control Register 2) and enabled or disabled by the enable bits (i.e. the WALE, DALE, CT2, CT1, and CT0 bits in the Control Register 1) as listed in the table below. Flag bits WAFG (D1 at Address Fh) DAFG (D0 at Address Fh) CTFG (D2 at Address Fh) Enable bits WALE (D7 at Address Eh) DALE (D6 at Address Eh) CT2=CT1=CT0=0 (These bit setting of "0" disable the Periodic Interrupt) (D2 to D0 at Address Eh) Output Pin /INTRB /INTRA /INTRA Alarm_W Alarm_D Peridic Interrupt * At power-on, when the WALE, DALE, CT2, CT1, and CT0 bits are set to 0 in the Control Register 1, the /INTRA and /INTRB pins are driven high (disabled). * When two types of interrupt signals are output simultaneously from the /INTRA pin, the output from the /INTRA pin becomes an OR waveform of their negative logic. Example: Combined Output to /INTRA Pin Under Control of /ALARM_D and Periodic Interrupt /Alarm_D Periodic Interrupt /INTRA In this event, which type of interrupt signal is output from the /INTRA pin can be confirmed by reading the DAFG, and CTFG bit settings in the Control Register 2. 14.4.1. Alarm Interrupt The alarm interrupt circuit is controlled by the enable bits (i.e. the WALE and DALE bits in the Control Register 1) and the flag bits (i.e. the WAFG and DAFG bits in the Control Register 2). The enable bits can be used to enable this circuit when set to 1 and to disable it when set to 0. When intended for reading, the flag bits can be used to monitor alarm interrupt signals. When intended for writing, the flag bits will cause no event when set to 1 and will drive high (disable) the alarm interrupt circuit when set to 0. The enable bits will not be affected even when the flag bits are set to 0. In this event, therefore, the alarm interrupt circuit will continue to function until it is driven low (enabled) upon the next occurrence of a match between current time and preset alarm time. 12345 - 32 - PRELIMINARY RV5C386A The alarm function can be set by presetting desired alarm time in the alarm registers (the Alarm_W Registers for the day-of-week digit settings and both the Alarm_W Registers and the Alarm_D Registers for the hour and minute digit settings) with the WALE and DALE bits once set to 0 and then to 1 in the Control Register 1. Note that the WALE and DALE bits should be once set to 0 in order to disable the alarm interrupt circuit upon the coincidental occurrence of a match between current time and preset alarm time in the process of setting the alarm function. Interval (1min.) during which a match between current time and preset alarm time occurs Max.61.1s /INTRB (/INTRA) WALE1 current time = WALE0 preset alarm time (DALE) (DALE) WALE1 (DALE) WALE0 current time = preset alarm time (DALE) /INTRB (/INTRA) WALE1 current time = preset alarm time (DALE) WAFG0 (DAFG) current time = preset alarm time 14.4.2. Periodic Interrupt Setting of the periodic selection bits (CT2 to CT0) enables periodic interrupt to the CPU. There are two waveform modes: pulse mode and level mode. In the pulse mode, the output has a waveform duty cycle of around 50%. In the level mode, the output is cyclically driven low and, when the CTFG bit is set to 0, the output is return to High (OFF). CT2 0 0 0 0 1 1 1 1 CT1 0 0 1 1 0 0 1 1 CT0 0 1 0 1 0 1 0 1 Wave form mode Pulse Mode *1) Pulse Mode *1) Level Mode *2) Level Mode *2) Level Mode *2) Level Mode *2) Description Interrupt Cycle and Falling Timing OFF(H) (Default) Fixed at "L" 2Hz(Duty50%) 1Hz(Duty50%) Once per 1 second (Synchronized with Second counter increment) Once per 1 minute (at 00 seconds of every Minute) Once per hour (at 00 minutes and 00 Seconds of every hour) Once per month (at 00 hours, 00 minutes, and 00 seconds of first day of every month) *1) Pulse Mode: 2-Hz and 1-Hz clock pulses are output in synchronization with the increment of the second counter as illustrated in the timing chart below. CTFG Bit /INTRA Pin Approx. 