LED typical thyristor dimming design case based on LinkSwitch-PL

The LinkSwitch-PL family of highly integrated single-chip off-line switch ICs is suitable for LED lighting applications and can be designed with single-stage isolated (or non-isolated) constant current output drivers with power factor correction. The non-isolated design is compatible with low-cost TRIAC dimmers and offers a 300:1 dimming range. The low component count easily accommodates the space-constrained requirements of LED replacement lamp designs (eg, A19 and candle light sizes), while the 0.9 PF, low THD value, and harmonic input current allow a single driver design to be used worldwide.

This guide is designed to help engineers design isolated or non-isolated AC-DC power supplies that provide constant current drive for LED loads. This application note provides detailed instructions on how to use PIXls design tables for PIExpertTM software, how to select key components, and how to optimize your design (especially for TRIAC dimmers). LinkSwitch-PL is suitable for both flyback and buck-boost topologies, but this document only covers flyback topologies.

Support for how to use the PIXls design spreadsheet for boost-buck topology design has been planned and will be provided in a separate guide. In addition to this guide, readers will find the Reference Design Kit (RDK) very useful. Full-featured engineering prototypes, engineering reports, and device samples are included in each kit.

Basic circuit structure

The figure above is a typical application circuit diagram of a thyristor dimming, non-isolated LED driver. Circuit functional blocks that require interfacing with thyristor phase angle dimmers are labeled PassiveDamper, AcTIve Damper, and Bleeder, which can be used for non-dimming applications. Remove.