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Serial real-time clock (RTC) ICs

Content

Real-time clock (RTC) ICs spectrum ................................... 3

Low-power real-time clocks for portable devices ........... 4World’s smallest RTC with embedded crystal .................................. 5

Enhanced industry-standard real-time clocks ............... 6Highly accurate, automatic temperature-compensated real-time clock solution with embedded crystal ............................. 6Real-time clocks with analog calibration ........................................ 8

Highly-integrated real-time clocks ................................... 10Combined RTC and microprocessor supervisor ........................... 10Securitizor ..................................................................................... 12

Design support ........................................................................ 16

Widest portfolio of real-time clocks offers unlimited designs solutions

An extended variety of products with the newest technology innovations are available including ultra-low-power devices, the world’s smallest package with embedded crystal, ST’s SNAPHAT® with battery and crystal integrated. RTC functions include alarm, battery switchover, reset, and special features with time stamp, anti-tamper for secure applications, audio, and trickle charge, and an highly-accurate temperature-compensated RTC with embedded crystal.

RTC ICs spectrum

3

Integration

• Low standby current

• World’s smallest RTC with crystal

• Small packages

Low-power for portable devices

• Automatic battery switchover

• Analog calibration

• Embedded crystal

• Temperature-compensated RTC

Enhanced industry-standard

• RTC with NVRAM and microprocessor supervisor functions

• Battery monitor

• Power-on reset/low-voltage detect

Highly-integrated

• Physical tamper detect

• Internal and external RAM clear

• Tamper event timestamp

Securitizor

M41T6x series M41T81S, M41T00S, M41T82/83/93, M41T00CAP, M41TC8025

M41ST85W, M41T94, M41T00AUD

M41ST87W

4

Low-power RTC ICs

Very low standby current extends battery backup life

Special low-power RTC series available in small packages, from 350 nA, with battery switchover, and with or without an embedded crystal to best fit battery-operated device constraints.

Low-powEr rTCs for porTabLE dEviCES porTfoLio

M41T6x• 10ths and 100ths of seconds

• 350 nA standby (typ) at 3.0 V

• 1.3 to 4.4 V operation • 4.4 V max VCC suitable for lithium-ion battery operation

• Timekeeping down to 1.0 V

• 400 kHz I2C Interface

• Programmable watchdog output • 62.5 ms to 31 min • Dedicated output

appLiCaTion ExaMpLES • Digital cameras

• Portable media players

• Medical instruments

• Point-of-sale terminals

• Test equipment

• Portable navigation

• BCD registers for year, month, day, date, hours, minutes and seconds

• 2 century bits (Y2.1 K compliant)

• Automatic leap year adjustment

• Calibration register

• Oscillator fail detect

3 mm

3 mm

0.90 mm

M41T6x

QFN16

part number

package

battery supply current (ibat)

data bus type

400 kHz

Supply voltage

Timekeepingoscillator fail detect

programmable alarms

watchdog timer

Square wave

dedicated ouput

power-up output

frequency (kHz)

Embedded crystal

typ (na)min - max

(v)min (v)

M41T60 QFN16 350 I2C 1.3 - 4.4 1 •1 - - - -

M41T62QFN16 350 I2C 1.3 - 4.4 1 •1 •1 •1 • 32

LCC8 350 I2C 1.3 - 4.4 1 •1 •1 •1 • 32 •

M41T63 QFN16 350 I2C 1.3 - 4.4 1 • - • • 32

M41T64 QFN16 350 I2C 1.3 - 4.4 1 • - • • 32

M41T65 QFN16 350 I2C 1.3 - 4.4 1 •1 •1 • - -

M41T66 QFN16 525 I2C 1.5 - 4.4 1 •1 •1 •1 • 32

Note: 1: With IRQ output

5

worLd’S SMaLLEST rTC wiTH EMbEddEd CrySTaL

M41T62LC6f • RTC in LCC8 package with

embedded crystal

• 10ths and 100ths of seconds

• Programmable alarm with repeat modes and interrupt function

• Programmable watchdog timer • 62.5 ms to 31 min

• Programmable square-wave output • 1 Hz to 32 KHz • 32 KHz and on at power-up (can be disabled)

