RP173x Series Low Dropout Regulators Nisshinbo RP173x Series Low Dropout Regulators are CMOS-based LDOs featuring a 150mA output and a low supply current of 2.0µA. The RP173x LDOs integrates a voltage reference unit, an error amplifier, a resistor-net for voltage setting, a current limit circuit, a chip enable circuit and a reverse current protection circuit. The A version of the RP173x includes a CE (chip enable) input pin with reduced CE pull-up resistance to make its supply current ultra-low.