Phase Cut Dimmable Non-isolated
Buck Converter for LED Retrofit Bulb with
ICL8002G & CoolMOS™ 600V C6
Application Note
Revision 1.1, 2012 -08 -03
Power Management & Multimarket
Edition 2012-08-03
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2012 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
The information given in this document shall in no event be regarded as a guarantee of conditions or
characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Infineon Technologies hereby disclaims any and all
warranties and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual
property rights of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please contact the
nearest Infineon Technologies Office ( www.infineon.com).
Warnings
Due to technical requirements, components may contain dangerous substances. For information on the types
in question, please contact the nearest Infineon Technologies Office.
Infineon Technologies components may be used in life-support devices or systems only with the express
written approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause
the failure of that life-support device or system or to affect the safety or effectiveness of that device or system.
Life support devices or systems are intended to be implanted in the human body or to support and/or maintain
and sustain and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other
persons may be endangered.
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
ICL8002G
Revision History: 2012-08-03, Version 1.1
Previous Version: 1.0
Page
Subjects (major changes since last revision)
17
Add “Production Tolerance and Normal Distribution”
Application Note
3
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
List of Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Technical Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
Demo Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6
TRIAC Based Dimmer Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7
Single Stage Power Factor Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8
Line Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9
Setup and Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1
Input / Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1.1
Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1.2
Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.2
Power Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.3
Operation Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.4
Output Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.5
Input Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.6
Power Factor Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.7
Output current regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.8
Phase Cut Dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.8.1
Test set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.8.2
Waveforms during dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.8.3
List of compatible TRIAC dimmers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.9
System Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.10 Protection Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.10.1 Output Open Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.10.2 Output Short-circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.11 Conducted EMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
10
Production Tolerance and Normal Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
11
Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
12
12.1
12.2
BOM and Power Inductor Spec . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Bill of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Power Inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
13
13.1
13.2
Common Questions and Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Q&A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Design and Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
14
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Application Note
4
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
1
Introduction
ICL8002G is a quasi-resonant PWM controller specially designed for high efficient offline LED driving
application. It can be configured for different topologies such as flyback and buck converter. This document
illustrates the ICL8002G in dimmable LED bulb application using the non-isolated buck topology. The ICL8002G
IC’s quasi-resonant operation mode, precise cycle-by-cycle peak current control, integrated PFC and phase-cut
dimming control, and various protections make it an outstanding system solution for dimmable LED bulbs.
The ICL8002G non-isolated bulb demo board shows high efficiency and power factor with single stage design.
Damping and bleeder circuit blocks were added to achieve high compatibility with wide range of dimmers. The
output current is well regulated over a wide input and output voltage range. Its compact form factor makes it
easy to fit into many LED lamp shapes and sizes.
Other available demo boards for ICL8001G/ICL8002G are designed with isolated flyback topology. If galvanic
isolation is not required, a non-isolated buck topology can be used with the following advantages:
•
•
Lower PCBA BOM cost due to less costly power inductor and lower voltage rated MOSFET
Smaller form factor due to more compact size of the power inductor
This demo board can be ordered with the sales code EVALLED-ICL8002G-B2.
2
•
•
•
•
•
•
•
•
•
List of Features
Smooth dimming curve with high dimmer compatibility
High efficiency (>86%)
High power factor (>0.95) with low THD ( 0.95
THD**
< 20%
Efficiency**
86%
*: Actual input and output power depends on the output
voltage **: Measured at 120Vac with output of 34.3V/295mA
Application Note
5
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
4
Demo Board
Both top and bottom side of the demo board EVALLED-ICL8002G-B2 are shown in Figure 1.
Figure 1 EVALLED-ICL8002G-B2 demo board (Dimension: 40x20x25mm)
5
Schematic
Figure 2 shows the schematic for a 10W non-isolation dimmable LED bulb application designed with ICL8002G.
Figure 2 EVALLED-ICL8002G-B2 schematic
6
TRIAC Based Dimmer Compatibility
TRIAC based dimmers work smoothly with resistive loads such as incandescent lamps. However, when
connected to non-resistive loads such as switch mode LED drivers flickering issue can happen primarily due to
insufficient hold-up current and due to current oscillation especially during TRIAC firing. Therefore, to improve
compatibility with TRIAC based dimmers, usually bleeder circuit and damping circuit are implemented in the
LED drivers.
