AN4346 datasheet(27/33 Pages) STMICROELECTRONICS

Part #	AN4346

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

PDF	33 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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27 / 33 page

DocID025107 Rev 1

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AN4346

Electrical waveform

3.4

Startup

With a VCC capacitor of 47 F, the HVLED815PF device turns-on in 100 ms (see Figure 37

and Figure 38). Light appears hundreds milliseconds later.

A capacitor C5 (4.7

F) 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 35. ILED pin operation at 230 Vac

Figure 36. 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 37. Startup at 100 Vac - 50 Hz

Figure 38. Startup at 230 Vac - 50 Hz

CH1: LED current

CH2: CS pin

CH3: VOUT

CH4: VCC pin

CH1: LED current

CH2: CS pin

CH3: VOUT

CH4: VCC pin

AN4346 Datasheet(PDF) 27 Page - STMicroelectronics