New reference design for 5W offline LED driver
Power Integrations
RDK-251
Power Integrations has announced a new reference design (RDK-251) for a 5W offline LED driver that includes flicker-free TRIAC dimming and single-stage power factor correction (PFC).
The reference design is based on Power Integrations' LNK457DG, part of the Linkswitch-PL range of LED driver ICs, which are optimised for compact, non-isolated installations.
The new reference design provides a single constant-current output of 350mA at a nominal LED string voltage of 15V.
The output current can be reduced using a standard AC mains TRIAC dimmer down to one per cent (3mA) without instability or flickering of the LED array.
The supply is compatible with both low-cost, leading-edge dimmers and more sophisticated trailing-edge dimmers.
It operates over the universal AC input range (85 to 265V AC, 47 to 63Hz) and can withstand an input range of 0 to 300V AC, improving field reliability and lifetime during line sags and swells.
Power factor is high (more than 0.9) and input current total harmonic distortion (THD) is low (less than 10 per cent at 115V AC and less than 15 per cent at 230V AC), meeting international requirements and enabling a single universal input design to be used worldwide.
The new reference design is suitable for compact form factors due to its component count of 38 passives and discretes (29 for non-dimming applications), in addition to the Linkswitch-PL device.
Manufacturability and longevity are also enhanced by the elimination of passive components required in older LED driver designs, including bulky and unreliable high-voltage electrolytic capacitors.
Linkswitch-PL, like its isolated counterpart Linkswitch-PH, incorporates the controller and high-voltage power MOSFET into a single silicon die, simplifying PCB layout by further minimising component count and eliminating parasitics between the controller and high-voltage power MOSFET.
The board fits inside a pear-shaped A19 LED replacement lamp with an E26/27 base.
RDK-251 contains full power-supply specifications, schematic, bill of materials, transformer documentation, printed circuit-board layout and performance data.
'This design enables SSL lamps with high-quality dimming, high power factor, low THD, small form factors and high reliability,' said Bill Weiss, lighting business development manager at Power Integrations.
'All regulatory requirements for energy efficiency are met or exceeded and solid-state lighting manufacturers can create one platform design that operates in both low-line and high-line installations,' he added.
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