A portable electronic device adapted to be worn, at least partly, in or at a human ear, comprising a low voltage power supply providing a low voltage power supply output voltage and a boost converter (102, 500), wherein said boost converter (102, 500) is adapted for increasing the low voltage power supply output voltage to a level suitable to power the portable electronic device, - wherein said boost converter (102, 500) is powered by the low voltage power supply, wherein said low voltage power supply is not capable of providing an output voltage of a level sufficient to operate the portable electronic device CHARACTERIZED IN THAT - the boost converter (102, 500) further comprises a digital duty cycle generator and an analog pulse-width modulation generator, both generators being configured to generate a duty cycle modulated clock signal for driving the boost converter (102, 500), - wherein the digital duty cycle generator is adapted for driving the boost converter (102, 500) with a low supply voltage and comprises means for sampling the low voltage power supply output voltage or the boost converter output voltage and means for adjusting the duty cycle of a digital clock signal in response to the value of said sampled voltage, - wherein the analog pulse-width modulation generator is adapted for driving the boost converter (102, 500) with high stability of the boosted voltage, and - wherein the boost converter (102, 500) is configured to use the digital duty cycle generator for generating the duty cycle modulated clock signal to drive the boost converter (102, 500) when the portable device is in a start-up mode and to use the analog pulse-width modulation generator for generating the duty cycle modulated clock signal when the portable electronic device is in a normal mode of operation. - wherein said boost converter (102, 500) is powered by the low voltage power supply, wherein said low voltage power supply is not capable of providing an output voltage of a level sufficient to operate the portable electronic device CHARACTERIZED IN THAT - the boost converter (102, 500) further comprises a digital duty cycle generator and an analog pulse-width modulation generator, both generators being configured to generate a duty cycle modulated clock signal for driving the boost converter (102, 500), - wherein the digital duty cycle generator is adapted for driving the boost converter (102, 500) with a low supply voltage and comprises means for sampling the low voltage power supply output voltage or the boost converter output voltage and means for adjusting the duty cycle of a digital clock signal in response to the value of said sampled voltage, - wherein the analog pulse-width modulation generator is adapted for driving the boost converter (102, 500) with high stability of the boosted voltage, and - wherein the boost converter (102, 500) is configured to use the digital duty cycle generator for generating the duty cycle modulated clock signal to drive the boost converter (102, 500) when the portable device is in a start-up mode and to use the analog pulse-width modulation generator for generating the duty cycle modulated clock signal when the portable electronic device is in a normal mode of operation.