FEBFL7701_L30U003A - Fairchild Semiconductor

User Guide for

FEBFL7701_L30U003A

2.4 W LED Ballast Using FL7701

Featured Fairchild Product:

FL7701

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about this evaluation board to:

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Table of Contents

1. Introduction ............................................................................................................................... 3

1.1. General Description .......................................................................................................... 3

1.2. Key Features ..................................................................................................................... 3

1.3. Internal Block Diagram .................................................................................................... 4

2. General Specifications for Evaluation Board ........................................................................... 5

3. Photographs of the Evaluation Board ....................................................................................... 6

4. Printed Circuit Board ................................................................................................................ 7

5. Schematic .................................................................................................................................. 8

6. Bill of Materials ........................................................................................................................ 8

7. Performance of Evaluation Board ............................................................................................. 9

7.1. Typical Waveforms: Startup .......................................................................................... 10

7.2. Operating Frequency & Minimum Duty ........................................................................ 11

7.3. Typical Waveforms: Steady State .................................................................................. 12

7.4. Typical Waveforms: Abnormal Mode (LED Open) ...................................................... 15

7.5. Typical Waveforms: Abnormal Mode (Inductor Short Condition) ............................... 16

7.6. Power Factor (PF) at Rated Load Condition .................................................................. 17

7.7. Total Harmonic Discharge (THD) Performance ............................................................ 18

7.8. System Efficiency .......................................................................................................... 19

7.9. Thermal Performance ..................................................................................................... 20

7.10. Electromagnetic Interference (EMI) Results .............................................................. 22

8. Revision History ..................................................................................................................... 24

This FEBFL7701_L30U003A Evaluation Board can be identified by the silkscreen

marking FL7701 Board on the top side of the PCB. This user guide supports the

evaluation board for the FL7701, FEBFL7701_L30U003A. It should be used in

conjunction with the FL7701 datasheet as well as Fairchild’s application notes and

technical support team. Please visit Fairchild’s website at www.fairchildsemi.com or the

evaluation board page http://www.fairchildsemi.com/products/evaluationboards/.

1. Introduction

This document describes the proposed solution for a universal-input 2.4W LED ballast

using the FL7701. The input voltage range is 90 VRMS – 265 VRMS and there is one DC

output with a constant current of 85 mA at 28 VMAX. This document contains general

description of FL7701, the power supply specification, schematic, bill of materials, and

the typical operating characteristics.

1.1. General Description

The FL7701 LED lamp driver is a simple IC with PFC function. The special “adopted

digital” technique automatically detects input voltage condition and sends an internal

reference signal, resulting in high power factor. When an AC input voltage is applied to

the IC, the PFC function is automatically enabled. Otherwise, when a DC input is applied

to the IC, the PFC function is automatically disabled. The FL7701 does not require a bulk

capacitor (electrolytic capacitor) for supply rail stability, which can significantly affect

LED reliability.

1.2. Key Features

 Digitally Implemented Active PFC Function

 Built-in Self-Biasing HV Startup Circuit

 Application Input Range: 80 VAC ~ 308 VAC

 AOCP Function with Auto-Restart Mode

 Built-in Over-Temperature Protection

 Cycle-by-Cycle Current Limit

 Current-Sense Pin Open Protection

 Low Operating Current: 0.85 mA (Typical)

 Under-Voltage Lockout with 5 V Hysteresis

 Programmable Oscillator Frequency

 Programmable LED Current

 Analog Dimming Function

 Fixed Soft-Start Function

 Precise Internal Reference: ±3%

1.3. Internal Block Diagram

Figure 1. Internal Block Diagram

Pin Descriptions

Pin Symbol Description

1 CS

Current Sense. Limits output current, depending on the sensing resistor

voltage. The CS pin is also used to set the LED current regulation.

2 OUT

Output. Connects to the MOSFET gate.

3 VCC

Supply Voltage. Supply pin for stable IC operation; ZCD signal detection used

for accurate PFC function.

4 RT

Resistor. Programmable operating frequency using an external resistor

connected to this PIN and the IC has fixed frequency when this pin is left open

or floating.

5 ADIM

Analog Dimming. Connects to the internal current source and can change the

output current using an external resistor. If ADIM is not used, connect a 0.1 µF

bypass capacitor between ADIM and GND.

6 GND

GROUND. Ground for the IC.

