Patent ID: 7948282

Claim:
A triangular wave generation circuit, comprising: a capacitor whose potential is fixed at one end thereof; a charge-discharge circuit which charges or discharge said capacitor; a first comparator which compares an output voltage appearing at the other end of said capacitor with a predetermined maximum threshold voltage and which outputs a first comparison signal in response to a comparison result; a second comparator which compares the output voltage with a predetermined minimum threshold voltage that is lower than the maximum threshold value and which outputs a second comparison signal in response to a comparison result; an edge detection circuit which detects an edge of a synchronization signal, inputted externally, having approximately ½ of frequency of a triangular wave signal generated by said triangular wave generation circuit and which outputs an edge detection signal that becomes a predetermined level for each edge; and a charge-discharge control unit which refers to the first and the second comparison signal outputted from said first and said second comparator, respectively, and which sets said charge-discharge circuit to a discharging state when the output voltage becomes higher than the maximum threshold voltage and which sets said charge-discharge circuit to a charging state when the output voltage becomes lower than the minimum threshold voltage, wherein when the edge detection signal outputted from said edge detection circuit becomes the predetermined level, said charge-discharge control unit switches the charging and the discharge state of said charge-discharge circuit.