Voltage regulators

A voltage regulator and method of operating a voltage regulator, suitable for battery powered devices where power efficiency at low load currents is important, includes a first portion comprising a low-dropout (LDO) regulator 104, and a second portion comprising an energy storage device 116. The LDO regulator is powered up at least until the output 120 of the voltage regulator reaches a predetermined value, and during power up the energy storage device is charged. The LDO regulator is subsequently powered down until the voltage regulator output 120 has dropped by a predetermined amount, at which point the LDO regulator power up begins again. During LDO regulator power down, current to the load is supplied by the energy storage device, which may be a capacitor. The predetermined voltage value may be provided by a reference circuit, such as a band-gap circuit, and the reference circuit may be powered selectively based on the output voltage of the LDO regulator. A control circuit 140 may be included to control the powering up and down of the LDO regulator and/or voltage reference circuit.