The RP100x Series are CMOS-based voltage regulator ICs with high output voltage accuracy, extremely low supply current, low ON-resistance, and high ripple rejection. Each of these ICs consists of a voltage reference unit, an error amplifier, resistor-net for voltage setting, a current limit circuit, and a chip enable circuit. These ICs perform with low dropout voltage and a chip enable function. The line transient response and load transient response of the RP100x Series are excellent, thus these ICs are very suitable for the power supply for hand-held communication equipment. The output voltage of these ICs is fixed with high accuracy. Since the packages for these ICs are SOT-23-5 and PLP1612-4, therefore high density mounting of the ICs on boards is possible.