In this design, the fusible resistor F1 is functioning as a fuse as well as a damping element to reduce oscillation and
inrush current. Moreover, both passive bleeder circuit (formed by R1 and C1) and active bleeder circuit (formed by
R3-R6, C3, C4, ZD1, Q1, and Q2) are incorporated to maintain input current above the hold-up current
Application Note
6
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
threshold of the TRIAC. When the input voltage is low, ZD1 as well as Q2 will not conduct. Q1’s gate is charged
by Vcc through R6. When Q1 turns on, the current through R5 helps the TRIAC maintain conduction. As input
voltage rises, ZD1 will pass current to trigger Q2. Once Q2 is on, Q1’s gate will discharge, turning off Q1.
Meanwhile TRIAC’s current is high enough for it to remain in conduction due to the increased current drawing
by the buck converter.
7
Single Stage Power Factor Correction
Single stage power factor correction (PFC) allows for a highly efficient, cost effective and compact LED driver.
In this demo board design, PFC is achieved by sensing the input mains voltage (via R8 and R10) and regulating
the peak current of the coupled inductor T1’s main winding (Pin 4 to Pin2) during each switching cycle to be
proportional to the input voltage.
The formula describing the relationship between the peak current and VR pin’s voltage is given by:
I
p pk
(t)
VVR (t) VPWM
G
R
V1(t) Vbe VPWM
G
R
V1(t)
(1)
G
RCS
where Ip-pk(t) is the peak current of the transformer’s primary winding; VVR(t) is the VR pin’s voltage; V1(t) is the
input voltage sensing signal at the base of Q3; Vbe is the transistor Q3’s base to emitter voltage; VPWM is the
IC’s internal offset voltage with typical value of 0.7V, which is compensated by Q3’s V be; GPWM is the IC’s
PWM gain; and RCS is the current sense resistor.
PWM
CS
PWM
CS
PWM
The ICL8002G operates the buck converter in quasi-resonant PWM mode, that means, the current of the
inductor’s main winding is in critical conduction mode. The high frequency sawtooth current in the main winding
is filtered by the output capacitor before flowing to the LED load. Meanwhile the high frequency component of
the input current is filtered by LC filters formed by L1, L2, C2, and C5. Input voltage and current waveforms in
half an AC cycle are illustrated in Figure 3.
Rectified input
Voltage
Primary peakcurrent
envelope
Inductor current
Average input
current
Figure 3 Voltage and current waveforms in half an AC cycle
As can be noted from Figure 3, the averaged input current is shaped to be approximately sinusoidal and thus
high power factor is achieved, with input current harmonics fulfilling the requirements of EN 61000-3-2 and ANSI
C82.77-2002 standard.
Application Note
7
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
The average output current mainly depends on the peak current of the main winding. As a rule of thumb, the
average output current can be calculated as
Io 0.29Ip pk
(2)
It can be also noted that the switching frequency varies with the instantaneous line voltage and reaches minimum
value when minimum line voltage reaches its peak value. Ignoring the zero crossing detection delay and voltage drop
on the MOSFET, shunt resistor, and the freeweeling diode, the minimum frequency is given by:
f
1
MIN
on
Vo(Vin_MIN 2 Vo)
1
T T
off
LI
p
1
(
p pk
V
1)
2V
V
o
o
in_MIN
L I
p p pk
V
2
(3)
in_MIN
where Ton and Toff are the ON and OFF time of the MOSFET respectively; Lp is the inductance value of the inductor
main winding; Vin-min is the minimum line voltage as specified in the design specification; and V o is the output
voltage.
Considering the system’s form factor, efficiency, and EMI performance, it is recommended to set minimum
switching frequency to between 80kHz and 100kHz by choosing proper primary inductance value.
8
Line Regulation
The power factor correction scheme described above also indicates that with higher input voltage, the output
current tends to increase due to higher VR pin voltage. Therefore to produce a stable output current (and lumen
output) versus mains voltage variations it is necessary to implement some compensation scheme to achieve
good line regulation.
In this design, the line regulation is achieved by the IC’s integrated foldback correction function as well as the
circuitry formed by R9, C10, D4, and R13. IC’s ZCV pin is able to detect the input voltage level through R12 and
the Vcc winding (T1’s Pin 7 to Pin8), allowing the IC to vary primary current sense voltage limit according to the
input voltage level. This means the primary current will be decreased when the input voltage increases. The
extent of the compensation can be adjusted with varying the value of R12.
