Start-up Current Overshoot Moderation for a Headlight Driver with a Microcontroller Unit

The laser headlamp driver (LHD) possessing with a DC-DC converter, a feedback controller, and a safety standard circuit, was developed in this study. The buck-boost converter composed of the two-switch and two-diode for the DC-DC converter, which can be implemented in both boost or buck operations. Due to the operating ambient temperature of the laser diode causes the forward bias drift; using the feedback controller, the driving current of the leaser diode could be settled to deal with forward bias drift. In addition, the current overshoot exists when the operation of the buck-boost converter changes to the constant-current from the constant-voltage output mode, during the LHD start-up phase; the current overshoot would be exacerbated when laser diodes operate in the high ambient temperature. In this study, the proportional shifting proportional-integral technology was employed to the current-feedback controller to moderate the start-up current overshoot.