M4T28-BR12SH ST Microelectronics, M4T28-BR12SH Datasheet
M4T28-BR12SH
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M4T28-BR12SH Summary of contents
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FEATURES SUMMARY 5.0 OR 3.0V OPERATING VOLTAGE SERIAL INTERFACE SUPPORTS I (400 KHz) NVRAM SUPERVISOR FOR EXTERNAL LPSRAM OPTIMIZED FOR MINIMAL INTERCONNECT TO MCU 2.5 TO 5.5V OSCILLATOR OPERATING VOLTAGE AUTOMATIC SWITCH-OVER and DESELECT CIRCUITRY CHOICE OF POWER-FAIL DESELECT VOLTAGES ...
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M41ST85Y, M41ST85W TABLE OF CONTENTS SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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M41ST85Y, M41ST85W SUMMARY DESCRIPTION The M41ST85Y/W Serial TIMEKEEPER troller SRAM is a low power 512-bit, static CMOS SRAM organized as 64 words by 8 bits. A built-in 32.768 kHz oscillator (external crystal controlled) and 8 bytes of the SRAM (see ...
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Figure 3. Logic Diagram V BAT ( SCL SDA EX M41ST85Y M41ST85W RSTIN1 RSTIN2 WDI PFI V SS Note: 1. For 28-pin, 300mil embedded crystal SOIC only. Figure 4. 28-pin SOIC Connections 1 SQW ...
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M41ST85Y, M41ST85W Figure 6. Block Diagram SDA INTERFACE SCL (2) Crystal OSCILLATOR WDI BAT RSTIN1 RSTIN2 EX PFI 1.25V (Internal) Note: 1. Open drain output 2. Integrated into SOIC package for MX package option. 6/33 REAL TIME ...
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Figure 7. Hardware Hookup Regulator Unregulated V IN Voltage Pushbutton R1 R2 Note: 1. Required for embedded crystal (MX) package only. MAXIMUM RATING Stressing the device above the rating listed in the “Absolute Maximum Ratings” table may cause permanent damage ...
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M41ST85Y, M41ST85W 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 ...
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Table 5. DC Characteristics Sym Parameter Battery Current OSC ON (2) I BAT Battery Current OSC OFF I Supply Current CC1 Supply Current I CC2 (Standby) Input Leakage Current ( Input Leakage Current (PFI) Output Leakage (4) I ...
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M41ST85Y, M41ST85W OPERATING MODES The M41ST85Y/W clock operates as a slave de- vice on the serial bus. Access is obtained by im- plementing a start condition followed by the correct slave address (D0h). The 64 bytes con- tained in the ...
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Data Valid. The state of the data line represents valid data when after a start condition, the data line is stable for the duration of the high period of the clock signal. The data on the line may be changed ...
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M41ST85Y, M41ST85W Figure 11. WRITE Cycle Timing: RTC & External SRAM Control Signals EX E CON Figure 12. Bus Timing Requirements Sequence SDA tBUF SCL P S Table 6. AC Characteristics Symbol f SCL Clock Frequency SCL t Time the ...
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READ Mode In this mode the master reads the M41ST85Y/W slave after setting the slave address (see Figure 13, page 13). Following the WRITE Mode Control Bit (R/W=0) and the Acknowledge Bit, the word address 'An' is written to the ...
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M41ST85Y, M41ST85W Figure 15. Alternate READ Mode Sequence BUS ACTIVITY: MASTER SDA LINE S BUS ACTIVITY: ADDRESS WRITE Mode In this mode the master transmitter transmits to the M41ST85Y/W slave receiver. Bus protocol is shown in Figure 16, page 14. ...
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Data Retention Mode With valid V applied, the M41ST85Y/W can be CC accessed as described above with READ or WRITE Cycles. Should the supply voltage decay, the M41ST85Y/W will automatically deselect, write protecting itself (and any external SRAM) when V ...
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M41ST85Y, M41ST85W Figure 17. Power Down/Up Mode AC Waveforms PFD (max) V PFD (min tPD PFO INPUTS RECOGNIZED RST OUTPUTS VALID (PER CONTROL INPUT) E CON Table 7. Power Down/Up AC Characteristics Symbol (2) V ...
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CLOCK OPERATION The eight byte clock register (see Table 8, page 18) 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, ...
