ST AN4007 Application note

AN4007

Application note

EVLVIP37LE5V3A: 15 W (5 V - 3 A) wide range single-output

demonstration board

By Fabio Cacciotto

Introduction

In several applications, such as LCD or plasma TVs, desktop computers, etc., the power
supply that converts the energy from the main, often includes two modules: the main power
supply that provides most of the power and is OFF when the application is OFF or in
standby mode, and the auxiliary power supply that provides energy only to some specific
parts of the equipment such as USB ports, remote receivers, or modems but is still ON
when the application is in standby mode.

It is often required that, in standby condition, the equipment input power is as low as
possible which means the input power of the auxiliary power supply in no load or light load
condition is reduced as low as possible.

This application note introduces a new offline high voltage converter from the VIPerPlus
family, the VIPER37LE and the presented demonstration board meets the specifications of a
wide range of auxiliary power supplies for said applications. Furthermore, it is optimized for
very low standby consumption, therefore helping to meet the most stringent energy saving
requirements.

Figure 1. Demonstration board image: power supply board

May 2012 Doc ID 022455 Rev 1 1/33

www.st.com

Contents AN4007

Contents

1 Test board: design and evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1 Output voltage characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Efficiency and light load measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.3 No-load consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.4 Light load consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.5 Typical board waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.6 Dynamic step load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.7 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2 Protection features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.1 Overload and short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.2 Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2.3 Secondary winding short-circuit and transformer saturation protection . . 23

2.4 Brownout protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3 Conducted noise measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4 Thermal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

6 Demonstration tools and documentation . . . . . . . . . . . . . . . . . . . . . . . 31

7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

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AN4007 List of figures

List of figures

Figure 1. Demonstration board image: power supply board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2. Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 3. Dimensional drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 4. Line and load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 5. Efficiency vs. output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 6. No load consumption vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 7. Light load consumption at different output power without brownout. . . . . . . . . . . . . . . . . . 10

Figure 8. Light load consumption at different output power with brownout . . . . . . . . . . . . . . . . . . . . 11

Figure 9. Drain current and voltage at full load 85 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 10. Drain current and voltage at full load 115 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 11. Drain current and voltage at full load 230 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 12. Drain current and voltage at full load 264 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 13. Output voltage ripple at full load and 230 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 14. Output voltage ripple at full load and 115 VAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 15. Output voltage ripple during burst mode and 115 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 16. Output voltage ripple during burst mode and 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 17. Dynamic step load: 0 to 50% load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 18. Dynamic step load: 50 to 100% load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 19. Dynamic step load: 0 to 100% load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 20. Soft-start feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 21. Overload event: OLP triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 22. Overload event: continuous overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 23. Overvoltage event: OVP triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 24. Overvoltage event: OVP triggering (magnification) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 25. 2nd level OCP: protection tripping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 26. 2nd level OCP: steady-state operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 27. Brownout protection: converter’s power-down phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 28. Brownout protection: converter’s wake-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 29. Brownout protection: converter’s wake-up (magnification) . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 30. CE average measurement at 115 VAC and full load: average measurement . . . . . . . . . . 27

Figure 31. CE average measurement at 230 VAC and full load: average measurement . . . . . . . . . . 28

Figure 32. CE average measurement at 115 VAC and full load: peak measurement . . . . . . . . . . . . . 28

Figure 33. CE average measurement at 230 VAC and full load: peak measurement . . . . . . . . . . . . . 29

Figure 34. Thermal map at 115 VAC and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 35. Thermal map at 230 VAC and full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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Test board: design and evaluation AN4007

1 Test board: design and evaluation

Ta bl e 1

bom list and
in

summarizes the electrical specifications of the power supply,

Figure 1

Ta bl e 3

and the PCB layout in

lists the transformer characteristics. The electrical schematic is shown

Figure 4

.

Ta bl e 2

provides the

Table 1. ALTAIR04-900 PLMS power supply: electrical specifications

Parameter Min. Typ. Max.

AC main input voltage 85 V

Mains frequency (fL) 50 Hz 60 Hz

Output voltage 4.75 V 5 V 5.25 V

Output current 3 A

Output ripple voltage 50 mV

Rated output power 15 W

Input power in standby 30 mW

Active mode efficiency 70%

Ambient operating temperature 60 °C

Table 2. VIPER37L demonstration board: bom list

Reference Part Description Note

AC

265 V

AC

R1 2.2 MΩ 1% tolerance

R2 3.9 MΩ 1% tolerance

R3 2 MΩ 1% tolerance

R4 150 kΩ 1% tolerance

R5 3.3 Ω

R6 330 Ω

R7 220 Ω

R8 12 kΩ

R9 120 kΩ 1% tolerance

R10 10 kΩ

R11 33 kΩ 1% tolerance

R12 39 kΩ 1% tolerance

R13 47 kΩ

R14 39 kΩ 1% tolerance

C1 220 pF - 630 V film capacitor

C2 33 µF - 400 V electrolytic

C3, C4 ZLK series 1200 µF - 16 V electrolytic Rubycon

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AN4007 Test board: design and evaluation

Table 2. VIPER37L demonstration board: bom list (continued)

Reference Part Description Note

C5 ZLH series 100 µF - 16 V electrolytic Rubycon

C6 B81133C1223M 22 nF - X2 EPCOS

C7 2.2 nF Y-CAP

C9, C10 10 nF ceramic – 25 V

C11 33 nF ceramic – 25 V

C12 22 µF - 35 V electrolytic

C13 2.2 nF ceramic – 25 V

C14 22 nF ceramic – 25 V

D1 1.5KE220A Transil™ ST

D2 STPS30L40CT Power Schottky diode ST

D3 STTH1L06A Ultra-fast high voltage diode ST

D5 BAT46RL Signal Schottky diode ST

D4, D7 1N4148 Signal diode NXP

D6 BZX79-C18 18 V Zener diode NXP

L1 ELC09D2R2F 2.2 H power inductor Panasonic

Note:

CM BU16-2530R7BL CM choke Coilcraft

BR DF08M-E3 Bridge diode Vishay

IC1 VIPER37LE Primary switching regulator ST

OPT KB817A Optoisolator Kingbright

TF 1715.0038 Flyback transformer Magnetica

Fs 1.6 A fuse Wickmann

NTC B57236S0160M NTC inrush current limiter EPCOS

If not otherwise specified, all resistors are ±5%, ¼ W

.