LCC8

1.5 mm 3.2 mm

Oscillatorfail detect

Out

Square waveCalibration

OFIE

Seconds0.1 Seconds0.01 SecondsCentury bits

AlarmWatchdog

MinutesHoursDateDay

MonthYear

400 kHzI²C

interface

VCC

Microcontroller I²C

I²C

XI

VCC

XO

2

M41T62

IRQ/OUT(Open drain)

SQW

32 KHzoscillator

HigHLy aCCuraTE, auToMaTiC TEMpEraTurE-CoMpEnSaTEd rEaL-TiME CLoCkSoLuTion wiTH EMbEddEd CrySTaLMore applications now require very accurate timekeeping across a wide range of temperature. Multi-rate smart power metering is a typical example,since power companies need to log multi-rate electricity usage for accurate billing. Applications: Smart metering and industrial.

6

Enhanced industry-standard

Class-leading RTCs for smart utility meters and precision applications

Enhanced industry-standard RTC with fixed reference added for highly-reliable battery switchover threshold, plus analog calibration, embedded crystal and oscillator fail detect.

M41TC8025 • Embedded high-stability 32 KHz DTCXO

• Temperature-compensated serial real-time clock • ±5.0 ppm max from -40 to 85 °C • ±3.8 ppm max from 0 to 50 °C

• Supply voltage • Clock operating & timekeeping: 1.6 to 5.5 V • I2C interface operating: 1.8 to 5.5 V • Temperature compensation: 2.2 to 5.5 V

• 0.8 μA typical current at 3.0 V supply voltage

• 400 kHz I2C interface

• Time-of-day alarm (with interrupt)

• Fixed-cycle timer interrupt function

• Time update interrupt function

• Programmable frequency output • F

OUT = 1 Hz, 1 KHz and 32 KHz

• Registers for seconds, minutes, hours, day-of week, date (day of month), month and year with automatic leap year compensation

• Programmable temperature compensation intervals (0.5 s, 2 s default, 10 s, 30 s)

SO14

32 KHztemp-compensated

OSC & capacitor array

Tempsensor

Interruptcontrol

UIE TIE AIETime update

Fixed-cycle timer

Alarm compare

Clock registers

Alarm registers

Non-clock registers

Compensationcontrol

Counter 0 - 99

Counter 1 - 12

Counter 1 - 7Counter 1 - 31

Counter 0 - 23

Counter 0 - 59

Divide by32768

Counter 0 - 59

1 Hz

32 KHz

32 KHz

1 KHz

1 HzSecondsMinutesHours

DateDay-of-week

MonthYear

VCCFOUTSQW

FOE

VSS

SDASCL

I²Cinterface

Time counter 0

Extension regTime counter 1

Flag registerControl reg

Hour alarmMin alarm

Day/week alarmDate alarm

M41TC8025

IRQ

7

M41T00S• Precision reference for battery

switchover threshold

• Oscillator fail detect circuit


• Automatic battery switchover and write-protect

• Calibration register - accuracy to 5 seconds per month

• BCD registers: century, year, month, day, date, hours, minutes, seconds

• 2.7 to 5.5 V operation


• SO8 package

M41T81S • Precision reference for battery

switchover threshold

• Programmable alarm with repeat modes

• Oscillator fail detect circuit

• Battery monitor

• Automatic battery switchover and write-protect

• Calibration register - accuracy to 5 seconds per month

• BCD registers: century, year, month, day, date, hours, minutes, seconds


• Programmable watchdog • 62.5 ms to 128 s time-out

• Programmable square-wave • 1 Hz to 32 KHz


M41T00Cap• Integrated backup battery and

embedded crystal

• Based on M41T00S RTC

• CAPHAT™ PCDIP24 package

• 0 to 70 °C operation

• Up to 10 years of timekeeping without system power

M41T00aud• RTC with integrated audio amplifier


• DFN16 (5 x 4 mm) package

• 0 to 70 °C operation

• 400 nA backup current

• 3.0 to 3.6 V operation

• Automatic battery switchover

• Oscillator fail detect

• Trickle charge circuit for backup capacitor

• Timekeeping down to 1.7 V

audio fEaTurES• 300 mW differential audio amplifier

• 256 and 512 Hz tone generation

• Gain adjustment from - 33 to +12 dB in 3 dB steps

• Automatic shut off in backup mode

PCDIP24 CAPHAT™Embedded crystal + battery (internal view)

