M41ST85WMH6

NVRAM串行RTC

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