Patent ID: 8988056
Filing Date: 2015-03-24
Classification: H02M,Y02B

Abstract:
1. A hysteretic power converter comprising: a switched mode power supply comprising an inductor, an electronically controlled switch and an output capacitor, said electronically controlled switch arranged to alternately open and close a loop with said inductor and leads of a power source; a synchronization circuit arranged to synchronize said switched mode power supply with a periodic signal, said synchronization circuit arranged to close said electronically controlled switch responsive to each and every occurrence of a predetermined condition of the periodic signal; a hysteretic comparator, a first input of said hysteretic comparator coupled to a feedback connection and arranged to receive from the feedback connection a feedback signal providing a representation of the voltage across said output capacitor, said electronically controlled switch opened responsive to the output of said hysteretic comparator; a reference voltage source coupled to a second input of said hysteretic comparator and arranged to provide a reference voltage; a ramp capacitor coupled to one of said reference voltage source and said feedback connection; a current source, a terminal of said current source coupled to said ramp capacitor and arranged to drive current to said ramp capacitor; a switchable current source, a terminal of said switchable current source coupled to said ramp capacitor, said switchable current source arranged to drive current to said ramp capacitor in a direction opposite the current driven by said current source, wherein said switchable current source is alternately enabled and disabled responsive to the output of said hysteretic comparator; and an auto-zero circuit coupled across said ramp capacitor and arranged to set the average voltage across said ramp capacitor to zero.