ST AN3424 Application note

AN3424

Application note

STEVAL-ILL042V1: high power factor flyback LED driver based on the L6562A and TSM101

Introduction

The high-PF flyback configuration, used to drive a new design of the 60 W LED array, is based on the L6562A and the TSM101 controller (Figure 1).

This configuration uses an isolated feedback with an optocoupler and a secondary side reference/error amplifier, the TSM101, for voltage and current regulation.

The TSM101 includes two op amps: one op amp is used for constant voltage control

and the other for constant current control. A precise internal current generator, available, can be used to offset the intervention threshold of the constant current regulation.

The L6562A is a PFC controller operating in transition-mode. The highly linear multiplier includes a special circuit, able to reduce AC input current distortion, that allows wide-range- mains operation with an extremely low THD, even over a large load range.

The TSM101 compares the DC voltage and current level of a switching power supply to an internal reference. It provides a feedback through an optocoupler to the L6562A controller in the primary side.

This system, designed by using the L6562A and the TSM101 controller, offers more advantages in terms of output current and voltage stability.

The input capacitance is so small here that the input voltage is very close to a rectified sinewave. Besides, the control loop has a narrow bandwidth so as to be little sensitive to the twice-mains frequency ripple appearing at the output.

Efficiency is high at heavy load, more than 90% is achievable: TM operation ensures slow turn-on losses in the MOSFET and the high PF reduces dissipation in the bridge rectifier.

The output voltage exhibits a considerable twice-mains frequency ripple, unavoidable if a high PF is desired. Speeding up the control loop may lead to a compromise between a reasonably low output ripple and a reasonably high PF. To keep the ripple low, a large output capacitance (in the thousand F) is anyway required.

Figure 1. Board image

November 2011

Doc ID 018991 Rev 1

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Contents	AN3424

Contents

1	Board block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. 4
2	Electrical schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . .	. 5
3	Design and calculation parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8
4	Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	18
5	EMC tests results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	19
6	Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	20
7	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	21

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AN3424	List of figures

List of figures

Figure 1. Board image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Figure 2. 60 W LED driver block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 3. Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Figure 4. High-PF flyback characteristic functions: F1(x) diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 5. High-PF flyback characteristic functions: F2(x) diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 6. Flyback characteristic functions: F3(x) diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Figure 7. 60 W high-PF with L6562 and TSM101: electrical schematic. . . . . . . . . . . . . . . . . . . . . . . 13 Figure 8. Pin vs. Vin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 9. THD vs. Vin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 10. PF vs. Vin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 11. Efficiency vs. Vin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 12. Startup @ 230 V L6562A Vcc (red) MOSFET drain voltage (brown) . . . . . . . . . . . . . . . . . 15 Figure 13. Startup 230 V - Iout (green), Vout (blue), L6562A Vcc (red) . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 14. Vin, Iin. PFC @ 185 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 15. Vin, Iin. PFC @ 230 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 16. Vin, Iin. PFC @ 265 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 17. Peak measure: line wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 18. Peak measure: neutral wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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Board block diagram	AN3424

1 Board block diagram

Figure 2 shows a block diagram of the system. The complete circuit is made up of two stages:

●The flyback converter which regulates the output voltage and performs the power factor correction.

●The current and voltage controller stage which regulates the current and voltage output feedback.

This topology, thanks to STMicroelectronics ICs L6265A and TSM101, realizes a high-PF flyback converter with voltage and current output regulation.

Figure 2. 60 W LED driver block diagram

Filter

Mains +

Bridge

LED

L6562A

TSM101

AM10530v1

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2

AN3424

L3

and schematic Electrical

F1

2x47mH, 1.5A

J3

2

2A 1000V

C16

C26

3

FUSE 1A

2

3

2

C1A

C1B

-

BR1

+ 1

2.2n-Y1- 250V

2.2n-Y1- 250V

Vin=185 to 265 Vac

1

4

100nF X2 Cap

100nF X2 Cap

CON3

1

4

C20

3

2200nF630VDC

T1

5

TRAFO

D5

C21

13

4

C9

Vout=130 Vac, Iout=0.462A

D6

STTH2L06

C10

C24

1

1n-Y1- 250V

1.5KE350A

3

330uF, 160V

330uF, 160V

C13

12

330uF, 160V

2

2

D1

100 nF

J1

STTH1L06

R14

CON2

12 kOhm

R30

D4

Q1

R4

D3

10

1 MOhm

TMMBAT46

6

STP7N95K3

10 Ohm

TMMBAT46

C15

C18

R32

47uF, 35V

100 nF, 50V

7

9

R33

68 kOhm

R29

R35

12 kOhm

1 MOhm

10 Ohm

R19

68 kOhm

R26

R22

R16

82 kOhm

R44

R25

12 kOhm

1 MOhm

R37

1.1Ohm 0.25W

1.1Ohm 0.25W

R21

C14

R34

R5

20 kOhm

100 kOhm

68 kOhm

C22

R27

0 Ohm

1nF 25V

4.7 uF

160V

018991DocID

8.2 kOhm

C17

schematicElectricalFigure3.

