Patent ID: 8018364
Filing Date: 2011-09-13
Classification: H03M

Abstract:
1. A control apparatus to control a supply device, the apparatus comprising: a digitizer circuit adapted to digitize a supply voltage and provide a first digital signal; and a sigma-delta device having an input terminal configured to receive a second digital signal and produce a pulse density modulation signal at an output terminal of the sigma-delta device, the sigma-delta device including a feedback circuit coupled to the input terminal of the sigma-delta device and configured to send a third digital signal having a value that depends on a value of the pulse density modulation signal, the feedback circuit including a terminal to receive the first digital signal, the sigma-delta device having a gain and configured to produce the pulse density modulation signal proportional to the inverse of the first digital signal, the feedback circuit including a device structured to supply the third digital signal with a first value or the value of the further digital signal if respectively the value of the pulse density signal at the output from the sigma-delta device has respectively a second value or the first value, a subtractor structured to subtract the third digital signal from the second digital signal to provide a fourth digital signal, the sigma-delta device further including an integrator structured to integrate the fourth digital signal and a comparator structured to compare a digital output signal at an output of the integrator with the first digital signal to provide the pulse density modulation signal of the sigma-delta device with the second value if the digital output signal at the output of the integrator is lower than the first digital signal and with the first value if the digital output signal at the output of the integrator is equal to or greater than the further digital signal.