M41T93_11 STMICROELECTRONICS [STMicroelectronics], M41T93_11 Datasheet
M41T93_11
Related parts for M41T93_11
M41T93_11 Summary of contents
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Serial SPI bus real-time clock with battery switchover Features ■ Ultra-low battery supply current of 365 nA ■ Factory calibrated accuracy guaranteed after 2 reflows (SOX18) – Much better accuracies achievable using built-in programmable analog and digital calibration circuits ■ ...
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Contents Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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M41T93 3.10 Battery low warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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List of tables List of tables Table 1. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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M41T93 List of figures Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Description 1 Description The M41T93 is a low-power serial SPI bus real-time clock with a built-in 32.768 kHz oscillator (external crystal-controlled for the QFN16 package, and embedded crystal for the SOX18 package). Eight bytes of the register map are used ...
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M41T93 Figure 1. Logic diagram 1. For QFN16 package only 2. Defaults to 32 KHz on power-up 3. Open drain Table 1. Signal names Symbol (1) XI (1) XO IRQ/FT/OUT (2) SQW RST E SDI SDO SCL V BAT (3) ...
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Description Figure 2. QFN16 connections 1. Open drain output 2. Defaults to 32 KHz on power-up Figure 3. SOX18 connections 1. NF pins must be tied Open drain output 3. Do not use (must be tied to ...
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M41T93 Figure 4. Block diagram CRYSTAL E SDI SCL SDO BAT V RST /V SO (2) 1. Open drain output 2.93 V (S), 2.63 V (R), and 2.32 V (Z) RST SO ...
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Description Figure 5. Hardware hookup V CC M41T93 V CC IRQ/FT/OUT BAT Open drain output 2. CPOL (clock polarity) and CPHA (clock phase) are bits that may be set in the SPI control register ...
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M41T93 1.1 SPI signal description 1.1.1 Serial data output (SDO) The output pin is used to transfer data serially out of the memory. Data is shifted out on the falling edge of the serial clock. 1.1.2 Serial data input (SDI) ...
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Operation 2 Operation The M41T93 clock operates as a slave device on the SPI serial bus. Each memory device is accessed by a simple serial interface that is SPI bus-compatible. The bus signals are SCL, SDI, and SDO (see when ...
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M41T93 2.1 SPI bus characteristics The serial peripheral interface (SPI) bus is intended for synchronous communication between different ICs. It consists of four signal lines: serial data input (SDI), serial data output (SDO), serial clock (SCL) and a chip enable ...
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Operation Figure 7. READ mode sequence SCL 7 BIT ADDRESS W/R BIT SDI MSB SDO HIGH IMPEDANCE Figure 8. WRITE mode sequence SCL 7 BIT ADDR ...
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M41T93 2.3 Data retention and battery switchover (V Once V falls below the switchover voltage (V CC switches over to the battery and powers down into an ultra low current mode of operation to preserve battery life from ...
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Clock operation 3 Clock operation The M41T93 is driven by a quartz-controlled oscillator with a nominal frequency of 32.768 kHz. The accuracy of the real-time clock depends on the frequency of the quartz crystal that is used as the time-base ...
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M41T93 3.1 Clock data coherency In order to synchronize the data during reads and writes of the real-time clock device, a set of buffer transfer registers resides between the SPI serial interface on the user side, and the clock/calendar counters ...
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Clock operation 3.1.2 Accessing the device The M41T93 is comprised of 32 addresses which provide access to registers for time and date, digital and analog calibration, two alarms, watchdog, flags, timer, squarewave and NVRAM. The clock and alarm parameters are ...
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M41T93 3.2.1 Power-down time stamp Some applications may need to determine the amount of time spent in backup mode. That can be calculated if the time of power-down and the time of power-up are known. The latter is straightforward to ...
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Clock operation Table 3. Clock/control register map (32 bytes) Addr 00h 0.1 seconds 01h ST 10 seconds 02h 0 10 minutes 03h CB1 CB0 10 hours 04h 05h 0 0 06h ...
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M41T93 3.3 Real-time clock accuracy The M41T93 is driven by a quartz controlled oscillator with a nominal frequency of 32,768 Hz. The accuracy of the real-time clock is dependent upon the accuracy of the crystal, and the match between the ...
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Clock operation 3.4 Clock calibration The M41T93 oscillator is designed for use with a 12.5 pF crystal load capacitance. When the calibration circuit is properly employed, accuracy improves to better than ±1 ppm at 25 °C. The M41T93 design provides ...
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M41T93 Table 4. Digital calibration values Calibration value (binary) DC4 – DC0 0 (00000) 1 (00001) 2 (00010) 3 (00011) 4 (00100) 5 (00101) 6 (00110) 7 (00111) 8 (01000) 9 (01001) 10 (01010) 11 (01011) 12 (01100) 13 (01101) ...
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Clock operation 3.4.2 Analog calibration (programmable load capacitance) A second method of calibration employs the use of programmable internal load capacitors to adjust (or trim) the oscillator frequency. By design, the oscillator is intended ppm ± crystal ...
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M41T93 Figure 11. Crystal accuracy across temperature Frequency (ppm –20 –40 –60 –80 –100 –120 –140 –160 –40 –30 –20 Table 5. Analog calibration values D7 D6 Analog Addr calibration ACS AC6 value (16 pF) (± ...
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Clock operation The on-chip capacitance can be calculated as follows: For example: C (12h = x0000000) = 12.5 pF LOAD C (12h =11001000) = 3.5 pF and LOAD C (12h = 00100111) = 17.4 pF LOAD The oscillator sees a ...
