AN993 datasheet(23/27 Pages) STMICROELECTRONICS

No de pièce	AN993

Description	Electronic ballast with PFC using L6574 and L6561

PDF	27 Pages

Scroll/Zoom	100%

Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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23 / 27 page

AN993

Design tips

Doc ID 5656 Rev 10

23/27

If one of these conditions is not verified, the evaluation process has to be redone changing

the initial hypothesis (frequencies or assumption on the Cb ripple). If everything concords,

the values found can be used and a preliminary stage of design can be concluded. Further

experiments may be required and the initial assumptions may need to be verified to correctly

set the components and frequency values, and if necessary another evaluation process

reiterated with better assumptions.

The following flow chart can help the iteration process.

Figure 21.

Operating transfer function

Figure 22.

Iterative process

AM01329v1

f = f(L,C,rr)

fmin

Vlamp

Vin

freq

AM01330v1

L evaluation

C evaluation

DATA:

operating lamp elec.characteristic

HVB

HYPOTHESIS:

fmin

HYPOTHESIS:

fpre

DATA:

ignition and preheating lamp elec.characteristic

Transfer preheating funct.

Transfer operating funct.

check on board

AN993 Fiches technique(PDF) 23 Page - STMicroelectronics