M41ST85WMX6TR Datasheet PDF - ST Microelectronics

●Description

●The M41ST85W is a combination Serial Real-Time Clock, Microprocessor Supervisor, and NVRAM Supervisor. It is built in a low power CMOS SRAM process and has a 64-byte memory space with 44 bytes of NVRAM and 20 memory-mapped RTC registers (see Table 2 on page 20). The RTC registers are configured in binary coded decimal (BCD) format.

●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

●■ 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