Features

· Automatic battery switchover and WRITE

protect for:

– Internal serial RTC and

– External low power SRAM (LPSRAM)

· 32 kHz crystal oscillator integrating load

capacitance (12.5 pF) providing exceptional

oscillator stability and high crystal series

resistance operation

· 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)