M41ST85W_11 datasheet(1/43 Pages) STMICROELECTRONICS

Part #	M41ST85W

Description	3.0/3.3 V I2C combination serial RTC, NVRAM supervisor and microprocessor supervisor

PDF	43 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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1 / 43 page

October 2011

Doc ID 7531 Rev 11

1/43

1

M41ST85W

3.0/3.3 V I2C combination serial RTC, NVRAM

supervisor and microprocessor supervisor

Features

■ Automatic battery switchover and WRITE

protect for:

– Internal serial RTC and

– External low power SRAM (LPSRAM)

■ 400 kHz I2C serial interface

■ 3.0/3.3 V operating voltage

–VCC = 2.7 to 3.6 V

■ Ultralow battery supply current of 500 nA (max)

■ RoHS compliant

– Lead-free second level interconnect

Serial RTC features

■ 400 kHz I2C

■ 44 bytes of general purpose NVRAM

■ Counters for:

– Seconds, minutes, hours, day, date, month,

and year

–Century

– Tenths/hundredths of seconds

– Clock calibration register allows

compensation for crystal variations over

temperature

■ Programmable alarm with repeat modes

– Functions in battery back-up mode

■ Power-down timestamp (HT bit)

■ 2.5 to 5.5 V oscillator operating voltage

Microprocessor supervisor features

■ Programmable watchdog

– 62.5 ms to 128 s time-out period

■ Early power-fail warning circuit (PFI/PFO) with

1.25 V precision reference

■ Power-on reset/low voltage detect

– Open drain reset output

– Reset voltage, VPFD = 2.60 V (nom)

– Two reset input pins

– Watchdog can be steered to reset output

NVRAM supervisor features

■ Non-volatizes external LPSRAM

– Automatically switches to back-up battery

and deselects (write-protects) external

LPSRAM via chip-enable gate

– Power-fail deselect (write protect) voltage,

VPFD = 2.60 V (nom)

– Switchover, VSO = 2.50 V (nom)

■ Battery monitor (battery low flag)

Other features

■ Programmable squarewave generator (1 Hz to

32 KHz)

■ –40°C to +85°C operation

■ Package options:

– 28-lead SNAPHAT® IC (SOH28) SNAPHAT

battery/crystal top to be ordered separately

– 28-lead embedded crystal SOIC (SOX28)

28

1

SNAPHAT battery & crystal

SOH28

Embedded crystal

SOX28

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M41ST85W Datasheet(PDF) 1 Page - STMicroelectronics

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