2.2nF

D9

4

GND MULT 3

2

VCC INV 1

R31

18V 0.5W

R15

R18

ZCD CS

GD COMP

100 kOhm

100 Ohm

U3

R36

15 kOhm

L6562AT

680k

R28

100 kOhm

1Rev

5

6

7

8

OPTO ISOLATOR-A

bill

C23

150 pF 25V

ISO1

1

4

C28

schematic Electrical

3

2

material of

C19

R38

1uF 50V

R23

1uF

10KOhm

30 kOhm

R41

10 kOhm

4

3

7 2

8 1

C25

R24

Gnd

Vrin Csense

100 nF 25V

R42

U5

2.2kOhm

TSM101

2 kOhm

Crin

5

6

C27

1uF 50V

R20

OutputCrref

VCCVref

47kOhm

C29

and

1uF 50V

D7

R39

bill

18 Ohm

R17

TMMBAT46

D8

1.5 kOhm

TMMBAT46

R40

of

1v13AM105

1.2 Ohm, 1%

material

R43

1.2 Ohm, 1%

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Electrical schematic and bill of material						AN3424
Table 1.	Bill of material
Reference		Value		Rated	Type	Manufacturer
BR1				2 A/1000 V
C1A, C1B		100 nF		275 Vac	Polypropylene film
					capacitor X2
C9, C10, C24		330 µF		160 Vdc	Electrolytic capacitor
C13		100 nF		250 Vdc	Polyester
					capacitor
C14		1 nF		25 Vdc	COG ceramic
					capacitor
C15		47 µF		35 Vdc	Electrolytic capacitor
C16, C26		2.2 nF		250 Vac	Y1 capacitor
C17		2.2 nF			X7R ceramic
					capacitor
C18		100 nF		50 Vdc	X7R ceramic
					capacitor
C19, R38		220 nF, 100 kΩ
C20		220 nF		630 Vdc	Polypropylene film
					capacitor
C21		1 nF		250 Vac	Y1 capacitor
C22		4.7 µF		160 Vdc	Electrolytic capacitor
C23		150 pF		25 V	Capacitor
C25		100 nF		25 Vdc	X7R ceramic
					capacitor
C27, C29		1 µF		50 Vdc	Ceramic capacitor
C28		10 nF		50 Vdc	X7R ceramic
					capacitor
D1		STTH1R06		1 A/600 V	Ultrafast diode	STMicroelectronics
D3, D4		TMMBAT 46		100 V		STMicroelectronics
D5		STTH2L06		2 A/600 V	Ultrafast diode	STMicroelectronics
D6		1.5KE350A		350 V/1.5 kW	Transil	STMicroelectronics
D7, D8		TMMBAT 46		150 mA/100 V		STMicroelectronics
D9				18 V/0.5 W	Zener diode
F1				1 A/250 V	Fuse
ISO1		PC817			OPTO
					ISOLATOR-A
J1		CON2
J3		CON3
L3		2 x 47 mH		1.1 A	Common mode
					choke

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AN3424				Electrical schematic and bill of material
Table 1.	Bill of material (continued)
Reference		Value	Rated		Type	Manufacturer
	Q1	STP7N95K3	950 V/1.1 Ω		SuperMESH™III	STMicroelectronics
R4, R35		10 Ω	0.25 W
R5, R19, R32		68 kΩ	0.25 W, 1%
R14, R16, R33		12 kΩ	0.25 W
	R15	100 Ω	0.25 W
	R17	1.5 kΩ	0.25 W
	R18	15 kΩ	0.25 W
	R20	47 kΩ	0.25 W
	R22	82 kΩ
	R23	30 kΩ
	R24	2.2 kΩ	1%
R25, R44		1.1 Ω	0.25 W, 1%		Metal film resistor
R26, R29, R30		1 MΩ	0.25 W, 1%
	R27	8.2 kΩ	0.25 W, 1%
R28, R31, R34		100 kΩ	0.25 W
	R36	680 kΩ	0.25 W, 1%
	R37	20 kΩ	0.25 W
	R39	18 Ω	0.25 W
R40, R43		1.2 Ω	0.25 W, 1%		Metal film resistor
	R41	10 kΩ	1%
	R42	2 kΩ	1%
	T1	TRAFO	0.9 mH
	U3	L6562A			TM, PFC controller	STMicroelectronics
	U5	TSM101			Voltage and current	STMicroelectronics
					controller

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