AN4376 datasheet(26/37 Pages) STMICROELECTRONICS

Part #	AN4376

Description	10 W wide range non-isolated high power factor LED driver using HVLED815PF

PDF	37 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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PFC waveforms

AN4376

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DocID025380 Rev 1

7.4

Controller startup and light-ON

With a VCC capacitor of 22

F (see Figure 9: EVLHVLED815W10A demonstration board

schematic on page 12), the HVLED815PF turns-on in 50 ms. A light appears hundreds

milliseconds later (see CH1-LED current).

A capacitor C5 (2.2 µF) on the ILED pin is charging during the start-up phase and it is

responsible of the LED current soft-start time.

Acting on this C5 capacitor, it is possible to modify the soft-start time. In detail, to speed up

the loop it is enough to reduce the C5 capacitor reducing the soft-start time.

Figure 30. ILED pin operation at 230 VAC

Figure 31. ILED pin operation at 265 VAC

CH1: VIN

CH2: BJT-base

CH3: ILED pin

CH4: C5 capacitor

CH1: VIN

CH2: BJT-base

CH3: ILED pin

CH4: C5 capacitor

Figure 32. Startup at 100 VAC - 50 Hz

Figure 33. Startup at 230 VAC - 50 Hz

CH1: LED current

CH2: CS

CH3: VOUT

CH4: VCC

CH1: LED current

CH2: CS

CH3: VOUT

CH4: VCC

AN4376 Datasheet(PDF) 26 Page - STMicroelectronics