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M41T93 Two methods are available for ascertaining how much calibration a given M41T93 may require: ● The first involves setting the clock, letting it run for a month and comparing known accurate reference and recording deviation over ...
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Clock operation Figure 14. Crystal isolation example Note: The substrate pad should be tied to V 3.5 Setting the alarm clock registers Address locations 0Ah-0Eh (alarm 1) and 14h-18h (alarm 2) contain the alarm settings. Either alarm can be configured ...
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M41T93 3.6 Optional second programmable alarm When the alarm 2 enable (AL2E) bit (D1 of address 13h) is set to a logic ‘1,’ registers 14h through 18h provide control for a second programmable alarm which operates in the same manner ...
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Clock operation 3.7 Watchdog timer The watchdog timer can be used to detect an out-of-control microprocessor. The user programs the watchdog timer by setting the desired amount of time-out into the watchdog register, address 09h. Bits BMB4-BMB0 store a binary ...
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M41T93 3.8.1 TI/TP ● TI/ IRQ/FT/OUT is active when TF is logic '1' (subject to the status of the timer interrupt enable bit (TIE). ● TI/ IRQ/FT/OUT pulses active according to Note alarm condition, ...
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Clock operation 3.8.5 TD1/0 These are the timer source clock frequency selection bits (see determine the source clock for the countdown timer (see TD1 and TD0 bits should be set to ‘11’ (1/60 Hz) for power saving. Table 9. Timer ...
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M41T93 3.9 Square wave output The M41T93 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 completed, the ...
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Clock operation 3.10 Battery low warning The M41T93 automatically performs battery voltage monitoring upon power-up and at factory-programmed time intervals of approximately 24 hours. The battery low (BL) bit, bit D4 of flags register 0Fh, will be asserted if the ...
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M41T93 3.13 Oscillator fail detection If the oscillator fail (OF) bit is internally set to a '1,' this indicates that the oscillator has either stopped, or was stopped for some period of time and can be used to judge the ...
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Clock operation 3.15 Initial power-on defaults Upon initial application of power to the device, the register bits will initially power-on in the state indicated in Table 13. Initial power-on default values (part 1) (1) Condition ST CB1 CB0 OUT FT ...
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M41T93 4 Maximum ratings 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 ...
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DC and AC parameters 5 DC and AC parameters This section summarizes the operating and measurement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC characteristic tables are derived ...
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M41T93 Table 18. DC characteristics Sym Parameter Operating voltage (S) V Operating voltage (R) CC Operating voltage (Z) I Input leakage current LI I Output leakage current LO Supply current I SCL = 0.1V /0.9V CC1 CC CC SDO = ...
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DC and AC parameters Figure 18. I CC2 10.000 9.000 8.000 7.000 6.000 5.000 4.000 3.000 2.000 -40 Table 19. Crystal electrical characteristics Symbol f Resonant frequency O R Series resistance S C Load capacitance L 1. Externally supplied if ...
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M41T93 Figure 19. Power down/up mode AC waveforms tPD SCL SDI Table 21. Power down/up trip points DC characteristics Sym V Reset threshold voltage RST Battery backup switchover V SO Hysteresis Reset pulse width (V t ...
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DC and AC parameters Figure 20. Input timing requirements E tCHEL SCL tDVCH MSB IN SDI HIGH IMPEDANCE SDO Figure 21. Output timing requirements E SCL tCLQV tCLQX MSB OUT SDO ADDR. LSB IN SDI 42/51 tELCH tCHEH tCHDX tCLCH ...
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M41T93 Table 22. AC characteristics Sym f SCL clock frequency SCL t E active setup time ELCH t E not active setup time EHCH t E deselect time EHEL t E active hold time CHEH t E not active hold ...
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Package mechanical data 6 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available ...
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M41T93 Figure 22. QFN16 – 16-lead, quad, flat package, no lead body size, outline 1. Drawing is not to scale 2. Substrate pad should be tied to V Table 23. QFN16 – 16-lead, quad, flat package, ...
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Package mechanical data Figure 23. QFN16 – 16-lead, quad, flat, no lead mm, recommended footprint 1. Dimensions shown are in millimeters (mm) 2. Substrate pad should be tied to V Figure 24. 32 KHz crystal + QFN16 ...
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M41T93 Figure 25. SOX18 – 18-lead plastic small outline, 300 mils, embedded crystal Note: Drawing is not to scale. Table 24. SOX18 – 18-lead plastic SO, 300 mils, embedded crystal, pkg. mech. data Sym A A1 ...
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Part numbering 7 Part numbering Table 25. Ordering information Example: Device family M41T Device type 93 Operating voltage 3. 2. ...
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M41T93 8 References Below is a listing of the crystal component suppliers mentioned in this document. ● KDS can be contacted at kouhou@kdsj.co.jp or http://www.kdsj.co.jp. ● Citizen can be contacted at csd@citizen-america.com or http://www.citizencrystal.com. ● Micro Crystal can be contacted ...
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Revision history 9 Revision history Table 26. Document revision history Date Revision 07-Aug-2006 08-May-2007 22-Oct-2007 15-Aug-2008 19-Oct-2010 12-Oct-2011 50/51 1 Initial release. Document status upgraded to full datasheet; updated accuracy vs. on-chip load capacitors; 2 Table 1, 15, and 18, ...
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M41T93 Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at ...