AN2640 datasheet(8/36 Pages) STMICROELECTRONICS

Part #	AN2640

Description	Intelligent multipower digital ballast for fluorescent lamps

PDF	36 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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8 / 36 page

Half-bridge design criteria

AN2640

8/36

Half-bridge design criteria

The design of the half-bridge section involves dimensioning the resonant components:

ballast inductor and startup capacitor. The component design is not an easy matter and

several parameters must be considered, especially when different lamps must be driven

with the same resonant components. The main parameters to be considered are preheating

current and voltage, maximum preheating voltage, maximum ignition voltage and run lamp

voltage. For each lamp the transfer function was plotted in order to evaluate the operating

point in terms of preheating and run frequency. The resonant inductor has been chosen as

1.2 mH and the startup capacitor has been chosen as 10 nF.

Figure 4.

24 W lamp power

Figure 5.

39 W lamp power

AN2640 Datasheet(PDF) 8 Page - STMicroelectronics