Reference design for PAR38 LED spotlight
Fig. 1: The populated DER-350 circuit board assembled
Fig. 2: The populated DER-350 board is placed inside the CREE PAR38 lamp
The 20W reference design includes an isolated, high-power-factor, TRIAC-dimmable LED driver optimized to deliver an LED current of 550 mA at 36 V (nominal) from an input voltage range of 90 VAC to 132 VAC. The combined PFC (>0.98) and CC single-stage, isolated topology of the LYTSwitchTM-4 IC delivers excellent efficiency, and low component count. Over-voltage, overcurrent and over-temperature protection features are built-in.
The following brief outline of this extensive reference design will give a taste of how complete and robust this design is:
Schematic
Fig. 3: Schematic of DER-350. For better resolution click here.
DER-350 also showcases the LYTSwitchTM-4 IC’s excellent TRIAC dimming with very fast sub-200 ms start-up, reduced pop-on and no dead-travel, easily satisfying NEMA dimming curve requirements, for both leading-edge and trailing-edge dimmers.
Fig. 4: Transformer build diagram
Transformer spec
The reference design outlines the electrical specs and materials for the transformer. In addition, a transformer build diagram is included with construction details. Finally, a detailed transformer design spreadsheet is shown.
L1 Inductor spec
Fig. 5: L1 inductor electrical diagram
An electrical diagram is shown for the L1 inductor along with electrical specs and materials. A build diagram and inductor construction details are also included.
U1 Heat sink
Fig. 6: U1 heat sink
Performance data
A full work-up of actual performance test data including efficiency graph, line/load regulation graph, power factor graph, A-THD graph, harmonic currents bar graph with 11, 12 and 13 LED loads. Test charts include data for 11, 12 and 13 LED loads; Current harmonics limits for IEC61000-3-2 for 11, 12 and 13 LED loads—all passing.
Dimming performance data is shown graphically.
Fast Start-up of less than 200 ms with TRIAC-based dimmer is shown in graphs.
Pop-on point with TRIAC-based dimmer is graphically shown.
Output and input current waveforms with dimmer are shown as well.
Dimmer compatibility
A full US list of 71 Lutron, Cooper and Leviton dimmer part numbers are outlined
Thermal Performance
Fig. 7: Thermal test set-up
Full sets of thermal measurements were done and recorded with a PAR38 lamp
Conducted EMI
Conducted EMI tests proved well below the maximum limits in EN55015 B
Fig. 8: EMI Test Set-up with the unit and LED load placed inside a conical metal housing as described in CISPR 15 / IEC: 2005 standard.
The unit was subjected to ±2500 V 100 kHz ring wave and ±500 V differential surge at
120 VAC using 10 strikes at each condition. A test failure was defined as a non-recoverable
interruption of output requiring supply repair or recycling of input voltage.
The unit tested passed both ±2500 V 100 kHz ring wave and ±500 V differential surge with and without MOV.
For more information please go the Power Integrations website.
This article originally appeared on EDN
If you enjoyed this article, you will like the following ones: don't miss them by subscribing to :