Meanwhile C10, together with D4 and the transformer’s auxiliary winding (Pin1 to Pin8) will produce a negative
voltage which is proportional to the rectified input voltage. With a proper value of R9, the peak voltage level at
the base of Q3, and thus VR pin’s voltage, will be regulated against line voltage variation. The circuit formed by
R14, R15 and ZD3 will add a DC offset to the base of Q2 to prevent it from going to a negative voltage. This
offset alters the peak level of VR’s voltage and as a result determines the output current.
Fine tuning of resistance value of R9 is necessary to provide optimum compensation to the line voltage
variation. As a rule of thumb, R9 can be calculated with the following formula:
N
R9 R8
aux
Np
(4)
where Naux and Np are the number of turns of the coupled inductor T1’s auxiliary winding (Pin1 to Pin8) and
main inductor winding (Pin2 to Pin4) respectively.
Application Note
8
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9
Setup and Results
ATTENTION: LETHAL VOLTAGES ARE PRESENT ON THIS DEMO BOARD. DO NOT OPERATE
THE BOARD UNLESS YOU ARE TRAINED TO HANDLE HIGH VOLTAGE CIRCUITS. DO NOT
LEAVE THIS BOARD UNATTENDED WHILE IT IS POWERED UP.
9.1
Input / Output
9.1.1
Input
Connect AC line (90V-132V) to the red (Hot) and black (Neutral) wires. For dimming operation the phase cut
dimmer shall be connected to the input according to the dimmer’s instructions by its manufacturer.
9.1.2
Output
Connect LED module (30V~38V/300mA) to the yellow (positive) and white (negative) wires from the demo board.
Attention: As this is a NON-isolated design, high voltage exists at the output! An isolated AC source at the
input is advised to be used during evaluation of this demo board.
9.2
Power Up
The ICL8002G integrates a start-up cell to charge up the Vcc capacitor until it starts up successfully. Figure 4
demonstrates the start-up waveforms from mains voltage switch-on to light output.
Figure 4
Start-up waveforms: Rectified mains input voltage (C1, yellow), Controller Vcc (C2,
red), output voltage (C3, blue), and output current (C4, green)
9.3
Operation Waveforms
The ICL8002G is a quasi-resonant PWM controller and operates the buck converter in critical conduction mode.
Through zero crossing detection via ZCV pin, the ICL8002G turns on MOSFET when its drain voltage drops to the
Application Note
9
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
first valley point. This helps to reduce current spike as well as switching loss and thus improve both efficiency
and EMI performance. Figure 5 shows typical switching waveforms.
Figure 5
Typical operation waveforms: ZCV pin voltage (C1&Z1, yellow), shunt signal Vcs (C2&Z2,
red), drain voltage Vds (C3&Z3, blue) and primary winding’s current (C4&Z4, green) showing
quasi-resonant switching
9.4
Output Waveforms
The single stage PFC design inevitably produces double mains frequency ripple at the output. Increasing output
capacitance value helps reduce output ripple. However, this is often at the expense of the system’s form factor.
In this demo board design, the output capacitor (C9) is sized for an output current ripple which exhibits no
visible light modulation. Figure 6 shows the measured waveforms of output voltage and output current. The
modulation depth of the current ripple is about 25%.
Figure 6 Typical waveforms: Output voltage (C2, blue) and output current (C4, green)
Application Note
10
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9.5
Input Waveforms
Figure 7 shows the waveforms of input voltage, input current, and the current shunt voltage during normal
operation at 120Vac and full load.
Figure 7 Input voltage Vin (C2, blue), Input current Iin (C4, green) and shunt voltage Vcs (C2, red)
9.6
Power Factor Correction
The measured power factor and total harmonics distortion (THD) at different input voltages are shown in Figure
8. The power factor is above 0.95 over the whole input voltage range.
PF & THD vs. AC input voltage
THD
1
25%
0.98
20%
0.96
15%
0.94
10%
0.92
5%
T
H
D
Output Power
Power Factor
0.9
0%
80
90
100
110
120
130
140
Input Voltage [Vac]
Figure 8 Power Factor and THD versus line voltage
Application Note
11
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9.7
Output current regulation
Figure 9 shows the LED driver system’s output current versus line voltage. The output current is regulated
within +/-3% over the whole input voltage range.
Iout vs. AC input voltage
Output Current [mA]
300
290
280
270
260
250
80
90
100
110
120
130
140
Input Voltage [Vac]
Figure 9 Output current vs. input voltage
Figure 10 shows the LED driver system’s output current versus output voltage (LED module’s forward voltage).
With the number of LED changes from 11 to 13, which corresponds to forward voltage of 34.2V to 40.4V, the
output current is regulated within +/-2%.
