Power supply device and light-emitting element drive device

A light emitting element drive device, comprising:

• a converter that supplies electric power by performing an ON and OFF operation of a switching element;
• a light emitting element that is driven by the electric power supplied from the converter;
• a current detector that detects a current value of a current flowing in the light emitting element;
• a conversion circuit that converts the current value into a digital value;
• an arithmetic circuit that receives an operation clock signal and that calculates a control command value based on the digital value from the conversion circuit;
• a pulse signal generation circuit that outputs a pulse signal of a duty ratio that is determined based on the control command value;
• a ramp signal generation circuit that outputs a ramp signal synchronized to a clock signal generated based on the operation clock signal;
• an integration circuit that receives the pulse signal and that outputs an output voltage;
• and
• a driving signal generation circuit that generates a driving signal based on a comparison result of the ramp signal with the output voltage from the integration circuit, wherein
• the switching element performs the ON and OFF operation according to the driving signal.