Verify VIN is off/disabled and no voltage is applied to the UUT.

Connect oscilloscope probes to VIN (20 V/DIV), VDD (4 V/DIV), and COMP (2 V/DIV).

Connect the differential probe to VO and ISO_GND at low range, 1/20 (scaled to 4 V/DIV).

Set the oscilloscope to single-trigger on VIN rising at 25 V. Set a time base of 50 ms/DIV.

Verify that the load is set to 0.25 A and is still enabled.

Turn on the VIN supply at 50 V. The oscilloscope should trigger and produce the waveforms shown in figure 5-6. If your result is the same as figure 5-6 then your EVM is functioning correctly, thus far. If your result does not resemble figure 5-6 then stop. Troubleshoot the EVM at 50 VIN. Do not increase VIN until after troubleshooting.

When VIN is 50 V only and with 0.25 A load, verify the following DC measurements at the test points:

1. VOUT+ (yellow TP) to ISO_GND ≈ 16.4 Vdc

2. V_AUX (white TP) to GND ≈ 18.7 Vdc

3. VDD (white TP) to GND ≈ 18.6 Vdc

4. VREF (white TP) to GND = 5.0 Vdc

5. FB (white TP) to GND = 2.5 Vdc

Turn off the VIN supply.

Increase VIN to 400 V with 1.3 A load and repeat steps 4 to 8. Verify that VOUT is OK at this condition.

Turn off the VIN supply.

Increase VIN to 800 V. At 800 V and 0.25 A load [and 2.7 A load] your result should be similar to figure 5-7 [and figure 5-8]. If your results are the same as figure 5-7 and 5-8 at 800 V then your EVM is 100% functioning correctly and you can proceed with other tests.