Iout vs. Vout
Output current (mA)
LED current
Tolerance %
310
305
300
295
290
285
280
275
270
4%
3%
2%
1%
0%
‐1%
‐2%
‐3%
‐4%
34
36
38
40
Output Voltage
Figure 10 Output current vs. output voltage
Application Note
12
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9.8
Phase Cut Dimming
9.8.1
Test set-up
When evaluating dimming performance, the phase cut dimmer should be connected according to the
arrangement as shown in Figure 11.
LED Module
Offline LED Driver
Vac
AC
Phase cut dimmer
Designed with ICL8002G
Figure 11 Phase cut dimming arrangement
9.8.2
Waveforms during dimming
Figure 12 shows the waveforms of input voltage, input current, and the LED module’s current when the LED
driver is operated with a leading edge phase cut dimmer.
Figure 12 Waveforms during dimming operation: Input voltage Vin (C2, blue), Input current Iin (C1,
yellow) and LED current (C4, green)
Application Note
13
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9.8.3
List of compatible TRIAC dimmers
A variety of TRIAC dimmers were tested with this demo board. These dimmers were chosen based on
recommendations from customers and dimmer manufacturers. The table below lists the dimmers that exhibit no
flickering and shimmering when tested with the demo board.
Table 2
Compatible dimmers tested at input 120 Vac / 10 W
Manufacturer
Model
Power limit
Dimming range
Leviton
RPI06-1LW
600 W
7 – 100 %
Leviton
6684
600 W
6 – 100 %
Leviton
SureSlide 6633
600 W
5 – 100 %
Lutron
TT-300H-WH
300W
10 – 100 %
Lutron
DVCL-153P-WH
600 W
6 – 100 %
Lutron
SKYLARK S-600-WH
600 W
6 – 100 %
Lutron
D-600PH-DK
600 W
10 – 100 %
Lutron
LXLV-600PL-WH
450 W
5 – 100 %
Lutron
S-603PG-WH
600 W
8 – 100 %
Lutron
Ariadni/Toggler AY-600P
600 W
8 – 100 %
Lutron
Vareo V-600
600 W
15 – 100 %
Lutron
NT-600
600 W
10 – 100 %
GE
DI61ULM5
600 W
10 – 100 %
9.9
System Efficiency
Figure 13 shows the LED driver system’s efficiency versus line voltage, which exhibits high efficiency (>85%)
over the whole input voltage range due to the quasi-resonant operation.
Efficiency vs. AC input voltage
90.00%
Efficiency [%]
88.00%
86.00%
84.00%
82.00%
80.00%
80
90
100
110
120
130
140
Input Voltage [Vac]
Figure 13 LED driver efficiency vs. input voltage
Application Note
14
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
9.10
Protection Functions
The protection functions listed in Table 3 are provided with ICL8002G.
Table 3
ICL8002G protection functions
VCC Overvoltage
Auto Restart Mode
VCC Undervoltage
Auto Restart Mode
Output Overvoltage
Latched Off Mode
Output Short Circuit
Auto Restart Mode
Short Winding
Latched Off Mode
Over temperature
Auto Restart Mode
9.10.1
Output Open Circuit Protection
When output is left open (not connecting to LED load) during operation, the output voltage will rise and
accordingly the voltage produced by the auxiliary winding when MOSFET turns off will increase. This voltage is
detected by ZCV pin of ICL8002G via R7 and R12 . Output overvoltage protection will be triggered once this
voltage reaches the OVP threshold (Vzcovp = 3.7 V) and IC will go into Latched Off Mode. The power
consumption during Latched Off Mode is kept below 0.3W.
The output voltage can reach 43V and therefore, it is advised to connect proper LED loads before switching on
the power. Figure 14 shows some waveforms when powering up the LED driver with no load connected.
Figure 14
9.10.2
Waveforms during start-up without load: Input voltage at HV pin (C1, yellow), Vcc voltage
(C2, red), ZCV signal (C3, blue), and output voltage (C4, green)
Output Short-circuit Protection
In the case of an output short circuit, the IC will switch to Auto Restart Mode by means of VCC undervoltage
detection. Total input power consumption under this condition is below 0.7W. Figure 15 shows the waveforms
when powering up the LED driver with output short circuited.
