List of figures

AN2459 - Application note

4/35

List of figures

Figure 1.

Digital ballast scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2.

PFC Transition Mode principle (frequency is not to scale) . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 3.

Principle of the Enhanced One Pulse Mode, inside the ST7Lite1B . . . . . . . . . . . . . . . . . . . 7

Figure 4.

Input voltage & current with modified EMI filter

(compared to STEVAL-ILB002V1) PF = 0.994 THD = 10.3% . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 5.

Input voltage & current measured on STEVAL-ILB002V1 (old EMI filter)

PF = 0.991 THD = 10.4% . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 6.

Schematics of STEVAL-ILB002V1 reference design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 7.

Modified EMI filter (not included in STEVAL-ILB002V1 reference design . . . . . . . . . . . . . 11

Figure 8.

General flowchart of PFC software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 9.

Input voltage sensing circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 10.

Input voltage sensing circuit output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 11.

The mains turn-on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 12.

Output voltage sensing circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 13.

Output voltage control loop flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 14.

Application start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 15.

Lamp restart - behavior of the control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 16.

Zero current crossing detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 17.

PFC MOSFET overcurrent detection circuit and zero coil current detection circuit with

indicated testing connection and microcontroller inner structure . . . . . . . . . . . . . . . . . . . . 24

Figure 18.

Maximum MOSFET's TON protection routine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 19.

Overcurrent reaction demonstration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25