XI

XO


SecondsCentury bitsCalibration

Out

MinutesHoursDateDay

MonthYear

VCC

Microcontroller

VCC

400 KHzI²C

interfaceI²C

I²C2

M41T00S

32 KHzoscillator

ReferenceVPFD = 2.6 V

FT/OUT/OSC-FAIL-IRQ

Automaticbattery

switchoverand writeprotect

SO8

XI

XO


SecondsCentury bitsCalibration

0.1 Seconds0.01 Seconds

AlarmWatchdog

Square wave

Out

MinutesHoursDateDay

MonthYear

VCC

Microcontroller

VCC

400 KHzI²C

interfaceI²C

I²C2

M41T81S

ReferenceVPFD = 2.6 V

Batterymonitor

Automaticbattery

switchoverand writeprotect

FREQ-TEST/ALARM/W-DOG/SQ-WAVE/OSC-FAIL-IRQ/OUT

32 KHzoscillator

SOX18 Embedded crystal

(Internal view)

8

rEaL-TiME CLoCkS wiTH anaLog CaLibraTion M41T83, M41T93 • Dual calibration features • Analog calibration • 5 ppm typical at 25 °C after two reflows • Real-time feedback • Pre-programmed in OTP byte (only in SOX18) • Digital calibration


• Automatic battery switchover and write-protect • Precision reference

• 400 kHz I2C, 10 MHz SPI

• 12 bytes of NVRAM • 5 bytes shared with 2 alarm registers

• 2 programmable alarms with repeat modes

• Memory-mapped BCD year, month, day, date, hours, minutes, seconds, 10ths, 100ths of seconds

• 2.38 to 5.5 V operation • Timekeeping down to 1.8 V • Three V

PFD (V

RST) options:

• 2.93 VPFD

@ 3.0 to 5.5 VCC

• 2.63 V

PFD @ 2.7 to 5.5 V

CC

• 2.32 VPFD

@ 2.38 to 5.5 VCC

• Programmable watchdog (62.5 ms to 128 s)

• Programmable squarewave output • 1 Hz to 32 KHz • 32 KHz on at power-up (can be disabled)

M41T82 • Light version of M41T83, pin-to-pin

compatible with earlier RTCs in SO8 packages

• Dual calibration features • Analog calibration - real-time feedback • Digital calibration

• Automatic battery switchover and write-protect • Precision reference

• 400 kHz I2C


• 12 bytes of NVRAM

• 2.38 to 5.5 V operation • Timekeeping down to 1.8 V • Three VPFD (VRST) options: • 2.93 V

PFD @ 3.0 to 5.5 V

CC

• 2.63 VPFD

@ 2.7 to 5.5 VCC

• 2.32 V

PFD @ 2.38 to 5.5 V

CC

• Memory-mapped BCD year, month, day, date, hours, minutes, seconds • 10ths, 100ths of seconds

MonthYear

Seconds2 Century bits0.1 Seconds0.01 SecondsA. cal (REG)A. cal (OTP)


Auto-reload8-bit tmr/cntr

Alarm1D. cal

Alarm2Watchdog

Out

NVRAM12 bytes

Square ware

MinutesHoursDateDay

VCC VBAT

Microcontroller

VCC

400 KHz I²C T83SPI: T93I²C/

SPI

I²C/SPI

2/4

M41T83, M41T93

Automatic batteryswitchover andwrite protect

ReferenceVPFD (VRST) = 2.6 V

Batterymonitor

IRQ/FT/OUT(W-DOG/ALARM-IRQ/FT/OUT/OSC-FAIL-IRQ/TIMER-IRQ)

IRQ2

SQW(Defaultsto 32 KHzand on; canbe disabled)

OTP onlyon SOX18package

POR/LVD

(SOX18only)

VPP

32 KHzoscillator

SOX18Embedded crystal

(internal view)4 mm

4 mm

0.90 mm QFN16

M41T83

MonthYear

Seconds2 Century bits0.1 Seconds0.01 Seconds

Analog cal


Auto-reload8-bit tmr/cntr

Digital cal

NVRAM12 bytes

MinutesHoursDateDay

VCC VBAT

Microcontroller

XI

XO

VCC M41T82

Automatic batteryswitchover andwrite protect

ReferenceVPFD (VRST) = 2.6 V

Batterymonitor

POR/LVD

400 KHz I²CI²C

I²C

2

32 KHzoscillator

SO8

9

appLiCaTion ExaMpLES • Home multimedia

• Metering (gas, electricity, water)

