A fully-integrated, 90% peak efficiency, 0.99 power factor, AC-DC LED Driver with on-chip direct-AC-connect series startup pre-regulator

In this paper, a fully-integrated AC-DC flyback converter for LED lighting applications is demonstrated. With the exception of passives, magnetics and rectification diodes, the entire AC-DC power converter including the ultra high voltage (UHV) power FET, control loop, current sensing, and startup functions have been integrated on the same monolithic bulk-CMOS silicon die. The startup function employs an 800 V depletion-mode pass device as part of a direct-AC-connect self-biased series pre-regulator. The entire AC-DC converter occupies an active area of 12.7 mm² on silicon, and has a peak efficiency of 90% for a 15 W LED load. A control loop architecture employing critical conduction mode (CrM) with line voltage feed-forward enables near-unity power factor performance.