A current detection circuit generates a current detection signal VCS that corresponds to a lamp current ILAMP supplied from a switching converter to a semiconductor light source. A hysteresis comparator compares a current detection signal VCS with an upper-side threshold signal VTHH and a lower-side threshold signal VTHL determined according to an analog dimming signal, and generates a control pulse SCNT that corresponds to the comparison result. A driver drives a switching transistor according to the control pulse. A PWM dimming circuit generates a gradual change signal by dulling a PWM (pulse width modulation) dimming signal, and changes the analog dimming signal based on the gradual change signal.
Automotive lamp
2020-07-14
Patent
Electronic Resource
English
IPC: | H01L Halbleiterbauelemente , SEMICONDUCTOR DEVICES / H02M APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS , Anlagen zur Umformung von Wechselstrom in Wechselstrom, von Wechselstrom in Gleichstrom oder umgekehrt, oder von Gleichstrom in Gleichstrom und zur Verwendung in Netzen oder ähnlichen Stromversorgungssystemen / B60Q ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL , Anordnung von Signal- oder Beleuchtungsvorrichtungen, deren Einbau oder Halterung oder deren Schaltkreise bei Fahrzeugen allgemein / H05B ELECTRIC HEATING , Elektrische Heizung |