The XC6601 series is a low voltage input CMOS LDO regulator which provides highly accurate (20mV) outputs and can supply current efficiently due to its ultra low on-resistance even at low output voltages. The series is ideally suited to the applications which require very low dropout voltage operation and consists of a voltage reference, an error amplifier, a driver transistor, a current limiter, a fold back circuit, a thermal shutdown (TSD) circuit, an under voltage lock out (UVLO) circuit, soft-start circuit and a phase compensation circuit. Output voltage is selectable in 0.05V increments within a range of 0.7V to 1.8V using laser trimming technology and ceramic capacitors can be used for the output stabilization capacitor (CL). The over current protection circuit (the current limiter and the fold back circuit) as well as the thermal shutdown circuit (the TSD circuit) are built-in. These two protection circuits will operate when either the output current reaches the current limit level or the junction temperature reaches the temperature limit level. With the built-in UVLO function, the regulator output is forced OFF when the voltage level at the VBIAS pin or the VIN pin falls below the UVLO voltage level. With the soft-start function, the inrush current from VIN to VOUT for charging CL at start-up can be reduced and makes the VIN stable. The CE function enables the output to be turned off and the series to be put in stand-by mode resulting in greatly reduced power consumption. At the time of entering the stand-by mode, the series enables the electric charge at the output capacitor (CL) to be discharged via the internal auto-discharge switch which is located between the VOUT pin and the VSS pin. As a result the VOUT pin quickly returns to the VSS level.