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M41ST85Y, M41ST85W ® Table 8. TIMEKEEPER Register Map Address D7 D6 00h 0.1 Seconds 01h ST 10 Seconds 02h 0 10 Minutes 03h CEB CB 04h TR 0 05h 0 0 06h 0 0 07h 10 Years 08h OUT FT ...
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Calibrating the Clock The M41ST85Y/W is driven by a quartz controlled oscillator with a nominal frequency of 32,768 Hz. The devices are tested not exceed +/–35 PPM (parts per million) oscillator frequency error which equates to ...
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M41ST85Y, M41ST85W The IRQ/FT/OUT output is cleared by a READ to the Flags Register. A subsequent READ of the Flags Register is necessary to see that the value of the Alarm Flag has been reset to '0.' The IRQ/FT/OUT pin ...
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Figure 19. Back-Up Mode Alarm Waveform PFD V SO ABE, AFE Bits in Interrupt Register AF bit in Flags Register IRQ/FT/OUT Watchdog Timer The watchdog timer can be used to detect an out- of-control microprocessor. The user ...
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M41ST85Y, M41ST85W Square Wave Output The M41ST85Y/W offers the user a programma- ble square wave function which is output on the SQW pin. RS3-RS0 bits located in 13h establish the square wave output frequency. These fre- quencies are listed in ...
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Power-on Reset The M41ST85Y/W continuously monitors V When V falls to the power fail detect trip point, CC the RST pulls low (open drain) and remains low on power-up for t after V REC CC The RST pin is an ...
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M41ST85Y, M41ST85W Power-fail INPUT/OUTPUT The Power-Fail Input (PFI) is compared to an in- ternal reference voltage (1.25V). If PFI is less than the power-fail threshold (V PFI Output (PFO) will go low. This function is intended for use as an ...
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Table 12. t Definitions REC t Bit (TR) STOP Bit (ST) REC Note: 1. Default Setting Table 13. Default Values Condition (2) Initial Power-up Subsequent Power-up (with (3) battery back-up) Note: 1. WDS, BMB0-BMB4, RB0, RB1. 2. ...
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M41ST85Y, M41ST85W Figure 21. Crystal Accuracy Across Temperature Frequency (ppm –20 –40 –60 –80 –100 –120 –140 –160 –40 –30 –20 Figure 22. Calibration Waveform NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION 26/ -0.038 ppm ...
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... For a list of available options (e.g., Speed, Package) or for further information on any aspect of this device, please contact the ST Sales Office nearest to you. Table 15. SNAPHAT Battery Table Part Number M4T28-BR12SH Lithium Battery (48mAh) and Crystal SNAPHAT M4T32-BR12SH Lithium Battery (120mAh) and Crystal SNAPHAT M41ST V 4 ...
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M41ST85Y, M41ST85W PACKAGE MECHANICAL INFORMATION Figure 23. SOH28 – 28-lead Plastic Small Outline, Battery SNAPHAT, Package Outline SOH-A Note: Drawing is not to scale. Table 16. SOH28 – 28-lead Plastic Small Outline, battery SNAPHAT, Package ...
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Figure 24. SH – 4-pin SNAPHAT Housing for 48mAh Battery & Crystal, Package Outline Note: Drawing is not to scale. Table 17. SH – 4-pin SNAPHAT Housing for 48mAh Battery & Crystal, Package Mechanical Data Symbol Typ ...
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M41ST85Y, M41ST85W Figure 25. SH – 4-pin SNAPHAT Housing for 120mAh Battery & Crystal, Package Outline Note: Drawing is not to scale. Table 18. SH – 4-pin SNAPHAT Housing for 120mAh Battery & Crystal, Package Mechanical Data Symbol Typ A ...
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Figure 26. SOX28 – 28-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Outline SO-E Note: Drawing is not to scale. Table 19. SOX28 – 28-lead Plastic Small Outline, 300mils, Embedded Crystal, Package Mechanical Symbol ...
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M41ST85Y, M41ST85W REVISION HISTORY Table 20. Document Revision History Date Rev. # August 2000 1.0 First issue 24-Aug-00 1.1 Block Diagram added (Figure 3) 12-Oct-00 1.2 t Table removed, cross references corrected REC 18-Dec-00 2.0 Reformatted, TOC added, and PFI ...
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M41ST85, M41ST85Y, M41ST85W, 41ST85, ST85, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVI- SOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, SUPERVISOR, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, Serial, ...