Fairchild FEBFL7701_L31H008A User Manual
User Guide for
FEBFL7701_L31H008A
7.8 W LED Ballast Using FL7701
Featured Fairchild Product:
FL7701
Direct questions or comments
about this evaluation board to:
“Worldwide Direct Support”
Fairchild Semiconductor.com
© 2012 Fairchild Semiconductor Corporation 1 FEBFL7701_L31H008A • Rev.1.0.2
Table of Contents
1. Introduction ............................................................................................................................... 3
1.1. General Description ........................................................................................................ 3
1.2. Features .......................................................................................................................... 3
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 ........................................................................................................................ 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 Waveforms: Abnormal Mode (LED Open) .................................................... 16
8.5. Typical Waveforms: Abnormal Mode (Inductor Short) .............................................. 17
8.6. System Efficiency ........................................................................................................ 18
8.7. Power Factor at Rated Load Condition ........................................................................ 19
8.8. THD Performance ........................................................................................................ 20
8.9. Thermal Performance ................................................................................................... 21
8.10. EMI Test Results .......................................................................................................... 23
9. Revision History ..................................................................................................................... 24
© 2012 Fairchild Semiconductor Corporation 2 FEBFL7701_L31H008A • Rev.1.0.2
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 an universal input, 2.4W LED ballast
using the FL7701. The input voltage range is 187 V
output with a constant current of 250 mA at 31 V
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.
– 264 V
RMS
. This document contains general
MAX
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
Application Input Range: 80 V
~ 308 VAC
AC
AOCP Function with Auto-Restart Mode
Built-in Over-Temperature Protection (OTP)
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 Oscillation Frequency
Programmable LED Current
Analog Dimming Function
Soft-Start Function
Precise Internal Reference: ±3%
© 2012 Fairchild Semiconductor Corporation 3 FEBFL7701_L31H008A • Rev.1.0.2
Figure 1. Block Diagram
Table 1. Pin Definitions
Pin No. Symbol Description
1 CS
2 OUT
3 VCC
4 RT
5 ADIM
6 GND
7 NC No Connection.
8 HV
Current Sense. Limits output current, depending on the sensing resistor voltage.
The CS pin is also used to set the LED current regulation.
OUT. Connects to the MOSFET gate.
VCC. Supply pin for stable IC operation, ZCD signal detection, and used for
accurate PFC function.
RT. Programmable operating frequency using an external resistor. The IC has a
fixed frequency when this pin is open or floating.
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.
GROUND. Ground for the IC.
High Voltage. Connects to the high-voltage line and supplies current to the IC.
© 2012 Fairchild Semiconductor Corporation 4 FEBFL7701_L31H008A • Rev.1.0.2
2. General Specifications for Evaluation Board
All data for this table was measured at an ambient temperature of 25°C.
Table 2. Summary of Features and Performance
Description Symbol Value Comments
V
187 V
IN,min
Input Voltage Range
Input Frequency
Output Voltage/Current
Output Power
(2)
Output Power 7.8 W
(1)
Efficiency >78% At Full Load
Temperature
PCB Size
Initial Application LED Bulb
Notes:
1. The output current has I
in parallel with the LED. Ensure the capacitor voltage rating is high enough to withstand an openLED 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.
V
220 V
IN,nom
V
264 V
IN,max
f
47 Hz
IN,min
f
64 Hz
IN,max
V
OUT
I
OUT
T
FL7701
T
MOSFET
T
DIODE
T
INDUCTOR
T
HV RESISTOR
250 mA
< 72°C
< 60°C
< 66°C
< 58°C
< 67°C
31 V
At Full Load (all at open-frame, room
temperature / still air)
20 mm (width) x32 mm (length)
x13 mm (height)
ripple. To reduce ripple current, use a large electrolytic capacitor
LEDPK
© 2012 Fairchild Semiconductor Corporation 5 FEBFL7701_L31H008A • Rev.1.0.2
3. Photographs of the Evaluation Board
Figure 2. Top-View (PCB) (28 mmx52 mmx18 mm)
Figure 3. Top View (28 mm x 52 mm x 18 mm) (Mounted Housing)
Figure 4. Side View (28 mm x 52 mm x 18 mm)
© 2012 Fairchild Semiconductor Corporation 6 FEBFL7701_L31H008A • Rev.1.0.2
4. Printed Circuit Board
Figure 5. Top Side
Figure 6. Bottom Side
© 2012 Fairchild Semiconductor Corporation 7 FEBFL7701_L31H008A • Rev.1.0.2
5. Schematic
L1 15mH
C5 1nF
D1 ES3J
Fuse
1A/250V
BD
47nF/630V
C1
33nF/630V
R1
560R
L2 10mH
D2
C3 100pF
1N4148
R3 510R
R4 2.4R
C2
C4 1µF
R6 OPEN
CS
OUT
VCC
RT
U1
HV
NV
GND
ADIM
R2 56k
L3
5.5mH
Q1
FQN1N60C
R5 2.4R
Figure 7. Schematic of Evaluation Board
© 2012 Fairchild Semiconductor Corporation 8 FEBFL7701_L31H008A • Rev.1.0.2
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