In described examples, a sawtooth waveform generator generates a sawtooth waveform having a first rise time. A comb waveform circuit has a power terminal coupled to receive the sawtooth waveform from an output of the sawtooth waveform generator. The comb waveform circuit generates a comb waveform in response to the sawtooth waveform. The comb waveform has a second rise time that is faster than the first rise time.

In described examples, a sawtooth waveform generator generates a sawtooth waveform having a first rise time. A comb waveform circuit has a power terminal coupled to receive the sawtooth waveform from an output of the sawtooth waveform generator. The comb waveform circuit generates a comb waveform in response to the sawtooth waveform. The comb waveform has a second rise time that is faster than the first rise time.

A wave loss detection circuit includes: an anode of the diode receives a first drive signal, and a cathode of the diode is connected to a first end of the first resistor; a second end of the first resistor is connected to a first end of the first energy storage unit, a first end of the second resistor, and a first input end of the comparison unit; a second end of the first energy storage unit and a second end of the second resistor are connected to a ground level, and a resistance of the first resistor is less than a resistance of the second resistor; a second input end of the comparison unit is configured to receive a threshold voltage, and if a voltage signal received by the first input end is less than the threshold voltage, which indicates that a wave loss occurs in the first drive signal.

A wave loss detection circuit includes: an anode of the diode receives a first drive signal, and a cathode of the diode is connected to a first end of the first resistor; a second end of the first resistor is connected to a first end of the first energy storage unit, a first end of the second resistor, and a first input end of the comparison unit; a second end of the first energy storage unit and a second end of the second resistor are connected to a ground level, and a resistance of the first resistor is less than a resistance of the second resistor; a second input end of the comparison unit is configured to receive a threshold voltage, and if a voltage signal received by the first input end is less than the threshold voltage, which indicates that a wave loss occurs in the first drive signal.