M41T93

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Serial SPI bus real-time clock (RTC) with battery switchover

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Product overview

Description

The M41T93 is a low-power serial SPI bus real-time clock (RTC) 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 for the clock/calendar function and are configured in binary coded decimal (BCD) format. An additional 17 bytes of the register map provide status/control of the two alarms, watchdog, 8-bit counter, and square wave functions. An additional seven bytes are made available as user SRAM.

Addresses and data are transferred serially via a serial SPI bus-compatible interface. The built-in address register is incremented automatically after each WRITE or READ data byte. The M41T93 has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the clock operations can be supplied by a small lithium button battery when a power failure occurs.

Functions available to the user include a non-volatile, time-of-day clock/calendar, alarm interrupt, watchdog timer, programmable 8-bit counter, and square wave outputs. The eight clock address locations contain the century, year, month, date, day, hour, minute, second, and tenths/hundredths of a second in 24-hour BCD format. Corrections for 28, 29 (leap year), 30, and 31 day months are made automatically. The M41T93 is supplied in either a QFN16 or an SOX18, 300 mil SOIC which includes an embedded 32 KHz crystal. The SOX18 package requires only a user-supplied battery to provide non-volatile operation.

  • All features

    • Ultra-low battery supply current of 365 nA
    • Factory calibrated accuracy ±5 ppm typical after 2 reflows (SOX18) (much better accuracies are achievable using built-in programmable analog and digital calibration circuits)
    • 2.0 V to 5.5 V clock operating voltage
    • Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century
    • Automatic switchover and reset output circuitry (fixed reference): M41T93S: VCC= 3.0 V to 5.5 V; M41T93R: VCC= 2.7 V to 5.5 V; M41T93Z: VCC= 2.38 V to 5.50 V
    • Compatible with SPI bus serial interface (supports SPI mode 0 [CPOL = 0, CPHA = 0])
    • Programmable alarm with interrupt function (valid even during battery backup mode)
    • Optional 2ndprogrammable alarm available
    • Square wave output (defaults to 32 KHz on power-up)
    • RESET (RST) output
    • Watchdog timer
    • Programmable 8-bit counter/timer
    • 7 bytes of battery-backed user SRAM
    • Battery low flag
    • Low operating current of 80 μA
    • Oscillator stop detection
    • Battery or supercapacitor backup
    • Operating temperature of –40 °C to +85 °C
    • Package options include a 16-lead QFN and an 18-lead embedded crystal SOIC

Circuit Diagram

The current status of a product:
Active: Product is in volume production
Evaluation: Product is under characterization. Limited Engineering samples available
Preview: Product is in design stage
Target: Product is in design feasibility stage.No commitment taken to produce
Proposal: Marketing proposal for customer feedback.No commitment taken to design or produce
NRND: Not Recommended for New Design.Product is in volume production only to support customers ongoing production.
Marketing description of the package type.Compliancy of the device with industry requirement domains (IRD)The RoHS status of a product:
ECOPACK 1: Initial grade to identify European RoHS compliant products.
ECOPACK 2: New grade to identify brominated chlorinated and antimony oxide flame retardant free products.
ECOPACK 3: Halogen free RoHS exemptions free products.
(*): ECOPACK 2 version available upon request.
(**): Some versions still existing in ECOPACK 1 or not compliant.
The current status of a product:
Active: Product is in volume production
Evaluation: Product is under characterization. Limited Engineering samples available
Preview: Product is in design stage
Target: Product is in design feasibility stage.No commitment taken to produce
Proposal: Marketing proposal for customer feedback.No commitment taken to design or produce
NRND: Not Recommended for New Design.Product is in volume production only to support customers ongoing production.
Budgetary PriceMarketing description of the package type.Storage method used to contain product.Main country of assembly or fabrication of the product.ECCNs are five character alpha-numeric designations used on the Commerce Control List to identify dual-use items for export control purposes. ECCNs are five character alpha-numeric designations used on the Commerce Control List to identify dual-use items for export control purposes.The value as specified by level (minTypMax) of the ambient temperature (in Cel) in which this item was designed to operate.The value as specified by level (minTypMax) of the ambient temperature (in Cel) in which this item was designed to operate.The value as specified by level (minTypMax) of the ambient temperature (in Cel) in which this item was designed to operate.