AN3111
Application note
18 W single-stage offline LED driver
Introduction
With the rapid development of high brightness LEDs, SSL (solid state lighting) has begun to
move from being a niche market to penetrating residential markets. There is a large
potential market for the residential application of SSL, and CFL (compact fluorescent lamp)
retro-fit is part of it. Standardization of SSL products is helping to lead the growth of the
market. In September 2007, the US department of energy (DOE) issued ENERGY STAR®
criteria for SSL products. To meet the ENERGY STAR specifications for SSL products, the
power factor of power supply must be higher than 0.7 for residential applications. For CFL
retro-fit applications, cost, size, and reliability are very important. To achieve a high power
factor, either passive PFC (power factor correction) or active PFC can be used. Typically,
passive PFC requires large passive components, which makes it difficult to maintain a small
size. Traditional active PFC circuits require a two-stage topology, which entails a boost stage
for PFC, and then buck or flyback for current regulation of the LEDs. The cost of the two
stages is high. In this application note, a non-isolated, soft-switched, single-stage high
power factor offline LED driver is introduced. The buck-boost converter is chosen for this
application due to its simplicity and low cost. The converter operates with constant peak
current for constant power control, and in transition mode (boundary mode between CCM
and DCM) to achieve soft switching, using the L6562A controller. High power factor is
achieved by reshaping the peak current near the zero crossing of the input AC line.
Figure 1.
18 W single-stage offline LED driver board
For this particular design, the LED string consists of 18, 1 W white LEDs in series. Isolation
is not required. The goal of the design is high power factor, high efficiency, simplicity, and
low cost.
February 2011
Doc ID 16815 Rev 2
1/23
www.st.com
Contents
AN3111
Contents
1
Circuit design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
STEVAL-ILL027V1 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . 13
3
STEVAL-ILL027V2 demonstration board . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1
Schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2
BOM for the STEVAL-ILL027V2 demonstration board . . . . . . . . . . . . . . . 15
3.3
STEVAL-ILL027V2 description for EU voltage range . . . . . . . . . . . . . . . . 15
3.4
Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2/23
Doc ID 16815 Rev 2
AN3111
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Bill of material for the STEVAL-ILL027V1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bill of material for the STEVAL-ILL027V2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Doc ID 16815 Rev 2
3/23
List of figures
AN3111
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
4/23
18 W single-stage offline LED driver board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Block diagram for the L6562A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Schematic diagram of the single-stage LED driver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Illustration of key waveforms of the converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Inductor current and multiplier input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Input voltage and input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
LED voltage and LED current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Switching waveform of MOSFET Q1: conclusions when Vout > Vin . . . . . . . . . . . . . . . . . 11
Switching waveform of MOSFET Q1: conclusions when Vout < Vin . . . . . . . . . . . . . . . . . 11
STEVAL-ILL027V2 schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Output LED current and voltage for input voltage 230 V / 50 Hz . . . . . . . . . . . . . . . . . . . . 17
Output LED current and voltage for input voltage 180 V / 50 Hz . . . . . . . . . . . . . . . . . . . . 17
Output LED current and voltage for input voltage 260 V / 50 Hz . . . . . . . . . . . . . . . . . . . . 18
Open load measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Short-circuit measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
EMI measurement - detector average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
EMI measurement - detector quasi-peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
LED current vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Efficiency vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
LED current vs. LED number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Doc ID 16815 Rev 2
AN3111
1
Circuit design
Circuit design
The L6562A is a current mode PFC controller operating in transition mode (boundary mode
between CCM and DCM). Its linear multiplier enables the converter to shape the AC input
current waveform following the input voltage. The block diagram of the L6562A is shown in
Figure 2 below. For more detailed information regarding the L6562A, please refer to the
device datasheet and application notes.
Figure 2.
Block diagram for the L6562A
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Figure 3 shows the schematic of the proposed single-stage LED driver. If the inductor
current is constant, the power of the converter is constant. As the LED string is
a constant voltage load, we can obtain a constant current in the LED string. This makes it
possible to leave out the LED current sensing, therefore simplifying the circuit design. If the
inductor current is constant, then the power factor of the circuit is very poor. The input
current waveform is greatly distorted during line voltage zero crossing. If there is a way to
reduce the current amplitude near the line voltage zero crossing, the power factor can be
improved. The L6562A PFC controller is used to achieve this objective. The idea is to
reduce the current amplitude near the line voltage zero crossing, which results in an
improved power factor.
Doc ID 16815 Rev 2
5/23
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6/23
Figure 3.
