Patent ID: 8093874

Claim:
A buck (with boost) switcher, comprising: an integrated circuit configured to receive a power supply voltage and a mode signal and to generate a boost voltage, a boost current or a buck voltage based on the power supply voltage and the mode signal, the mode signal corresponding to one of a buck mode and a boost mode; and a single inductor coupled to the integrated circuit and configured to be used by the integrated circuit to generate the boost voltage or the boost current in the boost mode and to generate the buck voltage in the buck mode; wherein the integrated circuit comprises a maximum voltage selector configured to select one of the power supply voltage and the boost voltage as a maximum voltage for use in operating the switcher, the maximum voltage selector comprising: a comparator configured to compare the power supply voltage and the boost voltage to generate a comparator output; a high-voltage transistor coupled to the comparator and configured to select the boost voltage as the maximum voltage when the comparator output indicates that the boost voltage is greater than the power supply voltage; and a low-voltage transistor coupled to the comparator and configured to select the power supply voltage as the maximum voltage when the comparator output indicates that the power supply voltage is greater than the boost voltage.