Test Procedure for NCL30000LED2GEVB 230 Vac Dimmable LED Driver Evaluation Board 19 April 2010 Introduction: The NCL30000LED2GEVB 230V Dimmable Evaluation Board is a 180 – 265Vac input, isolated high power factor single-stage off-line power supply intended to provide a constant current output for powering high brightness LEDs. This circuit is optimized for leading (Triac) phase-control dimmer operation. The output has over current, over temperature, and open load protection. The evaluation board is configured to provide a nominal current of 350 mA with an open LED clamp voltage of ~56V. The switching topology is a critical conduction mode (CrM) flyback converter. Test Equipment Required: 1. Adjustable, isolated AC power source capable of zero to 265 Vac output at up to 500mA. AC source should have the capability of measuring delivered power in watts and power factor. If not, an AC line analyzer or AC wattmeter should be used. 2. Digital volt/amp meters to measure output current and voltage to the electronic load. 3. A variable electronic load or rheostat capable of up to 20 watts and at least 60 volts. If an electronic load is used it must have a constant resistance mode. 4. Oscilloscope with probe to monitor output ripple on the demo converter. Setup Procedure: Set the equipment as shown in the diagram on the next page so the input and output voltage and current of the evaluation board can be measured. The oscilloscope should be set up so that the output ripple can be monitored. Page 1 of 3 4/19/2010 Test Procedure for NCL30000LED2GEVB 230 Vac Dimmable LED Driver Evaluation Board AC Source volts 115 Vac DVM - + AC out Vadj Iadj O'scope Board Under Test WATTS (Required if not in AC source) AC in + DC out Electronic Load amps + DVM - + Adj Test Procedure: 1. Connect UUT (Unit Under Test) to the test setup. Switch the electronic load on, set to constant resistance mode and the load adjust to high resistance/zero load; switch all of the digital meters on (assuming they are wired properly for voltage and current sensing); turn the oscilloscope on with sensing in AC mode and 200 mV per division vertical and a sweep rate of 5 mS per division. Connect the scope probe to the demo board’s output terminals. 2. With the AC source OFF, set the current limit on the AC source to 500 mA and the output voltage to 230 Vac. 3. Turn on the AC source. At no load, the power supply demo board output voltage should be between 54 and 58 volts on the DVM. 4. Adjust the electronic load from no load slowly up until the output voltage reduces to between 36.5 and 37.5 volts. The output current should be within the range of 332 to 368 mA. Record the measured load current for future reference. Input power should be less than 16.8 watts. Figure 1 shows a typical voltage/current regulation curve for this driver operating at 230 Vac input. The output ripple on the oscilloscope should be less than 1.5 V peak-to-peak including spikes. 5. Increase the load (reduce resistance) slowly and the current should remain constant within +/- 5 mA of the recorded value as voltage reduces with increased load (constant current output.) The current should be in range from 40 volts down to about 11 volts output. Adjust the electronic load back to 36.5 to 37.5 volts. 6. Reduce the AC input to 120 Vac and verify current reduces to between 170 and 230 mA. 7. Slowly increase the AC input to 265 Vac while monitoring output current. Current should steadily increase with line voltage and be within +/- 5 mA of the recorded value after dwelling a minimum of 1 second at any input voltage within the range of 230 to 265 Vac. 8. Turn the AC source off and disconnect UUT from test set. 9. Use a permanent marking pen to place a small ink dot on the white rectangles located on the PCB silkscreen. On the top side mark box “350” and on bottom side mark “230V”. Page 2 of 3 4/19/2010 Test Procedure for NCL30000LED2GEVB 230 Vac Dimmable LED Driver Evaluation Board End of Test. 60 50 LED Voltage (Vac) 40 30 20 10 0 0 100 200 300 400 500 600 LED Current (mA) Figure 1 – Typical Current Transfer Function Page 3 of 3 4/19/2010