92s (Increment of second counter) Rewriting of the second counter 12345 - 33 - RV5C386A PRELIMINARY In the pulse mode, the increment of the second counter is delayed by approximately 92 s from the falling edge of clock pulses. Consequently, time readings immediately after the falling edge of clock pulses may appear to lag behind the time counts of the real-time clocks by approximately 1 second. Rewriting the second counter will reset the other time counters of less than 1 second, driving the /INTRA pin low. *2) Level Mode: Periodic interrupt signals are output with selectable interrupt cycle settings of 1 second, 1 minute, 1 hour, and 1 month. The increment of the second counter is synchronized with the falling edge of periodic interrupt signals. For example, periodic interrupt signals with an interrupt cycle setting of 1 second are output in synchronization with the increment of the second counter as illustrated in the timing chart below. CTFG Bit /INTRA Pin Setting CTFG bit to 0 (Increment of second counter) (Increment of second counter) Setting CTFG bit to 0 (Increment of second counter) *1), *2) When the oscillation adjustment circuit is used, the interrupt cycle will fluctuate once per 20sec. as follows: Pulse Mode: The "L" period of output pulses will increment or decrement by a maximum of 3.784ms. For example, 1-Hz clock pulses will have a duty cycle of 50 0.3784%. Level Mode: A periodic interrupt cycle of 1 second will increment or decrement by a maximum of 3.784 ms. 14.5. 32-kHz CLOCK OUTPUT For the RV5C386A, 32.768-kHz clock pulses are output from the 32KOUT pin when the CLKC pin is set to high. If CLKC is set to low or opened, the 32KOUT pin is driven low. For the RV5C386A, the 32KOUT pin output is synchronized with CLKC pin input as illustrated in the timing chart below. CLKC pin 32KOUT pin Max.76.3s 12345 - 34 - PRELIMINARY 14.6. 14.6.1. Typical Applications Typical Power Circuit Configurations RV5C386A Sample circuit configuration 1 *1) System power supply OSCIN OSCOUT VDD 32768Hz Install bypass capacitors for high-frequency and low-frequency applications in parallel in close vicinity to the RV5C386A. *1) VSS Sample circuit configuration 2 System power supply OSCIN OSCOUT VDD 32768Hz *1) When using an OR diode as a power supply for the RV5C386A ensure that voltage exceeding the absolute maximum rating of VDD+0.3v is not applied the 32KOUT pin. *1) VSS 12345 - 35 - RV5C386A PRELIMINARY 14.6.2. Connection of /INTRA and /INTRB Pin The /INTRA and /INTRB pins follow the N-channel open drain output logic and contains no protective diode on the power supply side. As such, it can be connected to a pull-up resistor of up to 5.5 volts regardless of supply voltage. System power supply /INTRA or /INTRB OSCIN OSCOUT VDD VSS 32768Hz A *1) B Backup power supply *1) Depending on whether the /INTRA and /INTRB pins are to be used during battery backup, it should be connected to a pull-up resistor at the following different positions: (1) Position A in the left diagram when it is not to be used during battery backup. (2) Position B in the left diagram when it is to be used during battery backup. 14.6.3. Connection of 32KOUT Pin As the 32KOUT pin is CMOS output, the power supply voltage of the RV5C386A and any devices to be connected to the 32KOUT should be same. When the devices is powered down, the 32KOUT output should be disabled. When the CLKC pin is connected to the system power supply through the pull-up resistor, the pull-up resistor should be 0 to 10k, and the 32KOUT pin should be connect to the host through the resistor (approx. 10k). System power supply CLKC 32KOUT OSCIN Back-up power supply OSCOUT 32768Hz VDD VSS VDD VSS OSCOUT 32768Hz RN5VL XXC CLKC Host 32KOUT OSCIN Approx. 