AC Direct LED Lighting Driver IC
AN-SW5903A
SW5903A
Non-isolation type AC Direct LED Lighting Driver IC
Application note
(AN-SW5903A)
Rev 0.1 : Dec. 05, 2013
PR Announcement
Information provided by Silicon Works is believed to be accurate and reliable. However, no responsibility is
assumed by Silicon Works for its use, nor for any infringements of patents or other rights of third parties that
may result from its use. Specifications subject to change without notice.
No license is granted by implication or otherwise under any patent or patent rights of Silicon Works.
Trademarks and registered trademarks are the property of their respective owners.
Rev 0.0
Silicon Works Co., Ltd.
707 Tamnip-dong, Yuseong-gu
Daejeon, Korea 305-510
Tel : 82-42-712-7700
Fax: 82-42-710-7728
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AC Direct LED Lighting Driver IC
AN-SW5903A
REVISION HISTORY
Revision
Date
Remark
Rev. 0.0
May. 27, 2013
First issued
Rev. 0.1
Dec.05, 2013
NC pin name and description were changed
Rev 0.0
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AC Direct LED Lighting Driver IC
AN-SW5903A
TABLE OF CONTENTS
1. Introduction ............................................................................................................................................. 6
1.1. Description ............................................................................................................... 6
1.2. Package .................................................................................................................... 6
1.3. Features .................................................................................................................... 7
2. Theory ...................................................................................................................................................... 8
2.1. LED Properties ......................................................................................................... 8
2.2. DIAC .......................................................................................................................... 9
2.3. TRIAC .......................................................................................................................10
2.4. LED Dimming........................................................................................................... 11
3. Application Information ........................................................................................................................ 12
3.1. Reference Circuit.....................................................................................................12
3.2. Bill of Materials ........................................................................................................13
3.3. PCB Layout ..............................................................................................................14
3.4. PCB (Printed Circuit Board)....................................................................................14
3.5. PBA (Printed Board Assembly) ..............................................................................15
4. Pin Configuration and Functionality ................................................................................................... 16
4.1. Package QFN-20 ......................................................................................................16
4.2. Pin Configuration ....................................................................................................16
5. Design Information ............................................................................................................................... 17
5.1. Current for Channels...............................................................................................17
5.2. LED Quantity for Channels .....................................................................................18
5.3. VCOMP (VAC Compensation) .................................................................................19
5.4. OTP (Over Temperature Protection) .......................................................................20
6. Packaging Information ......................................................................................................................... 21
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AC Direct LED Lighting Driver IC
AN-SW5903A
LIST OF FIGURES
Figure 1. Pin Configuration (Top, Bottom) ........................................................................................ 6
Figure 2. LED Pin Configuration ........................................................................................................ 8
Figure 3. Current-Voltage Characteristic of LED ……………………................................................. 8
Figure 4. Symbol of DIAC …………………………………………......................................................... 9
Figure 5. Characteristic Curve of DIAC ............................................................................................. 9
Figure 6. Symbol of TRIAC ............................................................................................................... 10
Figure 7. Characteristic Curve of TRIAC .......................................................................................... 10
Figure 8. Forward Phase – Dimmer Maximum On ........................................................................... 11
Figure 9. Forward Phase – Dimmer Minimum On ............................................................................ 11
Figure 10. Reverse Phase – Dimmer Maximum On .......................................................................... 11
Figure 11. Reverse Phase – Dimmer Minimum On ........................................................................... 11
Figure 12. Application Circuit of SW5903A ......................................................................................... 12
Figure 13. Single SW5903A Drive PCB Layout .................................................................................... 14
Figure 14. Single SW5903A Drive PCB ................................................................................................ 14
Figure 15. Single SW5903A Drive PBA .............................................................................................. 15
Figure 16. Pin Configuration ............................................................................................................. 16
Figure 17. Channel Switching with Respect to Input Voltage Level .............................................. 17
Figure 18. Example of LED Quantity for AC Input Voltage ............................................................. 18
Figure 19. VCOMP Power Compensation Waveform …………………................................................... 19
Figure 20. VCOMP Power Compensation Graph .................................................................................. 19
Figure 21. Package Dimensions ...................................................................................................... 21
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AC Direct LED Lighting Driver IC
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LIST OF TABLES
Table 1. Features ………........................................................................................................................ 7
Table 2. Bill of Materials ...................................................................................................................... 13
Table 3. Pin Configuration of QFN-20 …............................................................................................. 17
Table 4. Channel Current Calculation …………………......................................................................... 18
Table 5. Total LED Operation …........................................................................................................... 19
Table 6. Power Compensation for AC Input Voltage ......................................................................... 21
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AC Direct LED Lighting Driver IC
AN-SW5903A
1. Introduction
1.1. Description
The Light Emitting Diodes (LEDs) are used as indicator lamps in many devices and are increasingly
used for other lighting.
