AN2811

Test results and waveforms

Doc ID 14904 Rev 1

19/25

The load can be open-circuit (LED absent or wrong polarity at installation) or short-circuit

due to the system undergoing installation or an operating anomaly. The LED lamp can be

damaged due to overtemperature, for example. The system should be able to withstand

damage until removal of the anomaly, thanks to the VIPer17 which provides full protection

against output short-circuit as well as output open-circuit. In Figure 30 and Figure 31 the

waveform from the short-circuit load condition is captured at the highest AC line input 264 V,

which is the most hazardous condition to the system board. In Figure 32 and Figure 33 the

waveforms are captured at the highest AC line input 264 V with the output load in open-

circuit condition.

Figure 30.

Vdd and Vds at 264 VAC, output in

short-circuit

Figure 31.

Io at 264 VAC, output in short-

circuit

Top trace: Vdd (10 V/div)

Bottom trace: Vds (100 V/div)

Time: 100 ms/div

Io: 200 mA/div

Time: 100 ms/div