7 NC No Connection

8 HV

High Voltage. Connect to the high-voltage line and supply current to the IC

2. General Specifications for Evaluation Board

All data for this table was measured at an ambient temperature of 25°C

Table 1. Summary of Features and Performance

Description Symbol Value Comments

Input Voltage Range

VIN,min 90 V

VIN,nom 220 V

VIN,max 265 V

AC Input Frequency fIN,min 47 Hz

fIN,max 64 Hz

Output Voltage/Current VOUT 28 V Note 1

IOUT 85 mA

Output Power Output Power 2.41 W Note 2

Efficiency > 75% At full load

Temperature

TFL7701 < 71.5°C

At full load (all at open frame, room

temperature / still air)

TMOSFET < 59.5°C

TINDUCTOR < 57.7°C

PCB Size 20 mm (width) x 32 mm (length) x 13 mm

(height)

Initial Application LED bulb

Notes:

1. The output current has ILEDPK ripple. To reduce ripple current, use a large electrolytic capacitor in

parallel with the LED. Ensure the capacitor voltage rating is high enough to withstand an open-LED

condition or use a Zener diode for protection.

2. The output power is not equal to the apparent power due to the slight phase shift between the output

voltage and current.

3. Photographs of the Evaluation Board

Figure 2. Photograph Top View (20 mm x 32 mm x 13 mm)

Figure 3. Photograp h Bottom View (20 mm x 32 mm x 13 mm)

Figure 4. Photograph Side View (20 mm x 32 mm x 13 mm)

4. Printed Circuit Board

Figure 5. PCB, Top Side

Figure 6. PCB, Bottom Side

5. Schematic

Figure 7. Schematic of Evaluation

6. Bill of Materials

Item

No. Part

Reference Part Number Qty. Description Manufacturer

1 U1 FL7701 1 Main Controller Fairchild

Semiconductor

2 BD MB6S 1 0.5 A / 600 V Bridge Diode Fairchild

Semiconductor

3 C1 MPE 630V223K 1 22 nF / 630 VAC 10%, Polypropylene Sungho

4 C2 MPE 630V333K 1 33 nF / 630 VAC 10%, Polypropylene Sungho

5 C3 C0805C101K3RACTU 1 100 pF / 25 V SMD Capacitor 2012 Kemet

6 C4 C1206C225K3PACTU 1 2.2 µF / 25 V SMD Capacitor 3216 Kemet

7 D1 UF4007 1 1 A / 1 kV Ultra Fast Recovery Fairchild

Semiconductor

8 D2 1N4148 1 1 A / 100 V Small Signal Diode Fairchild

Semiconductor

9 L1, L2 R06153KT00 2 1.5 mH Radial Inductor R6.5x7.5 Bosung

10 L3 R06402KT00 1 4 mH Radial Inductor R6.5x7.5 Bosung

11 R1 RC1206JR-07680RL 1 680Ω SMD Resistor 3216 Yageo

12 R2 RC1206JR-0710KL 1 10kΩ SMD Resistor 3216 Yageo

13 R3 RC0805JR-0724KL 1 24kΩ SMD Resistor 2012 Yageo

14 R4 RC0805JR-07510RL 1 510Ω SMD Resistor 2012 Yageo

15 R5 RC1206JR-073RL 1 3Ω SMD Resistor 3216 Yageo

7. Performance of Evaluation Board

Table 2. Test Condition & Equipments

Test Temperature TA = 25°C

Test Equipments

AC Source: PCR500L by Kikusui

Power Meter: PZ4000 by Yokogawa

Oscilloscope: Waverunner 64Xi by Lecroy

EMI Test Receiver: ESCS30 by ROHDE & SCHWARZ

Two-Line V-Network: ENV216 by ROHDE & SCHWARZ

Thermometer: CAM SC640 by FLIR SYSTEMS

LED: EHP-AX08EL/GT01H-P03 (3W) by Everlight

7.1. Typical Waveforms: Startup

Figure 8 through Figure 11 show the typical startup performance at different input

voltage conditions. When AC input voltage is applied to the system, the FL7701

automatically operates in AC Mode after finishing an internally fixed, seven-cycle, soft-

start period. Figure 10 and Figure 11 show the soft-start characteristics when a DC input

voltage is applied.

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 8. Soft-Start Characteristics, AC Mode, 90 VAC

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 9. Soft-Start Characte ristics, AC Mode, 265 VAC

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 10. Soft-Start Characteristics, DC Mode,

100 VDC

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 11. Soft-Start Characteristics, DC Mode,

200 VDC

7.2. Operating Frequency & Minimum Duty

The programmable switching frequency is between 20 kHz ~ 250 kHz, determined by

selecting the RT resistor value. If no RT resistor is used (RT pin OPEN), the FL7701

default switching frequency is set to 45 kHz. The maximum duty ratio is fixed below

50% and has a fixed minimum typical on-time of 400 ns. There are two crucial points to

design properly. The first is consideration of the minimum duty ratio at minimum input

voltage because the FL7701 is limited to 50% duty ratio. The second consideration is

minimum on-time at maximum input voltage condition. The FL7701 cannot control

output power when the operating conditions are such that the required on-time is less than

the 400 ns minimum on-time.

