EVL6591-90WADP STMicroelectronics

AN2852 Application note EVL6591-90WADP: 90 W AC-DC asymmetrical half-bridge adapter using L6591 and L6563 Introduction This document describes the characteristics and performance of a 90 W wide range input AC-DC adapter based on asymmetrical half-bridge topology (AHB). The converter comprises a two-stage approach: a PFC front-end stage using the L6563 TM PFC controller and a DC-DC stage that implements the asymmetrical half-bridge (AHB) topology driven by the L6591, the new PWM controller dedicated to this architecture. Thanks to the AHB topology, the system offers good electrical performance (EPA 2.0 compliant) with a low-voltage and high-current output (12 V - 7.5 A). The order code for this demonstration board is EVL6591-90WADP. Figure 1. EVL6591-90WADP demonstration board AM01816v1 January 2009 Rev 1 1/35 www.st.comContents AN2852 Contents 1 Main characteristics and circuit description . 4 2 Operating waveforms 7 2.1 Asymmetrical half-bridge (AHB) typical waveforms 7 2.2 Low-load operation 10 2.3 Short-circuit protection . 12 2.4 Overvoltage protection . 13 2.5 Startup sequence . 15 3 Electrical performance 17 3.1 Efficiency measurement and no-load consumption . 17 3.2 Harmonic content measurement . 20 4 Thermal measurements . 22 5 Conducted noise measurements (pre-compliance test) . 24 6 Bill of material . 25 7 PFC coil specifications 29 7.1 Electrical characteristics 29 7.2 Mechanical aspect and pin numbering . 30 8 AHB transformer specifications 31 8.1 Electrical characteristics 31 8.2 Mechanical aspect and pin numbering . 32 9 PCB layout 33 10 Revision history . 34 2/35