dm00051702

DN0002
Design note
10W offline LED driver based on VIPER27
Designs from our labs describe tested circuit designs from ST labs which provide optimized solutions
for specific applications. For more information or support, visit www.st.com
By Luigi Galioto
Main components
VIPER27
Offline high voltage converter
SEA05
Advanced constant voltage and constant current controller
Specification
10W LED driver
Wide input voltage range: 88Vac to 265Vac
300mA LED current
Isolated SMPS
Short circuit protection
Circuit description
The use of LEDs in lighting applications is becoming increasingly popular due to: rapid
improvements in lighting efficiency, longer life, higher reliability and overall cost
effectiveness.
This converter is a simple example of an offline
isolated LED application (10W).
The LEDs are driven by the VIPER27 high
voltage converter. The secondary side is
managed by the SEA05 advanced CC/CV
controller.
Excellent results in terms of current control
precision (±3%) and efficiency performance
(η>80%), combined with the compact form factor
which can fit in existing bulb housing, are key
benefits.
May 2012
DN0002 Rev 1
1/6
www.st.com
Figure 1. Circuit diagram
May 2012
DN0002 Rev 1
2/6
www.st.com
Measurement results
The board was tested in terms of efficiency, output voltage limitation and LED current
regulation for a wide input voltage range. Table 1 shows the results obtained for a 30
minute test. High efficiency and excellent LED current regulation were obtained.
Table 1.
Experimental results
Start up tests with Vin=110V and Vin=230V were also reported in full load and no load
conditions. The behavior of Vout, Vcc and Iout were monitored.
Figure 2. Test results: start up sequence at full load condition
May 2012
DN0002 Rev 1
3/6
www.st.com
Figure 3. Test results: start up sequence at no load condition
The VIPER27 is protected against short circuits on the secondary rectifier and secondary
winding, and a hard-saturation of the flyback transformer. Tests were conducted where the
board was subject to short circuits and it protected itself well. The behavior shown in figure
3 illustrates the typical low frequency intermittent operation (hiccup- mode operation).
May 2012
DN0002 Rev 1
4/6
www.st.com
Figure 4. Test results: short circuit condition
Support material
Related design support material
EVLVIP27-7WLED: 3.5W to 7W high power factor offline LED driver based on VIPer devices
Gerber files for 10W LED driver http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_DIAGRAM/PCB_LAYO
UT/10wled_pcb_layout.zip
Documentation
Magnetica, Switch Mode Transformer 10W 55kHz 980uH – see attachment at end of document.
www.magnetica.eu Code 1715.0032
AN3212: 3.5W to 7W high power factor offline LED driver based on VIPer devices
Revision history
Date
15-May-2012
May 2012
Version
1
Changes
Initial release
DN0002 Rev 1
5/6
www.st.com
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May 2012
DN0002 Rev 1
6/6
www.st.com
STP 21
Code: 1715.0032
Product Technical Specification
Product: Switch Mode Transformer 10W 55kHz 980uH
Customer: STMICROELECTRONICS
Date : 27.04.12
Customer code:
Revision: 01
Page 1 of 2
TYPICAL APPLICATION
TECHNICAL DATA
TRANSFORMER FOR FLYBACK POWER SUPPLIES IN INDUCTANCE
APPLICATIONS WITH CONTROLLER VIPER28
(MEASURE 1KHZ, TA 20°C)
PIN 3-1
CIRCUIT DIAGRAM
PIN 4-5
PIN 8-7
980 uH ±15%
39 uH ±15%
179 uH ±15%
RESISTANCE
(MEASURE D.C, TA 20°C)
3-1
4-5
PIN 8-7
1.22 MAX
280 m MAX
250 m MAX
PIN
PIN
1
TRANSFORMER RATIO
8
(MEASURE 10KHZ, TA 20°C)
PIN
PIN
3-1
3-1
4-5
8-7
5 5%
2.36 5%
2.5 % NOM
LEAKAGE INDUCTANCE
(MEASURE 3-1 AND 4-5-7-8 IN S.C, F 10KHZ, TA 20°C)
14 PF NOM
PARASITIC CAPACITANCE
3
(MEASURE 3-1, F 1MHZ, TA 20°C)
4
7
0.94AP MAX
SATURATION CURRENT
(MEASURE 3-1, BSAT 0.32T, TA 20°C)
0.85 AP MAX
OPERATING CURRENT
(MEASURE 3-1, PMAX 10W ,F 55KHZ, TA 20°C)
5
55 KHZ NOM
OPERATING FREQUENCY
(PMAX 10W , TA 20°C)
-10°C +45°C
OPERATING TEMPERATURE RANGE
(PMAX 10W )
4KV
PRIMARY TO SECONDARY INSULATION
(F 50HZ,DURATION TEST 2”, TA 20°C)
27X22XH18 mm
MAXIMUM DIMENSIONS
12 g APPROX
WEIGHT
PIN DESCRIPTION
PIN(*)
PIN(*)
FUNCTION
1
2
3
4
5
PRIMARY +VB 120-400VDC
6
NOT USED
7
PRIMARY DRAIN
8
AUXILIARY
9
+15V 15mA
AUXILIARY GROUND
(*)PIN WITH THE SAME SUBSCRIPT MUST BE CONNECTED TOGETHER ON PCB
MOR&D0014-00
FUNCTION
NOT USED
SECONDARY GROUND
SECONDARY
NOT USED
+33V 300mA
Rev.00
02/09/08
MAGNETICA
Via Marcora, 20 60022 Castelfidardo (AN)
Tel +39 071 7823855
Copyright Magnetica, cannot be reproduced even partially without written authorization.
STP 21
Code: 1715.0032
Product Technical Specification
Product: Switch Mode Transformer 10W 55kHz 980uH
Customer: STMICROELECTRONICS
Date : 27.04.12
Customer code:
Revision: 01
Page 2 of 2
DIMENSIONAL DRAWING
LABEL
18 MAX
3.5 MIN
27 MAX
22 MAX
9
1
8
2
21 MAX
3
7
4
6
5
19.05
15.24
5.08
7.62
15.24
0.7 (X9),
RECOMMENDED PCB HOLE
1.1 (X9)
BOTTOM VIEW (PIN SIDE)
DIMENSIONS IN MILLIMETERS, DRAWING NOT IN SCALE
MOR&D0014-00
Rev.00
02/09/08
MAGNETICA
Via Marcora, 20 60022 Castelfidardo (AN)
Tel +39 071 7823855
Copyright Magnetica, cannot be reproduced even partially without written authorization.
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