10K Back-up power supply 0 to10K System power supply 12345 - 36 - PRELIMINARY 14.7. Typical Characteristics RV5C386A Test Circuit VDD OSCIN OSCOUT 32KOUT VSS 32768Hz Frequency Counter X'tal: 32.768kHz (R1=30k typ) (CL=6pF to 8pF) Topt: 25C Output: Open Timekeeping Current vs. Supply voltage Timekeeping Current vs. Supply voltage (with no 32-kHz clock output) (with 32-kHz clock output) (SCL,SDA="H", CLKC="L" Output=Open, Topt=25C) (SCL,SDA="H", CLKC="H" Output=Open, Topt=25C) Timekeeping Current IDD (uA) Timekeeping Current IDD(uA) 0 1 2 3 4 5 6 1 0.8 0.6 0.4 0.2 0 Supply Voltage VDD(v) 3 2.5 2 1.5 1 0.5 0 0 1 2 3 4 5 6 Supply Voltage VDD(v) CPU Access Current vs. SCL Clock Frequency (Output=Open,Topt=25C) CPU Access Current IDD(uA) Timekeeping Current vs. Operating Temperature (with no 32-kHz clock output) (SCL,SDA=Open, Output=Open, ) Timekeeping Current IDD(uA) 2 1.5 1 0.5 0 -60 -40 -20 0 20 40 60 80 100 Operating Temperature Topt(C) 20 15 10 5 0 0 100 200 300 400 500 SCL Clock Frequency (kHz) VDD=5v VDD=3v 12345 - 37 - RV5C386A Oscillation Frequency Deviation vs. External CG (VDD=3v,Topt=25C, External CG=0pF as standard) 10 5 0 -5 -10 -15 -20 -25 -30 -35 -40 0 5 10 15 20 External CG (pF) Oscillation Frequency Devitation (ppm) PRELIMINARY Oscillation Frequency Deviation vs. Supply Voltage (Topt=25C,VDD=3v as standard) 5 4 3 2 1 0 -1 -2 -3 -4 -5 0 1 2 3 4 5 6 Supply Voltage VDD(v) Oscillation Frequency Deviation vs. Operating Temperature (VDD=3v, Topt=25C standard) 20 0 -20 -40 -60 -80 -100 -120 -140 -60 -40 -20 0 20 40 60 80 10 0 Operating Temperature Topt(C) Oscillation Frequency Devitation (ppm) Oscillation Start Time vs. Supply Voltage (Topt=25C) Oscillation Start Time (ms) 500 400 300 200 100 0 0 1 2 3 4 5 6 Supply Voltage VDD(v) VOL vs. IOL (SDA, /INTRA, /INTRB Pin) (Topt=25C) 30 25 Input Current to CLKC pin vs. Supply Voltage (Topt=25C) ICLKC(uA) 1 IOL (mA) 20 15 10 5 0 0 0.2 0.4 0.6 0.8 VOL (v) VDD=5v VDD=3v Oscillation Frequency Devitation (ppm) 1 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 6 Supply Voltage VDD(v) 12345 - 38 - PRELIMINARY 14.8. 14.8.1. Typical Software-based Operations Initialization at Power-on Start *1) Power-on *2) XSTP=1? RV5C386A No *3) VDET=0? Yes *4) Yes Set Oscillation Adjustment Register and Control Register 1 and 2, etc. No Warning Back-up Battery Run-down *1) After power-on from 0 volt, the start of oscillation and the process of internal initialization require a time span on the order of 1 to 2sec, so that access should be done after the lapse of this time span or more. *2) The XSTP bit setting of 0 in the Control Register 1 indicates power-on from backup battery and not from 0v. The XSTP bit may fail to be set to 1 in the presence of any excessive chattering in power supply in such events as installing backup battery. Should there be any possibility of this failure occurring, it is recommended to initialize Model RV5C386A RTCs regardless of the current XSTP bit setting. For further details, see "14.3. Oscillation Halt Sensing and Supply Voltage Monitoring". *3) This step is not required when the supply voltage monitoring circuit is not used. *4) This step involves ordinary initialization including the Oscillation Adjustment Register and interrupt cycle settings, etc. 14.8.2. Writing of Time and Calendar Data *1) When writing to clock and calendar counters, do not insert Stop Condition until all times from second to year have been written to prevent error in writing time. (Detailed in "14.1.5. Data Transmission under Special Condition". *2) Any writing to the second counter will reset divider units lower than the second digits. *3) Take care so that process from Start Condition to Stop Condition will be complete within 0.5sec. (Detailed in "14.1.5. Data Transmission under Special Condition". The RV5C386A may also be