CH1: VCC, CH2: VDRAIN, CH3: VLED, CH4: ILED

Figure 12. Operating Frequency & Minimum Duty

Minimum on time:

1.12µs

Switching frequency:

69.91kHz

7.3. Typical Waveforms: Steady State

Figure 13 through Figure 22 show the normal operation waveform by input voltage &

input frequency. The output voltage and current maintains a certain output level with

120 Hz ripple, as shown in the test results in Table 3.

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 13. Input Voltage: 90 VAC, Input Frequency:

47 Hz

CH1: VCC, CH2:

V

DRAIN, CH3: VLED, CH4: ILED

Figure 14. Input Voltage: 90 VAC, Input Frequency:

64 Hz

H1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 15. Input Voltage: 110 VAC, Input Frequency:

47 Hz

H1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 16. Input Voltage: 110 VAC, Input Frequency:

64 Hz

Typical Operating Waveforms: Output Characteristics

CH1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 17. Input Voltage: 180 VAC, Input Frequency:

47 Hz

CH1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 18. Input Voltage: 180 VAC, Input Frequency:

64 Hz

CH1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 19. Input Voltage: 220 VAC, Input Frequency:

47 Hz

CH1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 20. Input Voltage: 220 VAC, Input Frequency:

64 Hz

H1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 21. Input Voltage: 265 VAC, Input Frequency:

47 Hz

H1:

V

CC, CH2:

V

DRAIN, CH3:

V

LED, CH4: ILED

Figure 22. Input Voltage: 265 VAC, Input Frequency:

64 Hz

Table 3. Output Characteristics by Input Voltage & Frequency

47 Hz 64 Hz

VLED(RMS) I

LED(RMS) V

LED(RMS) I

LED(RMS)

90 VAC 27.91 V 84.45 mA 27.90 V 84.58 mA

110 VAC 27.99 V 84.41 mA 28.02 V 84.49 mA

180 VAC 28.13 V 84.94 mA 28.10 V 84.86 mA

220 VAC 28.12 V 85.66 mA 28.14 V 85.77 mA

265 VAC 28.17 V 87.05 mA 28.13 V 87.05 mA

7.4. Typical Waveforms: Abnormal Mode (LED Open)

Figure 23 and Figure 24 show the open-load condition test method and result. When the LED

disconnects from the s ystem, the IC cannot opera te because the HV pin is disc onnected.

Figure 23. Open-Load Condition Test

CH1: VCC, CH2: VDRAIN, CH3: VLED, CH4: ILED

Figure 24. Test Results of Open-Load Condition

7.5. Typical Waveforms: Abnormal Mode (Inductor Short

Condition)

Figure 25 and Figure 26 show the test method and result of an inductor short condition.

The FL7701 uses an abnormal over-current protection (AOCP) function, limiting the

current on RCS in the event of an inductor short condition.

Figure 25. Inductor Short Condition

CH1: VCS, CH2: VDRAIN, CH3: VLED, CH4: ILED

Figure 26. Test Results of Inductor Short Condition

When CS pin voltage reached

2.5V, AOCP operates after

internal delay time 70ns (typical)

7.6. Power Factor (PF) at Rated Load Condition

Figure 27 shows the system PF performance for the entire input voltage range (90 V to

265 V) at different input frequency conditions (47 Hz, 64 Hz). The PF slightly changes

according to the input frequency but can achieve over 86% at 265 VAC condition.

Figure 27. Power Factor

Table 4. Power Factor Test Result s

Input Voltage Power Factor

90 VAC 47 Hz 96.31

64 Hz 97.34

110 VAC 47 Hz 96.72

64 Hz 96.89

180 VAC 47 Hz 94.41

64 Hz 93.74

220 VAC 47 Hz 92.49

64 Hz 91.09

265 VAC 47 Hz 89.71

64 Hz 86.56

50

55

60

65

70

75

80

85

90

95

100

90 110 180 220 264

PF_47Hz

PF_64Hz

[

%

]

[

V

AC

]

7.7. Total Harmonic Discharge (THD) Performance

Figure 28 shows the THD performance at different input frequencies. Test results are

quite similar, except the 90 VAC condition, but meets international regulations

(under 30%).

