M41ST85WMH6E STMicroelectronics, M41ST85WMH6E Datasheet

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Features ■ Automatic battery switchover and WRITE protect for: – Internal serial RTC and – External low power SRAM (LPSRAM) 2 ■ 400 kHz I C serial interface ■ 3.0/3.3 V operating voltage – 2.7 to 3.6 V ...

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Contents Contents 1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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M41ST85W 6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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List of tables List of tables Table 1. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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M41ST85W List of figures Figure 1. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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Description 1 Description The M41ST85W is a combination serial real-time clock, microprocessor supervisor, and NVRAM supervisor built in a low power CMOS SRAM process and has a 64-byte memory space with 44 bytes of NVRAM and 20 memory-mapped ...

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M41ST85W M4T28-BR12SH1 (48 mAh) and M4T32-BR12SH1 (120 mAh). For the extended temperature requirement, the 120 mAh M4T32-BR12SH6 is available. For more information, see Table 19 on page Caution: Do not place the SNAPHAT lithium button-cell battery. The 300 mil SOX ...

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Description Table 1. Signal names E CON EX IRQ/FT/OUT PFI PFO RST RSTIN1 RSTIN2 SCL SDA SQW WDI OUT V SS (1) V BAT For 28-pin, 300 mil embedded crystal SOIC only. Figure 2. ...

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M41ST85W Figure 3. 28-pin, 300 mil SOIC (MX) connections Note: No function (NF) pins should be tied to V shorted together ...

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Description Figure 4. Block diagram SDA INTERFACE SCL (2) 32KHz Crystal OSCILLATOR WDI BAT RSTIN1 RSTIN2 EX PFI 1.25V (Internal) 1. Open drain output. 2. Crystal integrated into SOIC package for MX package option. 10/41 REAL TIME ...

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M41ST85W Figure 5. Hardware hookup Regulator Unregulated V IN Voltage Pushbutton Required for embedded crystal (MX) package only. M41ST85W SCL SDA WDI RSTIN1 RSTIN2 Reset PFI (1) IRQ/FT/OUT V BAT V SS ...

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Operating modes 2 Operating modes The M41ST85W clock operates as a slave device on the serial bus. Access is obtained by implementing a start condition followed by the correct slave address (D0h). The 64 bytes contained in the device can ...

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M41ST85W Accordingly, the following bus conditions have been defined: 2.1.1 Bus not busy Both data and clock lines remain high. 2.1.2 Start data transfer A change in the state of the data line, from high to low, while the clock ...

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Operating modes Figure 6. Serial bus data transfer sequence CLOCK DATA START CONDITION Figure 7. Acknowledgement sequence START SCL FROM MASTER DATA OUTPUT BY TRANSMITTER DATA OUTPUT BY RECEIVER Figure 8. Write cycle timing: RTC & external SRAM control signals ...

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M41ST85W 2.2 Read mode In this mode the master reads the M41ST85W slave after setting the slave address (see Figure 9). 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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Operating modes Figure 10. Read mode sequence BUS ACTIVITY: MASTER SDA LINE S BUS ACTIVITY: SLAVE ADDRESS DATA n+X Figure 11. Alternate read mode sequence BUS ACTIVITY: MASTER SDA LINE S BUS ACTIVITY: SLAVE ADDRESS 16/41 WORD S ADDRESS (An) ...

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M41ST85W 2.3 Write mode In this mode the master transmitter transmits to the M41ST85W slave receiver. Bus protocol is shown in Figure is placed on the bus and indicates to the addressed device that word address An will follow and ...

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Operating modes If data retention lifetime is a critical parameter for the system important to review the data retention current specifications for the particular SRAMs being evaluated. Most SRAMs specify a data retention current at 3.0 volts. Manufacturers ...

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M41ST85W 3 Clock operation The eight byte clock register (see read the date and time from the clock binary coded decimal format. Tenths/hundredths of seconds, seconds, minutes, and hours are contained within the first four registers. Note: A ...

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Clock operation ® Table 2. 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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M41ST85W 3.3 Calibrating the clock The M41ST85W 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 at 25 Calibration circuit is ...

