AN2961
Application note
STEVAL-ILL026V1 non-isolated 3 W offline
LED driver based on the VIPER22A-E
Introduction
This application note describes the functioning of the STEVAL-ILL026V1 non-isolated 3 W
offline LED driver power supply designed using the VIPER22A-E low power offline SMPS
primary switcher from STMicroelectronics. The circuit regulates the load current to 350 mA
and generates about 10 V. The load is composed of three high-brightness (HB) LEDs,
connected in series.
The project does not provide safety isolation between the input and output.
This document provides the power supply specification, circuit diagrams, the complete bill of
materials, and reports the results of circuit testing.
Figure 1.
STEVAL-ILL026V1 board photographs
November 2009
Doc ID 15559 Rev 1
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www.st.com
Contents
AN2961
Contents
1
2
3
4
5
6
7
8
Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Conducted emission tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Adapting the board for a 230 V input mains range . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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AN2961
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
STEVAL-ILL026V1 board photographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
STEVAL-ILL026V1 schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
VIPER22A-E startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
110 V steady state operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
LED current regulation vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Board efficiency vs. input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Conducted emissions at 230 VAC 50 Hz - line 1 peak detector . . . . . . . . . . . . . . . . . . . . . 11
Conducted emissions at 230 VAC 50 Hz - line 2 peak detector . . . . . . . . . . . . . . . . . . . . . 11
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Specification
AN2961
1
Specification
The electronic lamp ballast electrical specifications are given in the table below.
Table 1.
Specification
Input parameters
V
IN
f
line
Input voltage range
Line frequency
HB LEDs
Number
Power / current
3
3 W / 350 mA
90 to 265 V
RMS
50/60 Hz
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Doc ID 15559 Rev 1
AN2961
Bill of material
2
Bill of material
Table 2.
Type
C
C
C
C
C
C
C
D
D
D
D
L
L
Q
Q
R
R
R
R
R
R
R
U
STEVAL-ILL026V1 bill of material
Name
C1
C3
C4
C5
C6
C7
C8
D1
D2
D3
D4
L1
L2
Q1
Q2
R1
R2
R3
R4
R5
R6
R7
IC1
Value
22 µF
2.2 µF
470 nF
22 µF
470 nF
470 nF
Do not fit
39 V
STTH1R06A
Bridge
STTH1R06A
1 mH
1 mH
BC557B
BC547B
4.7 kΩ
4.7 kΩ
10 kΩ
10 kΩ
1.3
Ω
6.8 kΩ
10
Ω
VIPER22A-E
1/2 W
600 V
600 V 500 mA
600 V
Rated
50 V
450 V
50 V
50 V
50 V
400 VDC
Do not fit
Description
Electrolytic
Electrolytic
Ceramic
Electrolytic
Ceramic
Polyester EPCOS
B32561J6474K
Do not fit
Zener diode
STMicroelectronics
Rectifier bridge
STMicroelectronics
EPCOS B7818S1105J000
Coilcraft MSS1260-105KLB
PNP transistor
NPN transistor
SMD resistor 0805
SMD resistor 0805
SMD resistor 0805
SMD resistor 0805
SMD resistor 1206
SMD resistor 0805
Through hole resistor
STMicroelectronics
Doc ID 15559 Rev 1
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stm32/stm8
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