Application Note
15
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
Figure 15
9.11
Waveforms during start-up with output short-circuited: Input voltage at HV pin (C1,
yellow), Vcc voltage (C2, red), MOSFET drain voltage (C3, blue), and output current (C4,
green)
Conducted EMI
The conducted EMI test is performed at 120Vac with full load condition. The EMI’s peak value is plotted against
quasi-peak limit of the FCC Class B and EN55015 (CISPR15). There is approximately 6dB margin observed.
Live
Neutral
Figure 16 Tested at 120Vac with full load. EN55015 Class B limit.
Application Note
16
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
10
Production Tolerance and Normal Distribution
In total 47 demo board samples have been tested and the output current of each board was recorded at the
o
same test condition (line voltage of 120Vac and ambient temperature of 25 C) to check the production
tolerance, which is contributed by both the IC and external components tolerance. Figure 17 shows the
distribution data of output current.
The result indicted that the output current tolerance is within +3%, and standard deviation is 3.62mA.
Figure 17 Production variation of output current (board to board deviation)
Application Note
17
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
11
Board Layout
A single layer PCB with dimension of 40x20mm and thickness of 0.8mm is used for this demo board. The
maximum height of the demo board (at C9) is 23.2mm. With its compact form factor, this demo board is able to
fit into many different LED lamps such as A19 bulb and Par30.
Figure 18 EVALLED-ICL8002G-B2 - Top and Bottom Layer
Figure 19 EVALLED-ICL8002G-B2 - Silkscreen Top and Bottom
Application Note
18
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
12
BOM and Power Inductor Spec
12.1
Bill of Material
Number Reference
Value
Description
Package
Part Number
Manufacturer
SO8
4×10
7mm Disc
SOT89
SOT323
SOT23
DPAK
4.9×7.5×9.0
1206
0603
12×5.5×10.5
1210
0603
0603
10×20
1206
DO-41
SOD80C
SMA
ICL8002G
EMC2-22RKI
V07E140P
BSS225
BC847BW
BC857B
IPD60R2K0C6
B32560J3224
GRM31CR72J153KW03L
GRM188R71H102KA01D
ECQ-E2224JF
GRM32ER71E226KE15L
GRM1885C1H560JA01D
GRM188R71H103KA01D
50ZLH330MT810X20
GRM31CR71H475KA12L
UF4004
BAV102
BYG20J
INFINEON
WELWYN
LITTELFUSE
INFINEON
INFINEON
INFINEON
INFINEON
TDK-EPCOS
MURATA
MURATA
PANASONIC
MURATA
MURATA
EE13
750341383
7447462152
MB6S-E3/80
MMSZ5241B-V-GS08
MMSZ4688-V-GS08
PDZ15B,115
Würth Elektronik
Würth Elektronik
VISHAY
VISHAY
VISHAY
NXP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
U1
F1
Z1
Q1
Q2
Q3
Q5
C1
C2
C4
C5
C6
C7
C8
C9
C10
D1
D2,D4
D3
ICL8002G
22OHM,2W
360V
600V 0.09A
45V 0.1A
45V 0.1A
600V 2.4A
250V 0.22uF
15nF 630V
50V 1nF
250V 0.22uF
25V 22uF
50V 56pF
50V 10nF
50V 330UF
50V 4.7uF
400V 1A
150V 250mA
600V 1.5A
IC
Fusible Resistor,±10%
VARISTOR,13.5J, 140Vrms
Small Signal Mosfet
NPN Transistors
PNP Transistor
MOSFET
Film Cap, 7.5mm Pitch
MLCC,X7R
MLCC,X7R
Film Cap, 10mm Pitch
MLCC,X7R
MLCC,COG
MLCC,X7R
Electrolytic Cap,Lo=10000H
MLCC,X7R
Ultrafast Rectifier Diode
Switching Diode
Ultrafast Rectifier Diode
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
T1
L1,L2
BD1
ZD1
ZD2
ZD3
R1
R2
R3
R4
R5
R6,R15
R7
R8
R9
R10
R11
R12
R13
R14
R14A
R14B
210uH
1.5mH 0.19A
600V 0.5A
11V
4.7V
15V
1K 1/2W
4K7
1.5M
604K
3.6K 3/4W
121K
3.48K
576K
118K
12K7
0R
20K
10R
33K
1R
Coupled inductor,210uH±10%
Np:Nvcc:Naux = 70:40:11
Filter Choke
Bridge Diode
Zener Diode,500mW
Zener Diode,500mW
Zener Diode,400mW
Metal Film Resistor,5%
Metal Film Resistor,5%
Metal Film Resistor,5%
Metal Film Resistor,5%
Metal Film Resistor,5%
Metal Film Resistor,1%
Metal Film Resistor,1%
Metal Film Resistor,1%
Metal Film Resistor,1%
Metal Film Resistor,1%
Metal Film Resistor,5%
Metal Film Resistor,1%
Metal Film Resistor,5%
Metal Film Resistor,5%
Metal Film Resistor,1%
TO-269AA
SOD123
SOD123
SOD323
1210
0603
1206
0603
2010
0603
0603
0805
0603
0603
0603
0603
0603
0603
0805
1R5
Metal Film Resistor,1%
0805
RUBYCON
MURATA
VISHAY
NXP
VISHAY
Figure 20 Bill Of Material
Application Note
19
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
12.2
Power Inductor
Figure 21 EVALLED-ICL8002G-B2 Inductor Design
Application Note
20
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
13
Common Questions and Troubleshooting Hints
13.1
Q&A
How does ICL8002G realize dimming control and power factor correction?
