A DC-DC converter, which provides a converter output voltage using a DC source voltage, is disclosed. The DC-DC converter includes converter control circuitry and a boosting charge pump. The converter control circuitry selects one of a first boost operating mode, a second boost operating mode, and a boost disabled mode based on the DC source voltage. During the boost disabled mode, the boosting charge pump presents a high impedance at a charge pump output of the boosting charge pump. Otherwise, the boosting charge pump provides a charge pump output voltage. During the first boost operating mode, a nominal value of the charge pump output voltage is equal to about one and one-half times the DC source voltage. During the second boost operating mode, a nominal value of the charge pump output voltage is equal to about two times the DC source voltage.