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)