X5083 pdf datasheet (CPU Super

This device combines four popular functions, Power-on Reset
Control, Watchdog Timer, Supply Voltage Supervision, and
Block Lock Serial EEPROM Memory in one package. This
combination lowers system cost, reduces board space
requirements, and increases reliability.
Applying power to the device activates the power-on reset
circuit which holds RESET active for a period of time. This
allows the power supply and oscillator to stabilize before the
processor can execute code.
The Watchdog Timer provides an independent protection
mechanism for microcontrollers. When the microcontroller fails to
restart a timer within a selectable time out interval, the device
activates the RESET signal. The user selects the interval
from three preset values. Once selected, the interval does
not change, even after cycling the power.
The device’s low VCC detection circuitry protects the user’s
system from low voltage conditions, resetting the system
when VCC falls below the minimum VCC trip point. RESET is
asserted until VCC returns to the proper operating level and
stabilizes. Five industry standard VTRIP thresholds are
available, however, Intersil’s unique circuits allow the threshold
to be reprogrammed to meet custom requirements or to finetune
the threshold for applications requiring higher precision.