X5168, X5169 pdf datasheet (CP

These devices combine three popular functions, Power-on
Reset Control, Supply Voltage Supervision, and Block Lock
Protect 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/RESET active for a period of
time. This allows the power supply and oscillator to stabilize
before the processor can execute code.
The device’s low VCC detection circuitry protects the user’s
system from low voltage conditions by holding
RESET/RESET active when VCC falls below a minimum VCC
trip point. RESET/RESET remains asserted until VCC returns
to 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 fine-tune the threshold in
applications requiring higher precision.