EVLVIP16L-4WFN STMicroelectronics

AN3028 Application note EVLVIP16L-4WFN: 16 V / 4.5 W, 60 kHz non-isolated flyback demonstration board using the VIPer16LN Introduction This document describes a 16 V - 280 mA power supply set in non-isolated flyback topology with the VIPer16LN, a new offline high-voltage converter by STMicroelectronics. The features of the device include an 800 V avalanche rugged power section, PWM operation at 60 kHz with frequency jittering for lower EMI, current limiting with adjustable setpoint, on-board soft-start, and safe auto-restart after a fault condition. Moreover, the VIPer16LN can work with or without the auxiliary winding. Operating with the auxiliary winding, it can attain very low standby consumption. Operating without the auxiliary winding, the IC is supplied by an internal current generator, thus saving the cost of the transformers auxiliary winding. Both possibilities are discussed in this application note. The protections available include a thermal shutdown with hysteresis, delayed overload protection, and open-loop failure protection (available only if the auxiliary winding is used). Figure 1. EVLVIP16L- 4WFN demonstration board August 2011 Doc ID 16135 Rev 1 1/37 www.st.comContents AN3028 Contents 1 Adapter features 6 2 Circuit description . 7 3 Transformer . 10 4 Testing the board 11 4.1 Typical waveforms 11 5 Line-load regulation and output voltage ripple 12 6 Burst mode and output voltage ripple 14 6.1 Efficiency . 15 6.2 Light-load performance 19 7 IC features 23 7.1 Soft-start 23 7.2 Overload protection . 23 8 Guidelines for feedback loop calculation . 25 8.1 Transfer function 25 8.2 Compensation procedure . 26 9 Thermal measurements . 28 10 EMI measurements . 29 11 Board layout . 30 12 Conclusions . 31 Appendix A Test equipment and measurement of efficiency and low-load performance32 A.1 Measuring input power . 32 2/37 Doc ID 16135 Rev 1