• Multi-function printers

• Vehicle tracking systems

part number

pack

age

battery supply current (ibat)

nvraMsize data

bus type

vCC

Tim

ekee

ping

min

(v)

b atte

rysw

itcho

ver

osci

llato

r fai

l de

tect

prog

ram

mab

leal

arm

s

Squa

re w

ave

outp

ut

pow

er-u

p ou

tput

fr

eque

ncy

(kHz

)

wat

chdo

gtim

er

batte

ry lo

w

dete

ct

pow

er o

nre

set/

low

volta

ge d

etec

tor

outp

ut

Embe

dded

cry

stal

Tem

pera

ture

co

mpe

nsat

ed

typ (na) (bytes)min -

max (v)

M41T0 SO-8 900 - I²C2 2 - 5.5 2 - • - - - - - - - -

M41T00S SO-8 600 - I²C2 2.7 - 5.5 2 •5 • - - - - - - - -

M41T00aud DFN16 600 - I²C2 3 - 3.6 1.7 •5 •3 - - - - - - - -

M41T00Cap PCDIP241 - - I²C2 2.7 - 5.5 - •5 • - - - - - - • -

M41T11SO-8 800 56 I²C 2 - 5.5 2 • - - - - - - - - -

SOH-28 800 56 I²C 2 - 5.5 2 • - - - - - - - - -

M41T56 SO-8 450 56 I²C 4.5 - 5.5 2.5 • - - - - - - - - -

M41T80 SO-8 1500 - I²C2 2 - 5.5 2 - - •3 •3 324 - - - - -

M41T81SSO-8 600 - I²C2 2.7 - 5.5 2 •5 •3 •3 •3 - •3 • - - -

SOX-18 600 - I²C2 2.7 - 5.5 2 •5 •3 •3 •3 - •3 • - • -

M41T82 SO-8 365 12 I²C2 2.38 - 5.5 1.8 •5 • - - - - • • • -

M41T83QFN16 365 12 I²C2 2.38 - 5.5 1.8 •5 •3 •3 •4 32 •3 • • • -

SOX-18 365 12 I²C2 2.38 - 5.5 1.8 •5 •3 •3 •4 32 •3 • • •

M41T93QFN16 365 12 SPI6 2.38 - 5.5 1.8 •5 •3 •3 •4 32 •3 • • • -

SOX-18 365 12 SPI6 2.38 - 5.5 1.8 •5 •3 •3 •4 32 •3 • • •

M41TC8025 S0-14 800 - I²C 1.6 - 5.5 1.6 - - • • 32 - • • • •

Note:1: Integrated battery and embedded crystal2: 400 kHz3: With IRQ output4: Dedicated output5: Fixed switchover reference6: 10 MHz

EnHanCEd induSTry-STandard rTCs porTfoLio

Long-LifE baTTEry baCkup

48 mah baTTEry 12 yEarS baCkup LifE M41T56 baTTEry baCkup• Backup life t = battery capacity / battery current

• BR1225 capacity = 48 mAh

• M41T56 backup current IBAT = 450 nA (typical)

• Backup life t = BR1225 capacity / IBAT

t = 48 mAh / 450 nA = 106,666.7 hours = 4444.4 days

• Backup life t = 12.2 years

M41T56

VCC

VCC = 5 V

VBATVBAT

BR1225Li coin cell VSS

10

Highly-integrated RTC

Combined RTC and Microprocessor supervisor

Highly-integrated RTCs with NVRAM and a large set of microprocessor supervisory functions, including battery monitor, power-on reset and low-voltage detect.

