Test Procedure
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6
Test Procedure
All tests will use the set up described in
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.
6.1
Applying Power to the EVM
1.
2.
3.
4.
Set up the EVM as described in
of this user guide.
Ensure the AC source is off.
Ensure potentiometer R26 is rotated completely clockwise.
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.
6.2
Line/Load Regulation and Efficiency Measurement Procedure
1.
2.
3.
4.
5.
6.
7.
8.
Apply power to the EVM per
Vary the constant voltage load from 110 V to 55 V.
Observe output current on A1 stays constant.
Vary AC source from 90 VRMS to 264 VRMS.
Observe output current on A1 stays constant.
PFC inductor ripple current can be measured at CL1 using an oscilloscope and current probe.
The buck output inductor current can be measured at CL2 using an oscilloscope and current probe.
See
for some typical test results.
6.3
PFC Disable
1.
2.
3.
4.
5.
6.
7.
Ensure the AC source is off.
Connect a DC source to J2.
Set DC source to 0 V.
Apply power to the EVM per
Increase DC source to 3.3 V. This input can accept up to 12 V.
Observe PFC output voltage reduces, V2.
PFC inductor ripple current looses high frequency component.
8
A 0.9-A Constant Current Supply with PFC for 100-W LED Lighting Applications
SLUU355A – March 2009 – Revised June 2009
TI [ TEXAS INSTRUMENTS ]
