6

Test Procedure

6.1

Applying Power to the EVM

6.2

Line/Load Regulation and Efficiency Measurement Procedure

6.3

PFC Disable

Test Procedure

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All tests will use the set up described in Section 5 of this user guide. Ensure potentiometer R26 is rotated

completely clockwise.

WARNING

HIGH VOLTAGE levels are present on this evaluation module

whenever it is energized. Proper precautions must be observed

whenever working with this module. There is an energy storage

capacitor (C17) on this module which must be discharged before

the board can be handled. Serious injury can occur if proper safety

procedures are not followed.

1. Set up the EVM as described in Section 5 of this user guide.

2. Ensure the AC source is off.

3. Ensure potentiometer R26 is rotated completely clockwise.

4. Set constant voltage load to between 55 V and 110 V. If using a HB-LED string ensure the voltage

drop, when operating, is between 55 V to 110 V nominal. Note the 1000-

µF/250 V capacitor is not

required on the output if using a HB-LED string.

5. Set AC source to 90 VRMS.

6. Turn on AC source.

7. Monitor PFC output voltage at TP4 and TP5, V2.

8. Monitor output current at A1.

9. Monitor output voltage at V1.

10. The EVM is now ready for testing.

1. Apply power to the EVM per Section 6.1.

2. Vary the constant voltage load from 110 V to 55 V.

3. Observe output current on A1 stays constant.

4. Vary AC source from 90 VRMS to 264 VRMS.

5. Observe output current on A1 stays constant.

6. PFC inductor ripple current can be measured at CL1 using an oscilloscope and current probe.

7. The buck output inductor current can be measured at CL2 using an oscilloscope and current probe.

8. See Section 7 for some typical test results.

1. Ensure the AC source is off.

2. Connect a DC source to J2.

3. Set DC source to 0 V.

4. Apply power to the EVM per Section 6.1.

5. Increase DC source to 3.3 V. This input can accept up to 12 V.

6. Observe PFC output voltage reduces, V2.

7. PFC inductor ripple current looses high frequency component.

A 0.9-A Constant Current Supply with PFC for 100-W LED Lighting Applications

8

SLUU355A – March 2009 – Revised June 2009

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