Power Integrations, a company manufacturing LED driver ICs for general lighting applications, has released a 25 W LED lighting reference design suitable for T8 tubes.
link switch PH application schematic
The design example report (DER-287) covers a reference design that has a high efficiency of more than 91% , harmonic distortion standard EN61000-3-2 Class C, and a PF factor of more than 0.9, thereby satisfying the commercial standards. The design DER-287 is of a single stage converter which has been created based on LNK 409EG belonging to the family of LED driver ICs, namely LinkSwitch-PH. The single-stage technology eliminates opto-isolators and aluminium electrolytic input bulk capacitors used in traditional two-stage solutions, thereby increasing the lifetime of the product.
Andrew Smith, product manager, Power Integrations, stated that the importance of achieving improved power-conversion capacity is as critical as choosing LEDs for maximising the illuminating capacity of a lighting fixture. It is highly challenging to achieve efficiencies more than 88% economically in a T8 tube form factor. However, it is possible to achieve efficiencies greater than 91% if a single-stage topology is implemented. The designs used in commercial and industrial applications require high PF or low TDH, a standard incorporated in LinkSwitch-PH LED driver IC, making it suitable for world-wide usage. The LinkSwitch-PH family characterises an integrated monolithic design that includes driver, controller and switching MOSFET into one package. The series also incorporates numerous protection characteristics like over-current and over temperature protection. This implies that a minimal number of external components are needed to implement the product, which is a critical consideration in compact T8 tube enclosures.