M41T94 • Automatic battery switchover

• Power-fail detect and write-protect

• 2 MHz SPI bus

• THS pin selects 5 or 3/3.3 V operation



• Programmable alarm with repeat mode

• Programmable square-wave output • 1 Hz to 32 KHz


MiCroproCESSor SupErviSor funCTionS • Power-on reset/low-voltage detect

• Programmable watchdog • 62.5 ms to 128 s

• Two reset inputs

appLiCaTion ExaMpLES • Servers

• Medical equipment

• Point of sales

• Vending machines

• Gaming

44 BytesNVRAM

Seconds0.1 Seconds0.01 SecondsCentury bitsCalibrationWatchdog

AlarmSquare wave

MinutesHoursDateDay

MonthYear

VCC

VCC

Microprocessor

VCC

VCC

WDI

VSS

VBAT

SPISPI

I/O

4

Power-on reset/low-voltage detectPush-button resetWatchdog reset

M41T94

Automaticbattery

switchover

Batterymonitor

Power-faildetect and

writeprotect

Power-failTHSThreshold

32 KHzoscillator

XTAL

RSTRESET

IRQ

IRQ/FT/OUT

SQW

WDF

AF

RSTIN1RSTIN2

1: VPFD = 4.40 V0: VPFD = 2.65 V

SO16

SOH28

SNAPHAT battery top

11

M41ST85w• 400 kHz I2C


• 2.7 to 3.6 V

• 28-lead SNAPHAT® IC (SOH28)

• 28-lead embedded crystal SOIC (SOX28)

• Operating temperature: -40 to +85 °C


• Programmable alarm with repeat mode



MiCroproCESSor SupErviSor funCTionS• Early power-fail warning (PFI/PFO)

with 1.25 V reference


• Programmable watchdog • 62.5 ms to 128 s

• Two reset inputs

nvraM SupErviSor fEaTurES• Automatic battery switchover and

write-protect • Non-volatile external LPSRAM

• Battery monitor

XTAL

RSTIN1RSTIN2

IRQ/FT/OUTWDFAF

44 BytesNVRAM

Seconds0.1 Seconds0.01 SecondsCentury bitsCalibrationWatchdog

AlarmSquare wave

MinutesHoursDateDay

MonthYear

R1

R2

VCC VCC

LPSRAM256 Kb

to 16 Mb

VOUT

VSS

VBAT

VUNREG

WDI

Power-on reset/low-voltage detectPush-button resetWatchdog reset

M41ST85W

Battery monitorPower-fail

deselect andwrite protect

Real-time clock section

32 KHzoscillator

RST

EX

ECON

SQW

PFO

Early power-failwarning 1.25 V

PFI

VCC

VCC

VUNREG

VPFIMicroprocessor

I/O

ADDR/DATA BUS

RESET

CECE

IRQ

NMI

400 kHz I²CI²C

Regulator Battery backupswitchover

2/4

SNAPHAT battery top

SOH28 SNAPHAT IC

SOX28 Embeddedcrystal (internal view)

12

SECuriTizorCombined real-time clock (RTC) IC including microprocessor supervisor, NVRAM supervisor, with physical tamper detect, plus internal and external RAM clear for secure applications.

M41ST87w • 64-bit unique serial number

• -40 to +85 °C

• 3 V, 3.3 V, 5 V operation


• 28-lead embedded crystal IC

• Counters for 10ths and 100ths of seconds, seconds, minutes, hours, day, date, month, year, and century

• 128 bytes of clearable NVRAM

• Programmable alarm with repeat modes functions in battery-backed mode


• Dedicated 32 KHz output

TaMpEr CirCuiT fEaTurES • Two independent inputs detect circuit

opening or closing. Options on alarm: • Generate interrupt • Clear internal RAM • Clear external RAM • Store event time (always) • Output reset

• Tamper detect functions even in battery-backed mode

• Oscillator fail detect bit indicates oscillator has slowed, and crystal may have been tampered

MiCroproCESSor SupErviSor funCTionS • Programmable watchdog • 62.5 ms to 128 s timeout period


• Two reset input pins

• Two independent early power-fail warning circuits (PFI/PFO) with 1.25 V precision reference

nvraM SupErviSor fEaTurES • Battery switchover

• Power-fail write protect

• Battery monitor

• Turns LPSRAM into NVRAM

appLiCaTion ExaMpLES • Black boxes

• Closed-circuit TV

• Financial security: ATM, cash, registers, POS, card readers

• Gaming machines

• Fire alarms

• Metering (gas, electricity, water)

SOX28 Embedded crystal(internal view)

SSOP20

M41ST87w appLiCaTion diagraM

128 BytesNvram

Seconds0.1 Seconds0.01 SecondsCentury bitsCalibration

AlarmWatchdog

Square wave64 bit ser. no.

