The ADP2108 is a high efficiency, low quiescent current stepdown dc-to-dc converter in an ultrasmall 5-ball WLCSP package. The total solution requires only three tiny external components. It uses a proprietary, high speed current mode, constant frequency PWM control scheme for excellent stability and transient response. To ensure the longest battery life in portable applications, the ADP2108 has a power save mode that reduces the switching frequency under light load conditions. The ADP2108 runs on input voltages of 2.3 V to 5.5 V, which allows for single lithium or lithium polymer cell, multiple alkaline or NiMH cell, PCMCIA, USB, and other standard power sources. The maximum load current of 600 mA is achievable across the input voltage range.