Circuit design
AN3111
Schematic diagram of the single-stage LED driver
!-V
AN3111
Circuit design
The proposed circuit runs at constant peak current. The current sensing voltage is set for 1
V, which is the clamping voltage of the current sensing comparator of the L6562A. The
voltage of the LED string is sensed on the INV pin of the L6562A through a coupled winding.
The turn ratio of the coupled inductor is designed so that the feedback voltage is lower than
2.5 V in normal operating conditions, so the error amplifier is saturated at maximum level
which sets the max. current sensing voltage to 1 V. Therefore, the peak current of the
inductor is fixed at a level determined by the sensing resistor value. As the peak current of
the inductor is constant, the input power is constant. The LED voltage is considered
constant, and the current into the LED can also be considered constant. If the load (the
LEDs) is open, the reflected output voltage on the INV pin is above a certain level, and the
controller shuts down to provide open load protection.
If the inductor current is controlled at constant level all the time, then the power factor is very
poor. The multiplier of the L6562A is used to reshape the current amplitude near the line
voltage zero crossing to improve the power factor. The rectified sine waveform is sampled at
the MULT pin. The output of the multiplier, which is the current setting, is lower than setting
the level near the line voltage zero crossing. In this way, the power factor of the converter is
improved significantly.
Design procedure:
●
Input voltage:Vin ( θ ) =
2 ⋅ Vin ⋅ sin ( θ,Vin
)
= 120V
●
Output voltage: 18 LEDs in series, Vout=54 V
●
Output current: Iout=350 mA
The design variable is the peak current of the inductor (Ipk), and the inductance (L).
When Q1 is turned on, the inductor is charged to Ipk. The ON time is:
Equation 1
Ton(θ) =
L * Ipk
Vin(t)
Toff(θ) =
L * Ipk
Vout
The OFF time is:
Equation 2
The period of the switching cycle is:
Equation 3
T(θ) = Ton(θ) + Toff(θ) =
L * Ipk L * Ipk
+
Vin(θ) Vout
The duty cycle (D) is:
Equation 4
D(θ) =
Ton(θ)
Vout
=
T(θ)
Vout + Vin(θ)
Doc ID 16815 Rev 2
7/23
Circuit design
AN3111
The frequency is:
Equation 5
fsw(θ) =
1
1
Vout * Vin(θ)
=
(
)
T L * Ipk Vin(θ) + Vout
The switching frequency varies during the line cycle, which is good for EMI.
The max. frequency occurs at peak input voltage:
Equation 6
fsw max =
1
Vout * Vpk
(
)
L * Ipk Vpk + Vout
The input power is:
Equation 7
P=
π1
∫ 2 * L * Ipk
2
0
* fsw(θ)dt
Equation 8
P=
1
* Ipk *
2
π
∫ D(θ) * Vin(θ)dθ
0
The integration term of Equation 8 is a constant value, so the power is determined by Ipk
only. There is no simple solution form for the integration term. The average value of the input
voltage and duty cycle can be used to perform the estimation. After Ipk is calculated, the
inductance can be determined according to the desired switching frequency range.
The average input voltage over half-cycle at 120 VAC line is:
Equation 9
Vave =
π
∫ Vpk * sin(θ)dθ = 108 V
0
The average duty cycle is:
Equation 10
Dave =
Vout
= 0.333
Vave + Vout
Therefore:
Equation 11
Ipk =
Pin
= 1.2 A
1
* Vave * Dave
2
After the current is determined, it is necessary to choose the right inductance value. The
inductance affects the running frequency. The maximum switching frequency below 200 kHz
has been chosen.
8/23
Doc ID 16815 Rev 2
AN3111
Circuit design
From Equation 6, we have:
Equation 12
L=
1
Vout * Vpk
(
)
fsw max* Ipk Vpk + Vout
L = 200 μH
A 1 Ω current sensing resistor can be used in the application. To better handle the high
current, two SMT 2 Ω resistors are implemented.
Operating principles:
The operation of the converter can be described as follows:
●
●
●
●
●
●
●
The period of t0 to t3 is near the line voltage zero crossing. The period of t4 to t7 is
around the peak line voltage.
[t0,t1], Q1 is turned on at time t0. The inductor current reaches its peak at t1. Near the
line voltage zero crossing, the peak amplitude is lower than the constant value Ipk.
[t1,t2] Q1 is turned off at t1. The inductor current decreases to zero at t2.
[t2,t3] the drain voltage of Q1 starts to fall at t2, and reaches zero at t3. The ZCD pin of
the controller detects the ZCD signal low and turns on Q1 again at t3. Q1 is turned on
at zero voltage.