MinutesHoursDateDay

MonthYear

Power-on reset/low-voltage detect

Early power-failwarning (PFI/PFO)

Watchdog

Interrupt

EXT RAM CLR

INT RAM CLR

VCC VBAT

Microprocessor/Microcontroller

/CE

TP1INTP2IN

I²C

Batteryswitchover

Writeprotect

LPSRAM

13

part number

pack

age

battery supply current

(ibat)

nvraMsize data

bus type

vCC

batte

rysw

itcho

ver

osci

llato

r fai

l de

tect

prog

ram

mab

leal

arm

s

Squa

re w

ave

dedi

cate

d ou

tput

pow

er-u

p ou

tput

fr

eque

ncy

(kHz

)

wat

chdo

gtim

er

batte

ry lo

w

dete

ct

pow

er o

nre

set/

low

volta

ge d

etec

tor

outp

ut

pow

er f a

il co

mpa

rato

r

rese

t inp

uts

Embe

dded

cry

stal

typ (na) (bytes)min -

max (v)

M41ST85wSOX-28 400 44 I²C2 2.7 - 3.6 •4 - •3 • - •3 • • • • •

SOH-28 400 44 I²C2 2.7 - 3.6 •4 - •3 • - •3 • • • • •

M41ST87wSSOP 20 500 128 I²C2 2.7 - 3.6 •4 •3 •3 • 32 •3 • • • • •

SOX-28 500 128 I²C2 2.7 - 3.6 •4 •3 •3 • 32 •3 • • • • •

M41T94SO-16 400 44 SPI1 2.7 - 5.5 •4 • •3 • - •3 • • - • •

SOH-28 400 44 SPI1 2.7 - 5.5 •4 • •3 • - •3 • • - • •

Note:1: 2 MHz2: 400 kHz3: With IRQ output4: Fixed switchover reference

HigHLy-inTEgraTEd rTCs porTfoLio

RSTIN1RSTIN2

Tamper ckt 2

128 bytesuser ramWatchdog

Real-time clockwith alarm

Osc monitorSquare wave

64 bitserial numberTamper ckt 1

R1

R2

VCCVCC

Any size -256 Kbytes

to 16 Mbytes

LPSRAMVOUT

VSS

VBAT

VUNREG

WDI

M41ST87W

Real-time clock section

XTAL

TP1INTP2IN

RST

ECON

SQW

TPCLR

/BLRAMCLR

WD

TD1TD2

AF

OF(R

ESET

ON

W-D

OG)

(RES

ET O

N TP

CLR)

IRQ/OUT

PFO1

PFO2

1.25 VREF

PFI1

PFI2

VUNREG

VPFI

ADDR/DATA BUS

EX CE

Debounce

400 KHzI²C interface

32 KHz

Regulator

Power-faildeselect andwrite protect

2

VCC

Microprocessor

RESET

CE

IRQ

NMI

I²C

WDI

Compare

Compare

32 KHzoscillator

Power-failwrite protect

Battery monitor

14

part number packagepackage

sizevCC

min - max ibat typ

Timekeeping min

nvraM oscillator fail detect

features(mm) (v) (na) (v) (bytes)

M41T60 QFN16 3.0x3.0 1.3 - 4.4 350 1 - • I²C

M41T62LCC8

QFN161.5x3.2 3.0x3.0

1.3 - 4.4 350 1 - •Dedicated SQW output, crystal, I2C, programmable alarm,

SQW @ 32 kHz, WDG

M41T63 QFN16 3.0x3.0 1.3 - 4.4 350 1 - •Dedicated SQW and WDG timer output, crystal, I2C,

programmable alarm, SQW @ 32 kHz

M41T64 QFN16 3.0x3.0 1.3 - 4.4 350 1 - •Dedicated SQW output, I2C, programmable alarm,

SQW @ 32 kHz, WDG

M41T65 QFN16 3.0x3.0 1.3 - 4.4 350 1 - • Dedicated WDG timer output, I²C, programmable alarm

M41T66 QFN16 3.0x3.0 1.5 - 4.4 525 1 - •Dedicated SQW output I²C, programmable alarm,

