 White LEDs are gaining popularity as sources of illumination because of their high efficiency and reliability.
The typical forward voltage drop of a white LED is approximately 3.5 V. When these LEDs are powered from a single- or two-cell battery, a boost converter is needed to boost the voltage to drive the LEDs.
This evaluation board, based on the L6920D, implements a high-efficiency step-up converter that requires only a very few passive components to convert the battery voltage to the selected output voltage or current. Start-up is guaranteed at 1 V, and the device operates down to 0.6 V. The device has a very low quiescent current of only 10 μA.
An internal synchronous rectifier is used with a 120 mΩ P-channel MOSFET, replacing the conventional boost diode, to improve the efficiency.
This also reduces cost in the application since no external diode is required. |