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Test board: design and evaluation AN4007

Figure 2. Electrical schematic

5V

L1

2.2uH

D2

STPS30L40CT

TF

C5

D1

1.5KE220

C1

220pF.

GND

100uF

R14

VR1

39k

TS431

C7

2.2nF

R9

120k

C4

1200uF

C3

1200uF

R6

330

R8

12k

OPTO3

KB817A

C9

10nF

R10

100k

GND

DRAIN

U1

D5

BAT46RL

D3

STTH1L06

D4

1N4148

R5

R2

3.9M

R4

150k

VIPER37LE

3.3

CONTROL

VDD

BR

CONT

FB

OPTO

KB817A

C13

2.2nF

C11

33nF

R13

47k

R12

39k

C2

BR

33uF

D7

1N4148

R1

2.2M

+

-

R3

2M

CM

2X25mH

3

C6

2

22nF – X2

4

1

C12

22uF

C14

22nF

6/33 Doc ID 022455 Rev 1

C10

10nF

R11

33k

JMP

R7

220

NTC

10

F1

1.5 A FUSE

D6

18V

AC IN AC IN

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AN4007 Test board: design and evaluation

Table 3. VIPER37LE power supply: transformer characteristics

Manufacturer Magnetica Values

Part number 1715.0038

Primary inductance 1.3 mH

Leakage inductance 3% nom

Primary to secondary turn ratio 16.2 ± 5%

Primary to auxiliary turn ratio 5.90 ± 5%

Insulation primary-secondary AC 4 kV (1 s – 2 mA)

Figure 3. Dimensional drawing

1.1 Output voltage characteristics

The output voltage of the board is measured in different line and load conditions.
shows the results: the output voltage variation range is a few tens of mV for all the tested
conditions.

All output voltages have been measured on the output connector of the board.

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Figure 4

Test board: design and evaluation AN4007

Figure 4. Line and load regulation

5.15

115Vac

5.10

5.05

Output voltage [V]

5.00

4.95

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Output current [mA]

230Vac

AM11343v1

1.2 Efficiency and light load measurements

The efficiency of the converter has been measured in different load and line voltage
conditions.

In accordance with the ENERGY STAR
efficiency measurements have been performed at 25%, 50% and 75% and 100% of the
rated output power, at both 115 V

Table 4. Efficiency at 115 V

Load I

25%0.754.973.734.7678.31%

50% 1.5 4.97 7.46 9.65 77.25%

75% 2.25 4.97 11.17 14.75 75.74%

100% 3 4.97 14.91 19.86 75.08%

OUT

Average efficiency 76.59%

®

average active mode testing efficiency method, the

and 230 VAC.

AC

AC

V

OUT

Ta b le 4

P

OUT

and

Ta bl e 5

P

show the results:

IN

Efficiency

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AN4007 Test board: design and evaluation

Table 5. Efficiency at 230 V

Load I

25% 0.75 4.97 3.73 4.9 76.07%

50% 1.5 4.965 7.45 9.61 77.50%

75% 2.25 4.965 11.17 14.45 77.31%

100% 3 4.95 14.85 19.3 76.94%

OUT

AC

V

OUT

Average efficiency 76.96%

P

OUT

P

IN

Figure 5. Efficiency vs. output power

79

78

77

76

EPA 2.0 limit

75

Efficiency [%]

74

73

115Vac
230Vac
average @115Vac
averege @230Vac

Efficiency

72

02468 10 12 14 16

1.3 No-load consumption

The input power of the converter was measured in no load condition, with brownout
protection disabled (see relevant
enabled in the entire input voltage range.

The converter in the no load condition works always in burst mode so that the average
switching frequency is reduced. The presence of the brownout resistor divider (R16, R17
and R18, see schematic in
increases the input power consumption due to the power dissipated across it.

It is worth noting that often, if the converter is used as the standby power supply for LCD
TVs, PDPs or other applications, the EMI line filter often coincides with the main power
supply line filter that heavily contributes to standby consumption even if the power needed
by the auxiliary power supply is very low.

Figure 2

Output power [W]

Section 2.4: Brownout protection

) and brownout protection

) does not affect the average switching frequency but

AM11344v1

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Test board: design and evaluation AN4007

Figure 6. No load consumption vs. input voltage

65

60

55

50

45

40

35

30

Input power [mW]

25

20

15

10

50 100 150 200 250 300

No brownout
With brownout

Input voltage [Vac]

AM11347v1

1.4 Light load consumption

Even though the ENERGY STAR program does not have other requirements regarding light
load performance, except no load consumption, the user very often requires the input power
consumption when the output is loaded with a few tens of mW output power. Such
measurements were performed at different loads with brownout protection both enabled and
disabled, the results are reported below. The application meets the new EuP Lot 6
requirements.

Figure 7. Light load consumption at different output power without brownout

450

400

350

300

250

200

150

100

50

30mW

50mW

100mW

250mW

0

50 100 150 200 250 300

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