The BD83070GWL is a synchronous buck-boost DC/DC convertor providing 3.3 V or 2.5 V output from single-cell Li-ion battery or other input between 2.0 V and 5.5 V. It has the capability to support up to 1 A output over input voltage range of 2.7 V to 5.5 V. It seamlessly changes between buck and boost operations depending on the input voltage. It is based on pulse width modulation (PWM) and provides high efficiency for heavy load. While in PWM operation, internal FETs switch at fixed frequency 1.5MHz typical. It automatically changes over control system to hysteresis pulse frequency modulation (PFM) to suppress switching loss and current consumption during light load. Battery drain fall down to only 2.8 μA typical at no load current. It is possible to disable auto-PFM/PWM mode by the MODE pin for suppressing output ripple and fixed frequency switching. The device is packaged in a 1.2 mm x 1.6 mm WLCSP package.