Driving and controlling of blue-beam laser diodes

In this study, a blue-beam laser diode driver (BBLDD) which incorporated the buck-boost converter and feedback controllers, was designed and implemented. The power stage topology was the four-switch buck-boost converter (FSBBC), which could be manipulated in all conversion modes including step-up, step-down, and buck-boost, with variable battery voltages input to the BBLD. Otherwise, the feedback controllers comprised a voltage-loop controller and a current-loop controller; the voltage-loop controller was employed to manipulate the output voltage of FSBBC to drive the blue-beam laser diode (BBLD), and the current-loop controller was employed to control the FSBBC's output current to drive a constant BBLD current. In the initial start-up phase, when the FSBBC is operated from the constant-voltage output mode and changed to the constant-current output mode, a current spike occurs, which would cripple the BBLDs. Thus, a control method, the proportional-switch-proportional-integral control technology, can be applied to the current-loop controller to reduce the current spike.