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Clock operation Figure 13. Crystal accuracy across temperature Frequency (ppm –20 –40 –60 –80 –100 –120 –140 –160 –40 –30 –20 Figure 14. Calibration waveform NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION 22/ – T ...

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M41ST85W 3.4 Setting alarm clock registers Address locations 0Ah-0Eh contain the alarm settings. 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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Clock operation Figure 16. Backup mode alarm waveform PFD V SO ABE, AFE Bits in Interrupt Register AF bit in Flags Register IRQ/FT/OUT 3.5 Watchdog timer The watchdog timer can be used to detect an out-of-control microprocessor. ...

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M41ST85W pin. This will also disable the watchdog function until it is again programmed correctly. A READ of the flags register will reset the watchdog flag (bit D7; register 0Fh). The watchdog function is automatically disabled upon power-up and the ...

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Clock operation 3.8 Reset inputs (RSTIN1 & RSTIN2) The M41ST85W provides two independent inputs which can generate an output reset. The duration and function of these resets is identical to a reset generated by a power cycle. Table 5 and ...

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M41ST85W follows PFI. If the comparator is unused, PFI should be connected to V unconnected. 3.10 Century bit Bits D7 and D6 of clock register 03h contain the CENTURY ENABLE bit (CEB) and the CENTURY bit (CB). Setting CEB to ...

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Clock operation 3.13 t bit rec Bit D7 of clock register 04h contains the t continuation of the deselect time after V time before WRITEs may again be performed to the device after a power-down condition. The t bit will ...

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... These are stress ratings only and operation of the device at these or any other conditions above those indicated in the operating sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 8. ...

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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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M41ST85W Table 11. DC characteristics Sym Parameter Battery current OSC ON (2) I BAT Battery current OSC OFF I Supply current CC1 I Supply current (standby) CC2 Input leakage current ( Input leakage current (PFI) (4) I Output ...

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DC and AC parameters Figure 19. Bus timing requirements sequence SDA tBUF SCL P S Table 12. AC characteristics Symbol f SCL clock frequency SCL t Time the bus must be free before a new transmission can start BUF t ...

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M41ST85W Figure 20. Power down/up mode AC waveforms PFD (max) V PFD (min tPD PFO INPUTS RECOGNIZED RST OUTPUTS VALID (PER CONTROL INPUT) E CON Table 13. Power down/up AC characteristics Symbol (2) t ...

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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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M41ST85W Figure 22. SH – 4-pin SNAPHAT Note: Drawing is not to scale. Table 15. SH – 4-pin SNAPHAT Symbol Typ ® housing for 48 mAh battery & crystal, package ...

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Package mechanical data Figure 23. SH – 4-pin SNAPHAT Note: Drawing is not to scale. Table 16. SH – 4-pin SNAPHAT Symbol Typ 36/41 ® housing for 120 mAh battery ...

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M41ST85W Figure 24. SOX28 – 28-lead plastic small outline, 300 mils, embedded crystal, package outline SO-E Note: Drawing is not to scale. Table 17. SOX28 – 28-lead plastic small outline, 300 mils, embedded crystal, mechanical data ...

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Part numbering 7 Part numbering Table 18. Ordering information scheme Example: Device type M41ST Supply voltage and write protect voltage 85W = V = 2.7 to 3.6 V; 2.55V CC Package ( SOH28 ( SOX28 Temperature ...

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M41ST85W 8 Environmental information Figure 25. Recycling symbols This product contains a non-rechargeable lithium (lithium carbon monofluoride chemistry) button cell battery fully encapsulated in the final product. Recycle or dispose of batteries in accordance with the battery manufacturer's instructions and ...

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Revision history 9 Revision history Table 20. Document revision history Date Revision Aug-2000 1 First issue 24-Aug-2000 1.1 Block Diagram added 12-Oct-2000 1.2 t Table removed, cross references corrected rec 18-Dec-2000 2 Reformatted, TOC added, and PFI Input Leakage Current ...

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... M41ST85W 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 any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. ...