SQW @ 32 kHz, WDG,

M41T0 SO-8 3.9x4.9 2 - 5.5 900 2 - • I²C

M41T00S SO-8 3.9x4.9 2.7 - 5.5 600 2 - • Battery switchover with fixed reference, I²C

M41T00aud DFN16 4.0x5.0 3 - 3.6 600 1.7 - •Battery switchover with fixed reference,

integrated audio amplifier, I²C

M41T00Cap PCDIP24 17.8x 34.3 2.7 - 5.5 - - - •Battery switchover with fixed reference,

integrated battery, I2C, crystal

M41T11SO-8

SOH-283.9x4.9 8.2x17.8

2 - 5.5 800 2 56 - Battery switchover, SNAPHAT package available, I²C

M41T56 SO-8 3.9x4.9 4.5 - 5.5 450 2.5 56 - I²C

M41T80 SO-8 3.9x4.9 2 - 5.5 1500 2 - - Battery switchover, I²C, programmable alarm, SQW

M41T81 SO-8 3.9x4.9 2 - 5.5 600 2 - -Battery switchover, low battery detection, I²C,

programmable alarm, SQW, WDG

M41T81SSO-8

SOX-183.9x4.9 7.6x11.6

2.7 - 5.5 600 2 - •Battery switchover with fixed reference, low battery detection,

crystal, I²C, programmable alarm, SQW, WDG

M41T82 SO-8 3.9x4.9 2.38 - 5.5 365 1.8 12 •Analog calibration, battery switchover with fixed reference,

low battery detection, I²C, POR/LVD

M41T83QFN16 SOX-18

4.0x4.0 7.6x11.6

2.38 - 5.5 365 1.8 12 •Analog calibration, battery switchover with fixed reference,

low battery detection, I²C, programmable alarm, SQW @ 32 kHz, WDG, POR/LVD

M41T93QFN16 SOX-18

4.0x4.0 7.6x11.6

2.38 - 5.5 365 1.8 12 •Analog calibration, battery switchover with fixed reference,

low battery detection, crystal, 10 MHz SPI, programmable alarm, SQW @ 32 kHz, WDG, POR/LVD

M41ST85wSOH28 SOX-28

8.2x17.7 17.9x7.6

2.7 - 3.6 400 - 44 -

Battery switchover with fixed reference, low battery detection, microprocessor supervisor functions, crystal,

SNAPHAT package, I²C, programmable alarm, SQW, WDG, POR/LVD, PFI/PFO, RSTin

M41ST87wSOX-28 SSOP20

7.6x17.9 5.3x7.2

2.7 - 3.6 500 - 128 •

Battery switchover with fixed reference, low battery detection, microprocessor supervisor functions, tamper detection, I²C,

programmable alarm, SQW @ 32 kHz, WDG, POR/LVD, PFI/PFO, RSTin

M41T94SO16

SOH283.8x9.8 8.2x17.7

2.7 - 5.5 400 - 44 -

Battery switchover with fixed reference, low battery detection, microprocessor supervisor functions, snaphat package,

2 MHz SPI, programmable alarm, SQW, WDG, POR/LVD, RSTin

M41TC8025 S0-14 9.90 x 5.30 1.6 - 5.5 800 1.6 - -Temperature compensated, Low battery detection, I²C,

programmable alarm, SQW, Fout 1 Hz-1 KHz-32 KHz, POR/LVD

SEriaL rEaL-TiME CLoCkS porTfoLio

15

SnapHaT® paCkagingSerial real-time clocks are packaged in a special SNAPHAT SOIC which mates with ST’s SNAPHAT battery/crystal top. The SNAPHAT top can be removed and replaced allowing the user to extend the battery backup time indefinitely.

SnapHaT® TopS, baTTEry and CrySTaL inTEgraTEd

EMbEddEd CrySTaL paCkagingThe 32 KHz crystal is encapsulated in the serial real-time clock IC package. This allows the crystal to be less sensitive to humidity, temperature and vibration with the benefit of being a surface mount solution. It also enhances security by shielding the crystal from tampering.