The SW5903A is an AC Direct driving LED controller IC. It is able to replace other lighting systems
that are using AC voltage directly such as light bulb, halogen lamp and so on. It will give much
convenience to the design because it requires a small number of external components.
The SW5903A will help engineers to produce excellent products in LED lightings for energy
efficiency, design efficiency, cost efficiency, and so on.
1.2. Package
QFN-20
Figure1. Pin Configuration (Top, Bottom)
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1.3. Features
SW5903A
AC Input Voltage Range
Power
85V ~ 265V
2~10W @110V /
Channels
Maximum current
4~20W @220V
Four channels
160mA @ CH4 (CH4 is the largest)
Power Factor Correction
> 0.97 (@ 220V)
Power Efficiency
< 97% (@220V)
EMI
Protection
No internal high frequency noise generation
OTP, Inherent OCP, OVP free(Channel)
Very small number of external components for application
Etc.
Embedded four constant current drivers composed of 450V MOSFET device
Table1. Features
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AC Direct LED Lighting Driver IC
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2. Theory
2.1. LED Properties
The Light Emitting Diodes (LEDs) are composed of materials that
easily emit light such as GaAs and GaP. If a diode is under forwardbias condition, holes and electrons are recombined and it will emit
light with color like green, red, yellow etc.
When a current flows through a LED, it can only flow in one way, and
fixed voltage is measured at the both ports of the LED.
Unlike any
resistors, the voltage across the LED doesn’t change as current flow
through it.
An I-V characteristic graph of LED is in Figure 3.
The current barely flow until voltage is above 0 volts, and when it
reaches its threshold voltage, the amount of current flows rapidly
increase as shown below. Such characteristic is called diode's
constant voltage dropping characteristic.
Figure2. LED Pin Configuration
Forward Current(I)
IF
VR
Reverse Voltage(V)
IR
VF
Forward Voltage(V)
Reverse Current(I)
Figure 3. Current – Voltage Characteristic of LED
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AC Direct LED Lighting Driver IC
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2.2. DIAC
DIAC(Diode for Alternating Current) is composed of two electrodes; A1 and A2.
A1
A2
Figure4. Symbol of DIAC
DIAC operates same as two Shockley diodes connected in parallel.
It is an AC (Alternating Current) diode that conducts current only after its break over voltage
(around 30 V) has been reached momentarily
When this occurs, diode enters the region of negative dynamic resistance, leading to a decrease in
the voltage drop across the diode and, usually, a sharp increase in current through the diode. The
diode remains "in conduction" until the current through it drops below a value characteristic for the
device, called the holding current. Below this value, the diode switches back to its high-resistance
(non-conducting) state. This behavior is bidirectional, meaning typically the same for both directions
of current.
IF
IH
VR
-VBR(R)
0
VF
VBR(F0)
- IH
IR
Figure5. Characteristic Curve of DIAC
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AC Direct LED Lighting Driver IC
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2.3. TRIAC
TRIAC (Triode for alternating Current) is used for controlling AC power, and it is much like DIAC
with a gate (trigger) electrode.
A1
G
A2
Figure6. Symbol of TRIAC
TRIAC does not need to reach break over voltage to turn itself on unlike DIAC, but it needs a
current pulse for triggering on its gate.
