Fairchild FEB-L031-1 service manual

User Guide for

FEB-L031-1

Evaluation Board

7.8W LED Ballast at Low Line

Featured Fairchild Product:

FL7701

Direct questions or comments

about this evaluation board to:

“Worldwide Direct Support”

Fairchild Semiconductor.com

Table of Contents

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

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

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

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

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

3. Photographs............................................................................................................................... 6

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

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

6. Bill of Materials ........................................................................................................................ 9

7. Inductor Design ....................................................................................................................... 10

8. Performance of Evaluation Board ........................................................................................... 11

8.1. Typical Waveforms: Startup .......................................................................................... 12

8.2. Operating Frequency & Minimum Duty ........................................................................ 13

8.3. Typical Waveforms: Steady State .................................................................................. 14

8.4. Typical Operating Waveforms: Output Characteristics ................................................. 15

8.5. Typical Waveforms: Abnormal Mode (LED-Open) ...................................................... 16

8.6. Typical Waveforms: Abnormal Mode (Inductor Short) ................................................ 17

8.7. System Efficiency .......................................................................................................... 18

8.8. Power Factor at Rated Load Condition .......................................................................... 19

8.9. Total Harmonic Distortion Performance ....................................................................... 20

8.10. Thermal Performance ..................................................................................................... 21

8.11. Electromagnetic Interference (EMI) Test Results ......................................................... 23

9. Revision History ..................................................................................................................... 24

This user guide supports the evaluation kit for the FL7701. 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

1. Introduction

This document describes the proposed solution for low line input, 7.8W LED ballast using the FL7701. The input voltage range is 90V output with a constant current of 250mA at 31V. 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 and integrated switching MOSFET. The special “adopted digital” technique automatically detects input voltage condition and sends an internal reference signal, resulting in high power factor (PF). When AC input voltage is applied to the IC, PFC function is automatically enabled. When DC input voltage is applied to the IC, PFC function is automatically disabled. The FL7701 does not require a bulk capacitor (electrolytic capacitor) for supply rail stability, which can significantly improve LED reliability.

– 150V

RMS

.

and there is one DC

RMS

1.2. Features

 Digitally Implemented Active PFC Function

(No Additional Circuit Necessary for High PF)

 Built-in HV Supplying Circuit: Self Biasing  AOCP Function with Auto-Restart Mode  Built-in Over-Temperature Protection (OTP)  Cycle-by-Cycle Current Limit  Low Operating Current: 0.85mA (Typical)  Under-Voltage Lockout with 5V Hysteresis  Programmable Oscillation Frequency  Programmable LED Current  Analog Dimming Function  Soft-Start Function  Precise Internal Reference: ±3%

1.3. Internal Block Diagram

Figure 1. Block Diagram

Pin No. Symbol Description

1

2

3

4

5

6

7

8

CS Current Sense. Limits output current depending on the sensing resistor voltage

OUT OUT. Connects to the MOSFET gate. VCC

RT

ADIM

GND GROUND. Ground for the IC.

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

VCC. Supply pin for stable IC operation and IC uses this pin for catching ZCD

signal to make internal artificial reference.

RT. Programmable operating frequency using external resistor and IC has fixed frequency even though this pin open or floating.

Analog Dimming. Connect to the internal current source. Can change output

current using external resistor. Connect small capacitor at non-dimming condition.

No Connection.

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

V

90V Minimum Input Voltage

Input Voltage

Range

AC Input Frequency

Output Voltage

Output Current

Output Power

(1)

(2)

IN.MIN

V

IN.NORMAL

V

Freq

V

OUT,MAX

V

OUT,NORMAL

V

I

OUT.NORMAL

CC Deviation < ±1.6%

110V Normal Input Voltage

150V Maximum Input voltage

IN.MAX

47Hz Minimum Input Frequency

IN.MIN

64Hz Maximum Input Frequency

IN.MAX

33V Maximum Output Voltage

31V Normal Output Voltage

29V Minimum Output Voltage

OUT,MIN

250mA Normal Output Current

Line Input Voltage Change:

Output Power 7.8W

90~150VAC

Efficiency

Temperature

PCB Size

Initial Application

> 82% At Full Load

T

< 56°C

FL7701

T

< 67°C

DM filter

T

FRD,ES3J

T

MOSFET

T

inductor

< 53°C

< 58°C

< 46°C

At full load (all at open-frame, room

temperature / still air)

28mm (width) x 52mm (length )x

20mm (height)

LED Bulb

Notes:

1. The output current has I

ripple. To reduce ripple current, use a large electrolytic capacitor

LEDPK

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

Figure 2. Top-View (28mm x 52mm)

Figure 3. Bottom-View (28mm x 52mm)

Figure 4. Side-View (20mm)

4. Printed Circuit Board

Figure 5. Top Side

Figure 6. Bottom Side

5. Schematic

Figure 7. Schematic