High-performance LED driver power supply design

With the heavy use of high-power LED light source, the technical requirements for LED drivers are increasing. High-voltage high-power LED driver can be connected directly to the grid (85V-265V). Can provide 100W of power. These drivers usually provide high current and high voltage output and have high efficiency. At the same time provide a variety of protection to improve the reliability of the drive.

Based on AX6066 + A433LED driver circuit design

The AX6066 is a converter with primary feedback from 12 watts to 65 watts. The AX6066 is suitable for AC / DC power applications to meet the application requirements of AC lines requiring low power consumption and high average efficiency without load. The chip can control the converter to work in discontinuous mode. Discontinuous operation provides a unique safety current limit function that is also insensitive to signal jitter on the AC line. Peak current modulation mode does not require slope compensation.

The AX6066 works by driving the source of an external high-voltage power tube. This structure is called common base, common emitter (source) drive. It highlights two major benefits of quick start up and ensuring that the control chip is not connected to high voltage under unloaded conditions. The normal operation of the converter with feedback flyback structure has no effect.

The feedback pin accepts current rather than voltage. Under no-load operation, this design minimizes the power consumption of the primary side by avoiding the energy consumption of the external resistor from current to voltage.

With constant peak current and varying off-time modulation, the AX6066 has the highest average efficiency between peak power and 22% peak power. The AX6066 internal modulation tends to keep its power constant between 22% and 100% of peak load, eliminating design challenges and bringing the converter's average efficiency to an energy star rating.

Total base, total emitter bias and start

The AX6066 uses a common-base, common-emitter drive and bias to control the high-voltage power tube and provides an initial bias when activated. The common-base, common-emitter structure achieves a universal gating through low-voltage control of the switch connected between the ground and the source of the high-voltage power transistor. The following key points need attention:

1. External high-voltage power tube to be added to the DC voltage gate.

2. External high-voltage power transistor is driven by the source, rather than the gate.

3. The initial coil of the entire current through the internal low-voltage drive tube.

The AX6066 integrates 90mΩ low-voltage switching field-effect transistors with all associated current sense and drive. The external high-voltage power tube is forced to follow the internal fast low-voltage driver tube. The drain and gate of the external high voltage driver tube do not affect the turn-off speed because the gate terminal is connected to a separate DC source. The common-base, common-emitter structure allows external high-voltage power MOSFETs to be quickly turned off and the switching losses of field-effect transistor switches reduced.