Basically TRIAC is SCR connected together in parallel
sharing a common gate. But current can flow in any direction on TRIAC depends on the polarity of
gate triggered with respect to the A1 terminal.
IA
IG2
IG1
IG0
IH0
IH1
IH2
-VA
VBR(R0) VBR(R1) VBR(R2)
0
VA
VBR(F2) VBR(F1) VBR(F0)
- IH2
- IH1
- IH0
-IG0
-IG1 -IG2
-IA
Figure7. Characteristic Curve of TRIAC
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AC Direct LED Lighting Driver IC
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2.4. LED Dimming
LED is an eco-friendly light source which has high resistance against pressure or vibration. LED
light brightness is easily controlled, and it leads to saving extra energy.
LED dimming (phase cut dimming) is typically composed of TRIAC, DIAC, resistors and condenser,
etc.
Among those components, TRIAC and DIAC work as system on-off switch which makes it
possible to have dimming option.
There are two ways to operate dimming.
-
Positive angle/Leading edge dimming: forward phase operation.
-
Negative angle/Trailing edge dimming: reverse phase operation.
Forward phase operation dimmer decides when the dimmer should turn on by a switch when an
input voltage zero crossing happens.
On the other hand, reverse phase dimmer decides when the
dimmer should turn off by a switch when an input voltage zero crossing happens.
Figure8. Forward Phase – Dimmer Maximum On
Figure9. Forward Phase – Dimmer Minimum On
Figure10. Reverse Phase – Dimmer Maximum On
Figure11. Reverse Phase – Dimmer Minimum On
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3. Application Information
3.1. Reference Circuit
SW5903A is a Non-isolation-type AC Direct LED Lighting Driver IC.
Using AC directly has much more benefits than using DC directly.
-
High efficiency
-
Small form factor
-
Low system cost
-
A wide range of input voltage(application) (85V ~ 265V)
-
Long life system configuration ; no external transformer / high voltage electrolytic capacitor
-
Very small number of external components for application
Figure12. Application Circuit of SW5903A
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3.2. Bill of Materials
Symbol
Value
Size
Manufacturer
6mm X 6mm
Silicon Works
Comment
IC1
SW5903A
Fuse
AC Fuse
SPT Fuse / 250V / 0.5A
Varistor
275VAC
Varistor / 275VAC
Bridge
600V0.5A
RCOMP1
3M / 3M
3216
110V : 3MΩ,
RCOMP2
(110V
/ 220V)
24K
/ 12K
2012
110V : 24KΩ, 220V : 12KΩ / RES 1%, 0.125W
CCOMP
(110V / 220V)
1nF
2012
CAP MLCC 1nF 50V 2012
RISET
2.5Ω
2012
RES 1%, 0.125W 2012
CCDLY
10nF
2012
CAP MLCC 10nF 25V 2012
CPDC
2.2uF
2012
CAP MLCC 2.2uF 25V 2012
CVDD
2.2uF
2012
CAP MLCC 2.2uF 25V 2012
CVCC
10uF
2012
CAP MLCC 10uF 25V 2012
TO-269AA
Non-isolation-type AC Direct LED Lighting Driver IC
MB6S SMD / 600V / 0.5A
220V : 3MΩ / RES 5%, 0.25W
Table2. Bill of Materials
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3.3. PCB Layout
< Top Layer >
Figure13. Single SW5903A Drive PCB Layout
3.4. PCB (Printed Circuit Board)
< Top >
Figure14. Single SW5903A Drive PCB
Rev 0.0
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3.5. PBA (Printed Board Assembly)
< Top >
Figure15. Single SW5903A Drive PBA
Rev 0.0
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4. Pin Configuration and Functionality
4.1. Package QFN-20
Figure16. Pin configuration
4.2. Pin Configuration
Pin No.
