AN2961 Datasheet, PDF (8/14 Pages) STMicroelectronics – STEVAL-ILL026V1 non-isolated 3 W offline LED driver based on the VIPER22A-E

Test results
5
Test results
AN2961
VIPER22A-E startup
As shown in Figure 3 below, the internal current generator of the device charges the
capacitor connected at the pin. When the voltage across this capacitor reaches the
VIPER22A-E turn-on threshold, the system starts.
Figure 3. VIPER22A-E startup
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F2 - LED current (magenta waveform), F3 - VIPER22A-E voltage (cyan waveform).
Steady state
In Figure 4, the LED current and voltage are shown.
Figure 4. 110 V steady state operation
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F2 LED current (magenta waveform), F3 LED voltage (blue waveform).
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Doc ID 15559 Rev 1
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