Figure 28. Total Harmonic Distortion Performance

Table 5. Total Harmonic Distortion Test Results

Input Voltage Frequency THD (%)

90 VAC 47 Hz 20.99

64 Hz 21.82

110 VAC 47 Hz 22.26

64 Hz 22.46

180 VAC 47 Hz 24.96

64 Hz 25.31

220 VAC 47 Hz 25.50

64 Hz 25.84

265 VAC 47 Hz 25.75

64 Hz 26.72

0

5

10

15

20

25

30

90 110 180 220 264

THD_47Hz

THD_64Hz

[

V

AC

]

[

%

]

7.8. System Efficiency

Figure 29 shows system efficiency results for different AC input voltage frequency

conditions. As shown, the input frequency has negligible effect on system efficiency.

Figure 29. System Efficien cy

Table 6. Efficiency Test Results

Input Voltage Frequency Efficiency (%)

90 VAC 47 Hz 83.56

64 Hz 83.83

110 VAC 47 Hz 83.36

64 Hz 83.46

180 VAC 47 Hz 80.04

64 Hz 80.06

220 VAC 47 Hz 77.68

64 Hz 77.69

265 VAC 47 Hz 75.11

64 Hz 75.22

50

55

60

65

70

75

80

85

90

95

100

90 110 180 220 264

Efficiency_47Hz

Efficiency_64Hz

[

%

]

[

V

AC

]

7.9. Thermal Performance

Figure 30 through Figure 37 show the steady-state thermal results with different input

voltage conditions. Inductor L3 has the highest temperature on the top side of the PCB

due to copper resistance. The FL7701 has the highest temperature on the bottom side of

the PCB due to power loss associated with the high-voltage device. The IC temperature i s

66.5°C for the 220 VAC input condition.

Figure 30. Thermal Test Result, Bottom-Side

Temperature at 90 VAC Condition (IC) Figure 31. Thermal Test Result, Top-Side Temperature

at 90 VAC Condition (Inductor)

Figure 32. Thermal Test Result, Bottom-Side

Temperature at 110 VAC Condition (IC) Figure 33. Thermal Test Result, Top-Side Temperature

at 110 VAC Condition (Inductor)

Figure 34. Thermal Test Result, Bottom-Side

Temperature at 220 VAC Condition (IC) Figure 35. Thermal Test Result, Top-Side Temperature

at 220 VAC Condition (Inductor)

Figure 36. Thermal Test Result, Bottom-Side

Temperature at 264 VAC Condition (IC) Figure 37. Thermal Test Result, Top-Side Temperature

at 264 VAC Condition (Inductor)

Table 7. Temperature Performance by Input Voltage

Input Voltage TIC T

MOSFET T

INDUCTOR

90 VAC 47.6°C 46.2°C 47.8°C

110 VAC 51.4°C 46.9°C 47.8°C

220 VAC 66.5°C 55.0°C 54.6°C

265 VAC 71.5°C 59.5°C 57.7°C

7.10. Electromagnetic Interference (EMI) Results

EMI test measurements were conducted in observance of CISPR22 criteria, which has

tighter stricter limits than CISPR15 for lighting applications.

Figure 38. EMI Test Results, Conducted Emissio n - Line at 11 0VAC Input Condition,

Full Load (10-LED Series)

Figure 39. EMI Test Results, Conducted Emission-Neutral at 110 VAC Input Condition,

Full Load (10-LED Series)

Figure 40. EMI Test Results, Conducted Emission-Neutral at 220 VAC Input Condition,

Full Load (10-LED Series)

Figure 41. EMI Test Results, Conducted Emission-Neutral at 220 VAC Input Condition,

Full Load (10-LED Series)

8. Revision History

Rev. Date Description

1.0.0 Nov. 2011. First issue

1.0.1 Dec. 2011. Update IC temperature

1.0.2 Feb. 2012.

Modified, edited, formatted document. Changed User Guide number from

FEB_L030 to FEBFL7701_L30U003A

1.0.3 Aug. 2012 Formatted document

WARNING AND DISCLAIMER

Replace components on the Evaluation Board only with those parts shown on the parts list (or Bill of Materials) in the Users’ Guide. Contact an

authorized Fairchild representative with any questions.

This board is intended to be used by certified professionals, in a lab environment, following proper safety procedures. Use at your own risk. The

Evaluation board (or kit) is for demonstration purposes only and neither the Board nor this User’s Guide constitute a sales contract or create any kind

of warranty, whether express or implied, as to the applications or products involved. Fairchild warrantees that its products meet Fairchild’s published

specifications, but does not guarantee that its products work in any specific application. Fairchild reserves the right to make changes without notice to

any products described herein to improve reliability, function, or design. Either the applicable sales contract signed by Fairchild and Buyer or, if no

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