Vehicle lamp and lighting circuit thereof

A lighting circuit for using together with a semiconductor light source and making up a vehicle lamp, comprising:

• a switching converter which supplies power to the semiconductor light source;
• and
• a converter controller which controls the switching converter, wherein the converter controller comprises:
• a current detection circuit configured to detect a current which is supplied from the switching converter to the semiconductor light source;
• a hysteresis comparator configured to compare a detected current value with an upper threshold voltage and lower threshold voltage to generate a control pulse according to the result of the comparison;
• a driver configured to switch a switching element of the switching converter according to the control pulse;
• and
• a threshold voltage generating circuit configured to receive a variable control voltage which indicates a target current amount to generate an upper threshold voltage and a lower threshold voltage according to the control voltage received.