M41T81MY6 STMICROELECTRONICS [STMicroelectronics], M41T81MY6 Datasheet
M41T81MY6
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M41T81MY6 Summary of contents
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FEATURES SUMMARY 2.0 TO 5.5V CLOCK OPERATING VOLTAGE COUNTERS FOR TENTHS/HUNDREDTHS OF SECONDS, SECONDS, MINUTES, HOURS, DAY, DATE, MONTH, YEAR, and CENTURY AUTOMATIC SWITCH-OVER and DESELECT CIRCUITRY SERIAL INTERFACE SUPPORTS I (400KHz PROTOCOL) PROGRAMMABLE ALARM and INTERRUPT FUNCTION (valid even ...
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M41T81 TABLE OF CONTENTS SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Figure 19. Back-up Mode Alarm Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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M41T81 SUMMARY DESCRIPTION The M41T81 Serial Access TIMEKEEPER SRAM is a low power Serial RTC with a built-in 32.768 KHz oscillator (external crystal controlled). Eight bytes of the SRAM (see Table 10, page 16) are used for the clock/calendar function ...
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Figure 5. 8-pin SOIC (M) Connections M41T81 BAT Figure 6. 18-pin, 300mil SOIC (MY) Connections ...
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M41T81 MAXIMUM RATING Stressing the device above the rating listed in the “Absolute Maximum Ratings” table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above ...
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DC AND AC PARAMETERS This section summarizes the operating and mea- surement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC Characteristic tables are derived from tests performed under ...
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M41T81 Table 5. DC Characteristics Sym Parameter I Input Leakage Current LI I Output Leakage Current LO I Supply Current CC1 I Supply Current (standby) CC2 V Input Low Voltage IL V Input High Voltage IH Output Low Voltage V ...
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OPERATION The M41T81 clock operates as a slave device on the serial bus. Access is obtained by implementing a start condition followed by the correct slave ad- dress (D0h). The 20 bytes contained in the device can then be accessed ...
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M41T81 Figure 10. Serial Bus Data Transfer Sequence CLOCK DATA START CONDITION Figure 11. Acknowledgement Sequence START SCL FROM MASTER DATA OUTPUT BY TRANSMITTER DATA OUTPUT BY RECEIVER 10/28 DATA LINE STABLE DATA VALID CHANGE OF DATA ALLOWED 1 2 ...
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Figure 12. Bus Timing Requirements Sequence SDA tBUF SCL P Table 7. AC Characteristics Sym f SCL Clock Frequency SCL t Clock Low Period LOW t Clock High Period HIGH t SDA and SCL Rise Time R t SDA and ...
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M41T81 READ Mode In this mode the master reads the M41T81 slave after setting the slave address (see Figure 14, page 12). Following the WRITE Mode Control Bit (R/W=0) and the Acknowledge Bit, the word ad- dress 'An' is written ...
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Figure 15. Alternative READ Mode Sequence BUS ACTIVITY: MASTER SDA LINE S BUS ACTIVITY: ADDRESS WRITE Mode In this mode the master transmitter transmits to the M41T81 slave receiver. Bus protocol is shown in Figure 16, page 13. Following the ...
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M41T81 Data Retention Mode With valid V applied, the M41T81 can be ac- CC cessed as described above with READ or WRITE Cycles. Should the supply voltage decay, the pow- er input will be switched from the V battery when ...
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CLOCK OPERATION The 20-byte Register Map (see Table 10, page 16) is used to both set the clock and to read the date and time from the clock binary coded decimal format. Tenths/Hundredths of Seconds, Seconds, Minutes, and ...
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M41T81 ® Table 10. TIMEKEEPER Register Map Addr D7 D6 00h 0.1 Seconds 01h ST 10 Seconds 02h 0 10 Minutes 03h CEB CB 04h 0 0 05h 0 0 06h 0 0 07h 10 Years 08h OUT FT 09h ...
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Calibrating the Clock The M41T81 is driven by a quartz controlled oscil- lator with a nominal frequency of 32,768 Hz. The devices are tested not exceed –25 to +45 PPM (parts per million) oscillator frequency error ...
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M41T81 Setting Alarm Clock Registers Address locations 0Ah-0Eh contain the alarm set- tings. The alarm can be configured to go off at a prescribed time on a specific month, date, hour, minute, or second or repeat every year, month, day, ...
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Table 11. Alarm Repeat Modes RPT5 RPT4 Watchdog Timer The watchdog timer can be used to detect an out- of-control microprocessor. The user programs the watchdog timer by ...
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M41T81 Square Wave Output The M41T81 offers the user a programmable square wave function which is output on the SQW pin. RS3-RS0 bits located in 13h establish the square wave output frequency. These frequencies are listed in Table 12. Once ...
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Century Bit Bits D7 and D6 of Clock Register 03h contain the CENTURY ENABLE Bit (CEB) and the CENTURY Bit (CB). Setting CEB to a '1' will cause CB to tog- gle, either from a '0' to '1' or from ...
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M41T81 Figure 20. Crystal Accuracy Across Temperature Frequency (ppm –20 –40 –60 –80 –100 –120 –140 –160 –40 –30 –20 Figure 21. Clock Calibration NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION 22/ -0.038 ppm ...
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PACKAGE MECHANICAL INFORMATION Figure 22. SO8 – 8-lead Plastic Small Package Outline Note: Drawing is not to scale. Table 14. SO8 – 8-lead Plastic Small Outline (150 mils body width), Package Mechanical Data Symb ...
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M41T81 Figure 23. SOX18 – 18-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Outline SO-J Note: Drawing is not to scale. Table 15. SOX18 – 18-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Mechanical ...
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Figure 24. SOX28 – 28-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Outline SO-E Note: Drawing is not to scale. Table 16. SOX28 – 28-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Mechanical Symbol ...
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M41T81 PART NUMBERING Table 17. Ordering Information Scheme Example: Device Type M41T Supply Voltage and Write Protect Voltage 2.0 to 5.5V CC Package M = SO8 ( SOX28 ( SOX18 Temperature Range ...
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REVISION HISTORY Table 18. Document Revision History Date Rev. # December 2001 1.0 First Issue 21-Jan-02 1.1 Fix table footnotes (Table 5, 6) 01-May-02 1.2 Modify reflow time and temperature footnote (Table 2) 05-Jun-02 1.3 Modify Data Retention text, Trip ...
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M41T81 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its ...