The ADP2118 is a low quiescent current， synchronous， step-down， dc-to-dc regulator in a compact 4mm × 4mm LFCSP package. It uses a current mode， constant frequency pulse-width modulation （PWM） control scheme for excellent stability and transient response. Under light loads， the ADP2118 can be configured to operate in pulse frequency modulation （PFM） mode that reduces switching frequency to save power. The ADP2118 runs from input voltages of 2.3 V to 5.5 V. The output voltage of the ADP2118ACPZ-R7 is adjustable from 0.6 V to input voltage （VIN）， and the ADP2118ACPZ-x.x-R7 are available in preset output voltage options of 3.3 V， 2.5 V， 1.8 V， 1.5 V， 1.2 V， and 1.0 V. The ADP2118 requires minimal external parts and provides a high efficiency solution with its integrated power switch， synchronous rectifier， and internal compensation. The IC draws less than 3 μA from the input source when it is disabled. Other key features include undervoltage lockout （UVLO）， integrated soft start to limit inrush current at startup， overvoltage protection （OVP）， overcurrent protection （OCP）， and thermal shutdown （TSD）.