The ISL91127 and ISL91127IR are high-current buck-boost switching regulators for systems using new battery chemistries. These devices use Renesas' proprietary buck-boost algorithm to maintain voltage regulation while providing excellent efficiency and very-low output voltage ripple when the input voltage is close to the output voltage. They are capable of delivering at least 2A of continuous output current (VOUT = 3.3V) over a battery voltage range of 2.5V to 4.35V. This maximizes the energy utilization of advanced single-cell Li-ion battery chemistries that have significant capacity left at voltages below the system voltage. Its fully synchronous low ON-resistance, 4-switch architecture, and a low quiescent current of only 30µA, optimize efficiency under all load conditions. The ISL91127 and ISL91127IR support stand-alone applications with a fixed 3.3V or 3.5V output voltage or adjustable output voltage with an external resistor divider. Output voltages as low as 1.0V or as high as 5.2V are supported. The ISL91127 is available in a 20-bump, 0.4mm pitch WLCSP (2.15mm x 1.74mm) package, and the ISL91127IR is available in a 20 Ld, 0.5mm pitch QFN (4mm x 4mm) package. The 2.5MHz switching frequency further reduces the size of external components.