AN4496 datasheet(9/18 Pages) STMICROELECTRONICS

部件名	AN4496

功能描述	How to get a high power factor with the HVLED815PF device

PDF	18 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

9 / 18 page

DocID026370 Rev 1

9/18

AN4496

ILED pin

Equation 16

Where VINthL is the lower transition voltage and Rr3 << (1 + hFE_Qr) * Rpe.

Figure 8. Equivalent pin ILED modulation circuitry in high input voltage range

The higher transition voltage (VINthL ) is determined by Rpe but the base of Qr is always

biased while the collector voltage drops near to zero and modelling is not simple.

Starting from the below estimated values and the recommended value in Section 2.10 on

page 16 further fine tuning of the final application can be done assuming that:



Decreasing/increasing the Dz Zener voltage the lower transition voltage

decreases/increases



Decreasing/increasing the Rr3 resistor value the lower and the higher transition voltage

increase/decrease



Decreasing/increasing the Rr1, Rr2 resistor value the lower and the higher transition

voltage decrease/increase



Decreasing/increasing the Rpe resistor value the spread between the lower and the

higher transition voltage decreases/increases.

AN4496 数据表(PDF) 9 Page - STMicroelectronics