AN4129 datasheet(25/39 Pages) STMICROELECTRONICS

Part #	AN4129

Description	STEVAL-ILL044V1: 9 W Triac dimmable, high power factor

PDF	39 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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25 / 39 page

AN4129

Circuit description and design guidance

Doc ID 023314 Rev 1

25/39

Figure 30.

Conducted EMI limits

We design for peak noise at the FCC limit at 150 kHz. The design leaves some margin due

to the frequency selection. Peak-to-peak of the 2 mVrms limit is about 6 mV per line relative

to ground.

The input filter is shown below.

Figure 31.

Input EMI filter

The typical differential filter consists of 4 components. Starting at the noise source these

are:

●

Shunt capacitor on the converter input (C1)

●

Series inductor L1 and L2 in series, or differential (leakage) inductance of a common

mode choke

●

Shunt capacitor across line (C2)

●

Line impedance (in the LISN, about 100

Ω line-to-line, 50 Ω line-to-ground at

measurement frequencies).

4.12.1

Supporting the flyback input current

First we consider the differential current drawn by the converter. The input current waveform

at line peak is sketched below:

AN4129 Datasheet(PDF) 25 Page - STMicroelectronics