[t4,t5], Q1 is turned on at time t4. The inductor current reaches its peak at t4. The peak
amplitude is the constant value Ipk.
[t5,t6] Q1 is turned off at t5. The inductor current decreases to zero at t6.
[t6,t7] the drain voltage of Q1 starts to fall at t6, and reaches its minimum value at t7,
but it does not reach zero. The ZCD pin of the controller detects the ZCD signal low and
turns on Q1 again at t7. Q1 is turned on at reduced voltage.
Figure 4.
Illustration of key waveforms of the converter
The MOSFET Q1 operates zero voltage turn-on when the instant input voltage is lower than
the output voltage. It is turned on at reduced voltage when the input voltage is higher than
the output voltage. Therefore, it is a partial soft-switched converter.
Doc ID 16815 Rev 2
9/23
Circuit design
AN3111
The efficiency of the circuit is 88%, and the power factor is 0.85. Key waveforms are shown
in the figures below.
Figure 5 shows the envelope of inductor current and input signal at the MULT pin.
Figure 5.
Inductor current and multiplier input
Figure 6 shows the input voltage and current.
Figure 6.
Input voltage and input current
Figure 7 shows output LED current and voltage.
10/23
Doc ID 16815 Rev 2
AN3111
Figure 7.
Circuit design
LED voltage and LED current
Figure 8 and 9 show the MOSFET switching waveforms. When the input line voltage is lower
than the output voltage, zero voltage turn-on is achieved. When the input voltage is higher
than the output voltage, the MOSFET is turned on at reduced voltage.
Figure 8.
Switching waveform of MOSFET
Q1: conclusions when Vout > Vin
Figure 9.
Switching waveform of MOSFET
Q1: conclusions when Vout < Vin
Fault conditions:
1.
Open load
If the LED string is disconnected from the circuit, the output capacitor can be charged to
a very high voltage if there is no overvoltage protection. The protection threshold voltage
Vovp is set as 75 V. R7 and R10 sense the reflected voltage through the coupled inductor
with a 4 to 1 turn ratio (N). The error amplifier of the L6562A is used to shut down the chip if
overvoltage is detected.
Doc ID 16815 Rev 2
11/23
Circuit design
AN3111
Equation 13
Vovp
R10
*
≤ 2.5
N
R7 + R10
2.
Short-circuit
If the load is shorted, the reflected voltage is zero, and the VCC of the L6562A collapses.
Therefore, it is automatically protected from short-circuits. In both fault conditions, the input
power is less than 0.5 W.
12/23
Doc ID 16815 Rev 2
AN3111
STEVAL-ILL027V1 demonstration board
2
STEVAL-ILL027V1 demonstration board
Table 1.
Bill of material for the STEVAL-ILL027V1
Reference
Part description / part number
Package
C1
82 µF / 100 V
Axial
C5
10 µF / 35 V
SMT
C6
0.1 µF / 50 V
805
C7
1 nF / 50 V
805
C8, C10
0.27 µF/250 V ECQ-E2274KF
Metal Poly.
C9
0.68 µF/250 V ECQ-E2684KB
Metal Poly.
D1
1 A/600 V diode bridge DF06S
SMT
D3
1N4148WS
SMT
D7, D8
STTH1L06A
SMA
L1
20 mH CM choke 744821120
Q1
STD5NM50
DPAK
R3
10 kΩ
805
R4
12 kΩ
1206
R5
100 Ω
805
R6, R11
2Ω
1206
R7
130 kΩ
805
R8
100 kΩ
805
R14
100 kΩ
1206
R9
510 kΩ
1206
R10
20 kΩ
805
R12
200 kΩ
1206
T1
200 µH couple inductor 750310347 Rev01
U1
L6562A
Manufacture
STMicroelectronics™
Wurth Electronics Midcom
STMicroelectronics
Wurth Electronics Midcom
SO-8
Doc ID 16815 Rev 2
STMicroelectronics
13/23
STEVAL-ILL027V2 demonstration board
3
AN3111
STEVAL-ILL027V2 demonstration board
An original demonstration board (STEVAL-ILL027V1) was redesigned in order to
demonstrate this design concept also for the EU input voltage range. In fact, it means that
the board can operate with the input voltage between 188 V and 265 V AC. The LED
constant current is again set to 350 mA using the same output LED power 18 W. All required
board modifications and measurements, comparing with the STEVAL-ILL027V1, are
described in the following sections. The demonstration board for the EU input voltage range
has the order code; STEVAL-ILL027V2.
