AN3410

Waveforms

Doc ID 018890 Rev 1

17/28

6

Waveforms

Trace colors:

–

Yellow = line voltage, 50 V/div ref 0

–

Magenta = line current, 100 mA/div ref 0

–

Blue = LED voltage, 10 V/div ref -3 div

–

Green = LED current, 100 mA/div ref -3 div

Note that the flat spot near the zero crossing becomes longer as the load voltage becomes

a larger percentage of the line voltage (low line is worst). This will place an upper limit on the

LED output voltage as waveform distortion reduces power factor. The design can be pushed

to higher numbers of LEDs, up to the point where power factor or THD become limiting

factors.

Figure 12.

Waveforms at 96 V line

Figure 13.

Waveforms at 108 V line

Figure 14.

Waveforms at 120 V line

Figure 15.

Waveforms at 132 V line