August 2009 Doc ID 15327 Rev 2 1/43
UM0670
User manual
80 W offline LED driver with PFC
1 Introduction
The use of high power LEDs in lighting applications is becoming increasingly popular due to
rapid improvements in lighting efficiency, longer life, higher reliability and overall cost
effectiveness. Dimming functions are more easily implemented in LEDs, and they are more
robust and offer wider design flexibility compared to other light sources.
For this reason a demonstration board for driving high brightness and power LEDs has been
developed. The STEVAL-ILL013V1 demonstration board is an 80 W offline dimmable LED
driver with high power factor (PF) intended for fixed number of LEDs, the overall design of
which is described in detail in this user manual.
The LED current can be set to 350 mA, 700 mA and 1000 mA, using jumpers. Additionally,
a dimming function using a PWM (pulse width modulation) signal is implemented as well,
allowing the user to set the LED brightness from 0% up to 100%. The demonstration board
can be ordered using order code STEVAL-ILL013V1, and is shown in Figure 1.
STEVAL-ILL013V1 main features
■ 80 W LED driver
■ 350 mA, 700 mA and 1 A LED current settings
■ High efficiency (~90%)
■ Wide input voltage range: 88 to 265 VAC
■ High power factor: 0.99 for 110 VAC and 0.98 for 230 VAC
■ Universal PWM input for dimming (external board required)
■ Non-isolated SMPS
■ Brightness regulation between 0% and 100%
■ EMI filter implemented
■ EN55015 and EN61000-3-2 compliant
Figure 1. STEVAL-ILL013V1 demonstration board
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Contents UM0670
2/43 Doc ID 15327 Rev 2
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Design concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 STEVAL-ILL013V1 technical details . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Schematic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 STEVAL-ILL013V1 performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8 Dimming function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1 Output waveform measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.2 Power MOSFET turn ON and OFF time . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.3 LED current ripple reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.4 Standard EN61000-3-2 measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
9.5 EMI measurement (EN55015) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
10 Design features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10.1 Proper startup circuit design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10.2 Zero dimming design implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
11 References and related materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Appendix A Design calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
A.1 Design specifications for a modified buck convertor . . . . . . . . . . . . . . . . . 37
12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42