Both dimming control and PFC are achieved with the input mains voltage sensing with the VR pin. This signal is
used to set the peak current of the primary winding and consequently allows both PFC and phase-cut dimming
functionality by regulating the cycle energy.
Is it possible to test the demo board with different LED modules with big variations in total forward
voltages?
The operation range of output voltage is specified in Table 1. The demo board will switch into protection mode
when tested with LED load with out-of-range forward voltage either due to Vcc overvoltage protection or Vcc
undervoltage protection. Modifications on the transformer design are necessary for applications with different
output voltage.
13.2
Design and Troubleshooting Hints
Why is there no light output after the LED load is connected and power is on?
Please verify the following:
•
•
•
Connectivity of AC input and LED load
LED module’s polarity
Whether LED module’s forward voltage is out of the range specified in Table 1
How to change output current?
The easiest way to set the desired output current is to adjust the VR pin’s voltage and shunt resistor. However,
care must be taken to ensure that the transformer is not driven into saturation. Moreover, the VR pin’s voltage
should be kept below 3.7V for maximum power factor.
How to change the open circuit protection to Auto Restart Mode?
If Auto Restart Mode is preferred for output open circuit protection, R7 and/or R12 can be adjusted so that Vcc
overvoltage threshold (Vvccovp = 25V) is reached first before OVP threshold (Vzcovp = 3.7 V) is reached.
Please note that with changing R12, the voltage foldback correction will be affected and as a result the line
regulation will be affected. In this case R9 can be tuned for better line regulation.
Why is the LED flickering in my dimming application? How to improve?
Flickering can be either caused by IC auto-restart or by dimmer's uneven conduction phase angle. For the autorestart case, the ICL8002G’s Vcc voltage should be maintained between Vvccovp and Vvccoff over the whole
dimming range. This can be achieved by proper transformer turn ratio design and, if necessary, a voltage
regulation circuit for the Vcc. For dimmer’s uneven conduction case, it is advised to tune the damping and
bleeder circuits.
How to improve system efficiency?
For applications which require higher efficiency, first of all, an active damper circuit can be used to replace the
lossy passive damper circuit. Switching frequency can be reduced so as to minimize the switching loss and this
may require bigger inductor size. Low ESR capacitor can be used for the output capacitor to improve efficiency.
Using a higher current rated MOSFET for Q5, however, may not necessarily produce higher efficiency as the
switching loss may dominate the total power loss of the MOSFET.
How to modify the board for non-dimmable LED bulb application?
For non-dimmable application, the highlighted damping and bleeder circuits as shown in Figure 2 can be
removed for better efficiency and cost reduction.
Application Note
21
Version 1.1, 2012-08-03
AN-EVALLED-ICL8002G-B2
Phase Cut Dimmable Non-isolated Buck Converter for LED Retrofit Bulb with ICL8002G & CoolMOS™ 600V C6
How to reduce BOM cost?
For low cost application, the active bleeder circuit (formed by R3-R6, C3, C4, ZD1, Q1, and Q2) can be
removed. Please note that dimming performance may be affected. If lightning surge performance requirement is
not stringent, a 250V rated MOSFET can be used for Q2 while a 500V rated MOSFET can be used for Q5 for
cost reduction.
14
References
ICL8002G Datasheet at www.infineon.com/ledoffline
Design Guidelines for ICL8001G/ICLS8082G at www.infineon.com/ledoffline
Application Note
22
Version 1.1, 2012-08-03
www.infineon.com
Published by Infineon Technologies AG
工商网监
湘ICP备2023018690号
