Power Integrations announced two new reference designs describing high-efficiency, non-isolated, high-power-factor (PF) LED drivers for T8 tubes. The designs feature low component count and leverage simple magnetics and single-sided boards yielding industry-leading power densities of 14.2 W/in³. Based on the LNK460KG LED driver from Power Integrations’ LinkSwitch-PL family of ICs, the circuits detailed in DER-337 (high-line) and DER-345 (low-line) use single-stage non-isolated topologies which result in a profile of only 8 mm – small enough to be mounted behind the LEDs in the T8 tube.
The buck-boost (DER-337) or buck (DER-345) configurations deliver a power factor greater than 0.9 and low THD, meeting EN61000-3-2 C limits. The designs are EMI compliant, easily meeting the EN55015 (EMI) class B specification. The integrated single-stage driver IC controls both PFC and constant-current output resulting in a solution that uses fewer than 30 components. Both drivers deliver 20 W (85 V at 240 mA) at an efficiency as high as 92 % (DER-337) and 89 % (DER-345).
Download DER-337 at http://www.powerint.com/sites/default/files/PDFFiles/der337.pdf; DER-345 at http://www.powerint.com/sites/default/files/PDFFiles/der345.pdf. Each document contains the LED driver specification, schematic, PCB details, bill of materials, transformer documentation and detailed performance characteristics.