initialized not at power-on but in the process of writing time and calendar data. *1) Start Condition Write to Time Counter and Calendar Counter *2) Stop Condition *3) 12345 - 39 - RV5C386A 14.8.3. Reading Time and Calendar Data (1) Ordinary Process of Reading Time and Calendar Data PRELIMINARY *1) Start Condition *1) When writing to clock and calendar counters, do not insert Stop Condition until all times from second to year have been written to prevent error in writing time. (Detailed in "14.1.5. Data Transmission under Special Condition". *2) Take care so that process from Start Condition to Stop Condition will be complete within 0.5sec. (Detailed in "14.1.5. Data Transmission under Special Condition". Read from Time Counter and Calendar Counter Start Condition *2) (2) Basic Process of Reading Time and Calendar Data with Periodic Interrupt Function Set Periodic Interrupt Cycle Selection Bits *1) *1) This step is intended to select the level mode as a waveform mode for the periodic interrupt function. *2) This step must be completed within 0.5 second. *3) This step is intended to set the CTFG bit to 0 in the Control Register 2 to cancel an interrupt to the CPU. Generate Interrupt in CPU CTFG=1? No *2) Yes Read from Time Counter and Calendar Counter Other Interrupt Processes *3) Control Register 2 (X1X1X011) 12345 - 40 - PRELIMINARY (3) Applied Process of Reading Time and Calendar Data with Periodic Interrupt Function RV5C386A Time data need not be read from all the time counters when used for such ordinary purposes as time count indication. This applied process can be used to read time and calendar data with substantial reductions in the load involved in such reading. For Time Indication in "Day-of-Month, Day-of-week, Hour, Minute, and Second" Format: Control Register 1 (XXXX0100) Control Register 2 (X1X1X011) *1) Generate interrupt to CPU CTFG=1? No *2) Yes Sec.=00? *1) This step is intended to select the level mode as a waveform mode for the periodic interrupt function. *2) This step must be completed within 0.5 sec. *3) This step is intended to read time data from all the time counters only in the first session of reading time data after writing time data. Other interrupts *4) This step is intended to set the CTFG Processes bit to 0 in the Control Register 2 to cancel an interrupt to the CPU. No *3) Use Previous Min.,Hr., Day,and Day-of-week data Yes Read Min.,Hr.,Day, and Day-of-week Control Register 2 (X1X1X011) *4) 12345 - 41 - RV5C386A 14.8.4. Interrupt Process (1) Periodic Interrupt Set Periodic Interrupt Cycle Selection Bits PRELIMINARY *1) *1) This step is intended to select the level mode as a waveform mode for the periodic interrupt function. *2) This step is intended to set the CTFG bit to 0 in the Control Register 2 to cancel an interrupt to the CPU. Generate Interrupt to CPU CTFG=1? Yes Conduct Periodic Interrupt No Other Interrupt Processes *2) Control Register 2 (X1X1X011) (2) Alarm Interrupt WALE or DALE0 *1) Set Alarm Min., Hr., and Fay-of-week Registers WALE or DALE1 *2) *1) This step is intended to once disable the alarm interrupt circuit by setting the WALE or DALE bits to 0 in anticipation of the coincidental occurrence of a match between current time and preset alarm time in the process of setting the alarm interrupt function. *2) This step is intended to enable the alarm interrupt function after completion of all alarm interrupt settings. *3) This step is intended to once cancel the alarm interrupt function by writing the settings of "X,1,X, 1,X,1,0,1" and "X,1,X,1,X,1,1,0" to the Alarm_W Registers and the Alarm_D Registers, respectively. Generate Interrupt to CPU WAFG or DAFG=1? No Other Interrupt Processes Yes Conduct Alarm Interrupt *3) Control Register 2 (X1X1X101) 12345 - 42 - |
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