A common power-supply requirement involves converting a 2.4- or 3-V battery voltage to a 5-V logic suppl
y. This circuit converts 3 V to 5 V at 40 mA with 85% efficiency. When Ic (pin 6) is driven low, the output voltage will be the battery voltage minus the drop across diode Dl. The optional circuitry that uses CI, R3, and R4 lowers the oscillator frequency when the battery voltage falls to 2.0 V. This lower frequency maintains the output-power capability of the circuit by increasing the peak inductor current, which compensates for the reduced battery voltage.