Source switching circuit with low-gate-driving loss in high-voltage buck light emitting diode (LED) driver is proposed in this study. Source switching circuit comprises of a high-voltage power metal-oxide semiconductor field-effect transistor (MOSFET) (HVMOS) and a low-voltage power MOSFET (LVMOS) in series, a capacitor and a Zener diode. By switching the HVMOS by different source voltage and constant gate voltage, it recycles gate charges of HVMOS to reduce gate-driving loss. Gate charges are recycled in the capacitor when LVMOS is turning off, and can be reused when LVMOS is turning on. This circuit also provides a new power feeding route for control chip, and power consumption is relatively low on the proposed route. The power feeding route also improves power efficiency. With a 12 W LED load, the experiment shows that the efficiency of the proposed driving circuit is improved by 3.7% with 156 V input voltage and 4.8% with 326 V input voltage compared with the converter using single HVMOS.

No abstract

No abstract

No abstract

High-intensity and short-duration light is necessary in many applications such as particle image velocimetry and light communication. Using nanosecond current pulse to drive LED or laser diode can generate such light to achieve higher efficiency. In nanosecond current pulse driver design, parasitic inductance effect is a big challenge. Parasitic inductance and voltage across it influence current change rate considerably. The proposed circuit uses source switching and current mirror topology to increase on/off speed of power MOSFET to achieve nanosecond current pulse. It reduces parasitic inductance effect and also overcomes the bandwidth limitation of conventional pulse current driver. Experiments show the proposed circuit provides 390mA current pulse with 40nswidth.