RT9801A/RT9801B pdf datasheet

The RT9801A/B is a micro-power voltage detector
supervising the power supply voltage level for
microprocessors (μP) or digital systems. It provides user
programmable threshold levels with 0.1V step ranging
from 1.5V to 5V, which covers most digital applications. It
features low supply current of 3μA. Selection of VTH is
easily achieved through 3 pins connected to GND, VDD or
floating for different threshold voltage settings. Two versions
of threshold voltages, 1.5V to 4V and 2.5V to 5V, which
are programmed in factory are offered by customer
demands.
The RT9801A/B performs supervisory function by sending
out a reset signal whenever the VDD voltage falls below a
preset threshold level. This reset signal will last the whole
period before VDD recovering. Reset signal will release after
VDD is recovered and last for the whole period of Reset
Active Time-out period.
RT9801A/B is N-Channel, open-drain output and provided
in SOT-23-6 package.