3.1
Schematic diagram
Figure 10. STEVAL-ILL027V2 schematic diagram
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14/23
Doc ID 16815 Rev 2
AN3111
STEVAL-ILL027V2 demonstration board
3.2
BOM for the STEVAL-ILL027V2 demonstration board
Table 2.
Bill of material for the STEVAL-ILL027V2
N
Q
Reference
Value
Package / class
Manufacturer
Orderable part
number
1
1
C1
100 µF / 100 V
Electrolytic
capacitor
Panasonic
ECA2AM101
2
1
C5
2.2 µF / 50 V
Ceramic
capacitor 1210
AVX
12105C225KAT2A
3
1
C6
4
1
C7
1 nF / 50 V
Ceramic
capacitor 1206
5
2
C8, C10
470 nF / ~305 V AC
Foil capacitor
EPCOS
B32922C3474K
6
1
C9
150 nF / ~305 V AC
Foil capacitor
EPCOS
B32922C3154M
7
2
R3, R4
12 kΩ
Resistor 1206
8
1
R5
33 Ω
Resistor 0805
9
2
R6, R11
2.7 Ω
Resistor 1206
10
1
R7
130 kΩ
Resistor 0805
11
3
R8, R12, R16
100 kΩ
Resistor 0805
12
2
R9, R15
510 kΩ
Resistor 1206
13
1
R10
20 kΩ
Resistor 0805
14
1
R14
100 kΩ
Resistor 1206
15
1
U1
L6562AD
PFC controller
STMicroelectronics
L6562AD
16
1
Q1
STD11NM50N
Power MOSFET
STMicroelectronics
STD11NM50N
17
1
D1
1 A / 250 V
Diode bridge
18
1
D3
19
1
D7
STTH3R06
Ultrafast diode
STMicroelectronics
STTH3R06S
20
1
D8
STTH1R06
Ultrafast diode
STMicroelectronics
STTH1R06A
21
1
T1
Transformer
Wurth Electronics
750310347
22
1
L1
Common mode
choke
Wurth Electronics
744821120
3.3
Not connected
Not connected
STEVAL-ILL027V2 description for EU voltage range
This section describes all modifications done on the STEVAL-ILL027V1 in order to change
the input voltage range from 120 V AC to 230 V AC. These modifications are demonstrated
on the STEVAL-ILL027V2.
In order to supply the STEVAL-ILL027V2 from the EU voltage range, it is necessary to
change the input foil capacitors C8, C9, and C10, because their maximum voltage is only
250 V DC (STEVAL-ILL027V1). The capacitors C8 and C10 were replaced by capacitor
470 nF / 305 V AC. Due to their size, the PCB layout was redesigned in order to fit the bigger
Doc ID 16815 Rev 2
15/23
STEVAL-ILL027V2 demonstration board
AN3111
capacitor package on the original design. The capacitors C8 and C10 470 nF / 305 V were
selected, because, thanks to this value, EMI behavior is fulfilled as demonstrated in
Figure 16 and 17. The capacitor C9 was replaced by the capacitor 150 nF / 305 V AC.
Maximum input voltage can be up to 362 V (265 V x √ 2) and therefore at least two SMD
resistors must be used for sensing the input voltage. An additional resistor, R16 = 100 kΩ,
is connected in series with R12 and the additional resistor, R15 = 510 kΩ, is connected in
series with R9.
Also the voltage divider used for the MULT pin is recalculated in order to have the correct
voltage on the MULT pin. The highest voltage on the MULT pin is presented for maximum
input voltage 265 V AC. In this case the voltage on the MULT pin is done by the following
equation:
Equation 14
Vin max × R3
362 × 12000
- = 4.2V
Vmult = ---------------------------------------- = -------------------------------------------------------------------12000 + 510000 + 510000
R3 + R9 + R15
Absolute maximum rating for the MULT pin is 8 V, which means that such a margin is high
enough to correctly operate even with maximum input voltage 265 V AC.
The next modification is to change the sense resistors R6 and R11, because these resistors
are used to set the level of constant LED current. The resistors R6 and R11 were replaced
by resistor 2R7.
Regarding the power MOSFET capability, it is possible to calculate its maximum drain
source voltage. Assume that maximum output LED voltage is approximately 72 V (18 LEDs
with maximum forward voltage 4 V) and then maximum drain source voltage is:
Equation 15
V ds = Vin max ×
2 + V led max = 265 ×
2 + 72 = 445V
For this kind of topology the switching losses are higher for higher input voltage and
therefore the power MOSFET with better current capability is selected for the input voltage
230 V AC. The STD11NM50N power MOSFET is used for the STEVAL-ILL027V2
demonstration board.
Maximum reverse voltage on diode D7 is also 445 V, when the power MOSFET is ON.