48 mAh 120 mAh

M4T28-BR12SH M4T32-BR12SH

SOX28 Embedded crystal(internal view)

SOX18Embedde crystal(internal view)

gLoSSary

function description

Timekeeping supply voltage Minimum oscillator operating voltage for specified temperature range.

programmable alarmsAn alarm which can be set for a specified date and time, or to repeat at a certain day of every month, or at a certain hour of every day, or at a certain minute of every hour, or a certain second of every minute.

Square wave output (SQw) A user programmable square wave signal with rail-to-rail amplitude and 50% duty cycle which is output on the SQW pin.

oscillator fail detectA flag bit used to indicate that the oscillator has either stopped, or was stopped for some period of time and can be used to judge the validity of the clock and date data.

power-up output frequency (f32k)A special 32 kHz square wave function which is enabled on power-up to output on the F32K pin. Some devices offer this power-up default signal on the SQW pin.

battery switchover (vSo)The voltage threshold at which the device power is switched to the back-up battery supply when VCC falls. At this time the clock registers is maintained by the attached battery supply. As system power returns and VCC rises above VSO, the battery is disconnected, and the power supply is switched to external VCC.

watchdog timer (wdg)The watchdog timer is 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.

battery low detect (bL)Battery low detect is an automatic comparison of the battery voltage with a reference voltage of ~2.5 V. If the battery voltage is found to be less than 2.5 V, a flag is set and clock data should be considered suspect and verified as correct. A fresh battery should be installed.

power on reset/low voltage detector output (por/Lvd)

A continuous monitor of the VCC supply. When VCC falls to the power fail detect threshold, the /RST output pulls low and remains low for a defined recovery time after power-up,

power fail comparator (pfi/pfo) This function is intended for use as an early warning undervoltage detector to signal a failing power supply.

reset inputs (rSTin) Independent inputs which can generate an output reset which is identical to a reset generated by a power cycle.

paCkagE opTionS

LCC81.5 mm x 3.2 mmEmbedded crystal

QFN163 mm x 3 mm

QFN164 mm x 4 mm

DFN165 mm x 4 mm

SO83.80 mm x 4.80 mm

SO149.9 mm x 5.3 mmEmbedded crystal

SO163.80 mm x 9.80 mm

SSOP207.2 mm x 5.3 mm

PCDIP24 CAPHAT™34.29 mm x 17.83 mmSelf-contained battery

and crystal (internal view)

SOX1811.61 mm x 7.62 mm

Embedded crystal SOIC

SOX2818.01 mm x 7.67 mm

Embedded crystal

SOH2817.71 mm x 8.23 mm

SNAPHAT™:Battery and crystal snap on module to order separately (internal view)

© STMicroelectronics - December 2012- Printed in United Kingdom - All rights reservedThe STMicroelectronics corporate logo is a registered trademark of the STMicroelectronics group of companies

All other names are the property of their respective owners

For more information on ST products and solutions, visit www.st.com/rtcOrder code: BRRTC1212

Real-time clocks application notes, technical notes, online calculators and resources

Readers will find these documents helpful in understanding some of the subtleties of RTCs and what it takes to keep them running reliably.

Design support

application notes

an922 Using a super cap to back up the M41T56, M41T00, M41T11, M41T81, M41T94 and M41ST84W (16-pin)

an923 Timekeeper rolling into the year 2000 (21st century, Y2K)

an1011 Battery technology used in NVRAM and real-time clock (RTC) products from ST

an934 How to use the digital calibration feature in Timekeeper® and serial real-time clock (RTC) products

an1012 Predicting the battery life and data retention period of NVRAMs and serial RTCs

an1879 How to use M41ST87 tamper detect and RAM clear

an1572 Power-down time-stamp function in serial real-time clocks (RTCs)

an2583 Understanding and applying the M41T00AUD real-time clock with audio

an2678 Extremely accurate timekeeping over temperature using adaptive calibration

an2971 Using the typical temperature characteristics of 32 KHz crystal to compensate the M41T83 and the M41T93 serial real-time clocks

an3060 Applications guide for serial real-time clocks (RTCs)

Technical note

Ta0344 Highly accurate, automatic temperature-compensated real-time clock (RTC) solution

produCT SupporT aT HTTp://www.ST.CoM/rTC • Datasheets

• Application notes

• Selector tables

• Serial RTC example code

• UL information

• Clock calibration tools

• RTC and NVRAM model files

• Design support calculators @ www.st.com/calculators

• Online technical support

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