Name
IN/OUT
Rating [V]
Description
2
VAC
IN
Typ. 110V/220V
IC Supply input (85VAC ~ 265VAC )
3
CH4
IN
Typ. 50V
Channel 4 for LED channel current
4
CH3
IN
Typ. 50V
Channel 3 for LED channel current
5
CH2
IN
Typ. 50V
Channel 2 for LED channel current
6
CH1
IN
Typ. 50V
Channel 1 for LED channel current
8
VCOMP
IN/OUT
Typ. 6.5V
VAC compensation
9
PDC
IN/OUT
Typ. 6.5V
External capacitor for peak detection of VIN
10
RISET
IN/OUT
Typ. 0.5V
LED channel current set pin
16
GNDA
-
17
CDLY
IN/OUT
Typ. 6.5V
External capacitor for Channel On delay
18
VDD
IN/OUT
Typ. 6.5V
Internal regulation voltage
20
VCC
IN/OUT
Typ. 18V
Pre-driving regulation voltage
Analog GND
Table3. Pin Configuration of QFN-20
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5. Design Information
5.1. Current for Channels
Current load at each channel is decided by external RISET resistor and internal channel amplifier’s
Vref voltage level.
The relationship between external RISET resistor and channel current is explained in the table 5.
No.
Calculation
Example (RISET=2.5 Ω)
Channel vs. Current ratio
1
CH1 Current = 0.10(Vref) / RRISET
1
0.10 / 2.5 = 40 mA
2
CH2 Current = 0.30(Vref) / RRISET
3
0.30 / 2.5 = 120 mA
3
CH3 Current = 0.35(Vref) / RRISET
3.5
0.35 / 2.5 = 140 mA
4
CH4 Current = 0.40(Vref) / RRISET
4
0.40 / 2.5 = 160 mA
Table4. Channel Current Calculation
Vrectify
I_CH1 I_CH2 I_CH3
I_CH4
I_CH3 I_CH2 I_CH1 I_CH1 I_CH2 I_CH3
I_CH4
I_CH3 I_CH2 I_CH1
Figure17. Channel Switching with Respect to Input Voltage Level
Rev 0.0
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5.2. LED Quantity for Channels
The equation that decides the number of LEDs on each channel is shown in the table below.
Number of LEDs for Channel = VCH÷VF(LED)
Channels
VCH range
CH1
3 ~ (VAC * 1.414 – V sum ofCH2~4 Max(V))
CH2
3 ~ 120V
CH3
3 ~ 120V
CH4
3 ~ 120V
VAC input x √2 = VCH1+VCH2+VCH3+VCH4
85V < VAC input < 265V
AC input Operating Voltage Range = (VCH1+VCH2+VCH3+VCH4 )±15V
Table5. Total LED Operation
Figure18. Example of LED Quantity for AC Input Voltage(VF=3.0V)
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5.3. VCOMP (VAC Compensation)
If there is some amount of change in input voltage within a range of ±10%, then there is going to be
same amount change in input power, because internal reference voltage is fixed no matter what
input voltage is.
In order to compensate the phenomena, the peak value of input voltage is sampled and compared
to the standard input voltage. Then the system modulates level of channel ref voltage by the
amount of the deviation of peak and standard input voltage in order to compensate input power.
-
-
-
After
110V
110V
100V
100V
100 V
120 V
Before
ILED@110V
-
ILED@100V, 110V
ILED@100V
120V
120V
110V
110V
ILED@110V
ILED@110V, 120V
ILED@120V
Figure19. VCOMP Power Compensation Waveform
12.28%
9.64%
After
Before
Figure20. VCOMP Power Compensation Graph
Rev 0.0
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AC Direct LED Lighting Driver IC
LED Power
AN-SW5903A
AC input
Before
After
Compensation rate
Min. LED Power [W]
110V  100V
8.3
9.1
9.64 %
Max. LED Power [W]
110V  120V
11.4
10
12.28 %
Table6. Power Compensation for AC Input Voltage
5.4. OTP (Over Temperature Protection)
OTP protects the IC by shutting down all channels when the Junction temperature of IC rises above
specific temperature limit (typ. 150℃).
Rev 0.0
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6. Packaging Information
QFN, 20 pins
Figure21. Package Dimensions
Rev 0.0
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