Ultrafast diode D7 STTH3R06A with maximum repetitive reverse voltage 600 V was
selected for this application.
Electrolytic capacitor C5 = 10 µF / 35 V is replaced by the small SMD ceramic capacitor
2.2 µF / 50 V as there is a size limitation on the board.
The transformer's number of turns can be used exactly the same as on the original design,
because the output LED voltage is transformed to the auxiliary winding when the MOSFET
is OFF in the same ratio as on the original design. For the output LED power 18 W and
constant LED current 350 mA, the LED voltage is 51.4 V. This voltage is reflected to the
auxiliary winding. The transformer isolation is 500 V DC and so the transformer can be used
in this application for EU input voltage range. The others components are without any
change.
16/23
Doc ID 16815 Rev 2
AN3111
3.4
STEVAL-ILL027V2 demonstration board
Measurement
Figure 11, 12 and 13 show output LED current and voltage waveforms. The LED current is
slightly changed with input voltage, because it is 354 mA for 230 V, 318 mA for 180 V and
358 mA for 260 V. The LED current vs. input voltage characteristic is demonstrated in
Figure 18.
Figure 11. Output LED current and voltage for input voltage 230 V / 50 Hz
Figure 12. Output LED current and voltage for input voltage 180 V / 50 Hz
Doc ID 16815 Rev 2
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STEVAL-ILL027V2 demonstration board
AN3111
Figure 13. Output LED current and voltage for input voltage 260 V / 50 Hz
In case the output LEDs are disconnected, STEVAL-ILL027V2 has designed an open load
protection. Figure 14 shows open load protection after connecting mains voltage 230 V AC.
As can be seen, output voltage is regulated to 78 V.
Figure 14. Open load measurement
Figure 15 shows short-circuit protection. As soon as the voltage on the VCC pin of the
L6562A reaches the turn-on threshold (capacitor C5 is charged via resistors R12 and R16),
the device starts switching (there is output current present) and the voltage VCC decreases,
because output voltage is almost 0 V and so the capacitor C5 cannot be supplied via the
transformer from the output voltage. As soon as the voltage on the VCC pin of the L6562A
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STEVAL-ILL027V2 demonstration board
reaches the turn-off threshold, the device stops switching and the capacitor C5 is again
charged via resistors R12 and R16 and the cycle is repeated.
Figure 15. Short-circuit measurement
The STEVAL-ILL027V2 demonstration board is also tested for EMI behavior. The EN55015
(CISPR15) standard describes limits and methods for the measurement of radio disturbance
characteristics of electrical lighting and similar equipment. STEVAL-ILL027V2 fulfills this
standard, as demonstrated in Figure 16 and 17.
Figure 16. EMI measurement - detector average
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Figure 17. EMI measurement - detector quasi-peak
Figure 18 shows LED current for the input voltage between 180 and 260 V AC. Minimum
measured LED current is 318 mA for 180 V and maximum measured LED current is 358 mA
for 260 V. Figure 19 shows efficiency for different input voltages. The efficiency is 71% for
input voltage 230 V AC. Figure 20 demonstrates LED current for a different number of LEDs
connected as the load. If 15 LEDs are connected (LED forward voltage is 47 V), the LED
current is 358 mA. If 19 LEDs are connected (LED forward voltage is 59 V), the LED current
is 331 mA.
Figure 18. LED current vs. input voltage
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STEVAL-ILL027V2 demonstration board
%FFICIENCY;=
Figure 19. Efficiency vs. input voltage
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Figure 20. LED current vs. LED number
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Conclusion
4
AN3111
Conclusion
Running at transition mode provides the benefit of lower switching losses and spread of the
EMI spectrum. This buck-boost converter achieves constant power by operating at constant
peak current, and high power factor is achieved by reshaping the current waveform near the
zero crossing of the line voltage. This single-stage buck-boost converter provides a costeffective solution for offline non-isolated LED applications. This single-stage LED driver has
open load and short-circuit protection.
5
6
Reference
1.
ENERGY STAR® requirements for SSL
2.
3.
AN966 application note
L6562A datasheet
Revision history
Table 3.
Document revision history
Date
Revision
10-Feb-2010
1
Initial release.
2
Corrected Figure 4, section “2.2 18 W single-stage offline LED driver
for EU voltage range” to section “2.5 STEVAL-ILL027V1
modifications for EU voltage range” replaced by Section 3: STEVALILL027V2 demonstration board, corrected typo in Section 1: Circuit
design and Section 2: STEVAL-ILL027V1 demonstration board.
08-Feb-2011
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Changes
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