02/14/2014 2 www.onsemi.com
Test Procedure:
1. Switch the electronic load on and set to 10 mA 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 100 mV per division vertical and a sweep rate of 5 uS
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 400 mA and the
output voltage to 120 Vac.
3. Turn on the AC source and the power supply output voltage should be should be 12V +/-
0.50V, - 0.15V on the DVM.
4. Adjust the electronic load from no load slowly up to the full load rating of 1.75 amps.
The output voltage should remain within 120 mV (1%) of nominal if properly regulating.
The output ripple (switching frequency) on the oscilloscope should be less than 150 mV
peak-to-peak at full load. (Note – scope probe tip should be decoupled with a 0.1uF
ceramic capacitor and ground wire should not be used to get best accuracy and max
attenuation of switching noise pickup.)
5. Adjust the electronic load to 1.6 amps and the AC source down to 90 Vac and the power
supply output should still be in spec. Return the AC source to 120 Vac.
6. Set the output load to 75% of full load (1.31 amps), check the efficiency. Effic = (Vout x
Iout)/Pin. It should be greater than 76%.
7. Continue to increase the load slowly and the over-current protection should kick in about
an amp or less above the maximum current output rating. This should result in a “hick-
up” start-stop type of operation.
8. Set the load back to the rated max output current and the power supply should recover
with proper output voltage.
9. Adjust the electronic load to back to zero, switch the load off, and check the input power
(standby power). It should be below 75 mW.
10. Adjust the AC input to 230 Vac and repeat tests (3) through (8) with the exception of (5).
11. Switch the AC source off and disconnect the demo board.
End of Test.