AN4129 datasheet(30/39 Pages) STMICROELECTRONICS

Part #	AN4129

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

PDF	39 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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30 / 39 page

Circuit description and design guidance

AN4129

30/39

Doc ID 023314 Rev 1

The rather high current spike at the leading edge is due to the input capacitor charging thru

the fusible resistor. A small inductor may be added to soften this if space permits, but it does

no harm.

Even if Triac dimming is not required the damper should be used. The EMI filter can ring up

the supply voltage to very high levels at turn-on if it is not present, and instability has been

seen without the damper under normal operating conditions.

4.14

EMI plot

The conducted emissions plots for the two input lines are virtually identical. Only one is

shown below. The plot is the maximum of 10 scans for peak power.

Figure 39.

Conducted EMI, peak hold for 10 Scans

4.15

Startup

Figure 40.

Cold startup, input and LED currents

Where:

●

Yellow (not shown) = line voltage, triggers scope

●

Magenta = line current

●

Green = LED current.

AN4129 Datasheet(PDF) 30 Page - STMicroelectronics