M41ST85WMH View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M41ST85WMH

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

STMicroelectronics 

M41ST85W

3.0/3.3V 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)

■ 400kHz I2C serial interface

■ 3.0/3.3V operating voltage

– VCC = 2.7 to 3.6V

■ Ultra-low battery supply current of 500nA (max)

■ RoHS compliant

– Lead-free second level interconnect

Serial RTC features

■ 400kHz I2C

■ 44 bytes of general purpose NVRAM

■ Counters for:

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

and year

– Century

– 10ths/100ths 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 5.5V oscillator operating voltage

Microprocessor supervisor features

■ Programmable watchdog

– 62.5ms to 128s time-out period

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

1.25V precision reference

SNAPHAT (SH) battery & crystal

28

1

SOH28 (MH)

Embedded crystal

SOX28 (MX)

■ Power-on reset/low voltage detect

– Open drain reset output

– Reset voltage, VPFD = 2.60V (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 = 2.60V (nom)

– Switchover , VSO = 2.50V (nom)

■ Battery monitor (battery low flag)

Other features

■ Programmable squarewave generator (1Hz to

32KHz)

■ –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)

October 2007

Rev 9

1/41

www.st.com

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