The selectable operation mode between forced PWM mode and automatic PWM/PFM mode maximizes battery life in portable and handheld applications. The low quiescent current of 17 μA to 40 μA in a light load/stand-by condition makes this family of regulators ideal for battery powered applications and other “Green Power” applications. The 100% duty cycle also extends the system life when the battery output begins to droop. In addition to integrating a pair of low ON-resistance switching MOSFETs and the small package size, these solutions save space by featuring a 1 MHz (1.6 MHz for ISL8009A) switching frequency that allows the use of smaller external components. These devices also feature internal current mode compensation to further eliminate the need for external components while enabling a fast transient response and high duty cycle/low drop-out operation. External synchronization up to 4 MHz (for ISL8013 and ISL8014) reduces electromagnetic emissions between multiple rails on the system board. Features such as power-on-reset (POR), power-good (PGOOD) and enable (EN) provide output voltage monitoring and power sequencing capabilities without the need for additional discrete ICs.