Power Integrations (San Jose, CA) recently 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 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 20W (85V at 240mA) at an efficiency as high as 92% (DER-337) and 89% (DER-345).
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