Demonstration Circuit DC1658A is a 20V High Efficiency Nanopower Step-Down Regulator featuring the LTC3388-1/ LTC3388-3. The LTC3388 is an ultralow quiescent current power supply designed to regulate the output voltage by means of a nanopower high efficiency synchronous buck regulator. The input current is only 720nA typical at no load while maintaining output voltage regulation, capable of supplying 50mA of load current. The LTC3388-1/ LTC3388-3 also in-corporates an accurate undervoltage lockout feature to disable the converter and maintain a low quiescent current state when the input voltage falls below 2.3V. In regulation, the LTC3388-1/LTC3388-3 enter a sleep state in which both input and output quiescent currents are minimal. The buck converter turns on and off as needed to maintain regulation. An additional standby mode disables the buck switching while the output is in regulation for short duration loads requiring low ripple.