Patent ID: 8198881

Claim:
A chopper type DC-DC converter comprising: a voltage converting circuit configured to convert a first voltage into a second voltage; a comparative wave generating circuit configured to generate a first comparative wave and a second comparative wave such that a voltage range of said first comparative wave is different from a voltage range of said second comparative wave; a comparator group configured to generate a first comparison result signal indicating a result of comparison between said first comparative wave and an error signal indicating an error between said second voltage and target voltage and a second comparison result signal indicating a result of comparison between said second comparative wave and said error signal; and a switch control circuit configured to control said voltage converting circuit based on said first comparison result signal and said second comparison signal, wherein said comparative wave generating circuit includes a first comparative wave generating circuit and a second comparative wave generating circuit, and said first comparative wave generating circuit and said second comparative wave generating circuit respectively generate said first comparative wave and said second comparative wave based on different source voltage groups, wherein said voltage range of said first comparative wave is from a second reference voltage to a first reference voltage, and said voltage range of said second comparative wave is from a third reference voltage to said second reference voltage, and said first reference voltage is higher than said second reference voltage, and said third reference voltage is lower than said second reference voltage, wherein said first comparative wave generating circuit includes: a first capacitor having a first electrode connected to a first output terminal of said first comparative wave generating circuit; a first charging and discharging circuit connected to said first electrode and configured to charge or discharge said first capacitor at a constant current; and a first charging and discharging control circuit configured to switch said first charging and discharging circuit between charging mode and discharging mode, and said second comparative wave generating circuit includes: a second capacitor having a second electrode connected to a second output terminal of said second comparative wave generating circuit; a second charging and discharging circuit connected to said second electrode and configured to charge or discharge said second capacitor at a constant current; and a second charging and discharging control circuit configured to switch said second charging and discharging circuit between charging mode and discharging mode.