AN4213
Application note
High-frequency ballast 2x58 W (T8 fluorescent tubes)
based on a PowerFLAT™ 5x6 package
By Santina Leo
Introduction
Fluorescent lamps are increasingly driven by electronic rather than electromagnetic ballasts
mainly because fluorescent lamps can produce around 20% more light for the same input
power when driven above 20 kHz instead of 50/60 Hz. Operation at high frequency also
eliminates both light flickering and audible noise.
This application note describes the design calculations and test results of the STEVAL-
ILB010V1demonstration board able to drive 2x58 W linear T8 fluorescent tubes. The
electronic ballast consists of two sections: a power factor correction pre-regulator (PFC),
using the L6562A, and the lamp ballast stage with the L6569. The main purpose of this
application note is to evaluate the electrical features of the new PowerFLAT™ 5x6 package
and to compare its thermal results with that of the DPAK package. The PowerFLAT™5x6
package is used in the STEVAL-ILB010V1 demonstration board shown below.
Figure 1. STEVAL-ILB010V1
AM17315v1
May 2014
DocID023984 Rev 2
1/42
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Contents
AN4213
Contents
1
2
3
System description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
PFC section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Designing a TM PFC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1
3.2
3.3
Input specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Power section design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3.3.1
3.3.2
3.3.3
3.3.4
3.3.5
3.3.6
Bridge rectifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Boost inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Power MOSFET selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Boost diode selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4
L6562A biasing circuitry (pin by pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4
DC/AC converter and lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1
4.2
Bootstrap circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Lamp requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.2.1
4.2.2
Output inductor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Lamp preheating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5
Driving optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.1
Power MOSFET circuit optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6
7
8
DC/AC converter waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Experimental results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Appendix A Board description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Appendix B Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
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AN4213
Contents
Appendix C Layout layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9
10
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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List of figures
AN4213
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.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
STEVAL-ILB010V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Boost converter circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Inductor current waveform and Power MOSFET timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
PFC electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Pin 1, 2: Feedback network implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Sense resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Multiplier setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
ZCD resistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Optimum Power MOSFET turn-on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Boost PFC section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
DC/AC converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Preheating circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Lamp output voltage timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Lamp output voltage during preheating phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Lamp output voltage during ignition phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Lamp output voltage during run-mode phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Driving network optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Turn-off detail with R
g
=220
Ω,
speed off diode and C
sn
= 47 pF @ 230 V
AC . . . . . . . . . . . . . . . 29
Turn-off detail with R
g
=220
Ω,
speed off diode and C
sn
=100 pF @ 230 V
AC . . . . . . . . . . . . . . 29
Turn-on detail with R
g
= 220
Ω,
speed off diode and C
sn
= 47 pF @ 230 V
AC. . . . . . . . . . . . . . 29
Turn-on detail with R
g
= 220
Ω,
speed off diode and C
sn
= 100 pF @ 230 V
AC . . . . . . . . . . . . . 29
Turn-off detail with R
g
=47
Ω,
no speed off diode and C
sn
= 47 pF @ 230 V
AC . . . . . . . . . . . . 30
Turn-off detail with R
g
= 47
Ω,
no speed off diode and C
sn
= 100 pF @ 230 V
AC . . . . . . . . . . 30
Turn-on detail with R
g
= 47
Ω,
no speed off diode and C
sn
= 47 pF @ 230 V
AC . . . . . . . . . . . 30
Turn-on detail with R
g
= 47
Ω,
no speed off diode and C
sn
= 100 pF @ 230 V
AC . . . . . . . . . . 30
STL13N60M2 during steady-state operation in half-bridge section @ 230 V
AC
. . . . . . . . . 32
STL13N60M2 during turn-off in half-bridge section @230V
AC
(detail) . . . . . . . . . . . . . . . . 32
STL13N60M2 during turn-on in half-bridge section @230V
AC
(detail) . . . . . . . . . . . . . . . . 33
Electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Bottom layout layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Top layout layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Silkscreen top . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Silkscreen bottom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
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AN4213
System description
1
System description
Figure 2. Block diagram
400Vdc
PFC
EMI
Filter
Co
Converter
DC/AC
AC
AM17316v1
The electronic ballast consists of two sections: a power factor correction pre-regulator
(PFC), using the L6562A, and the lamp ballast stage with the L6569.
The power factor correction section is based on the L6562A. This is a current-mode PFC
controller operating in transition mode (TM). It is especially designed for electronic lamp
ballast applications (to better understand the L6562A characteristics, refer to AN2761).
The lamp ballast stage is based on the L6569 which is a high-voltage half-bridge driver with
a built-in oscillator. The load consists of an L-C series resonant circuit with the lamps
connected across the capacitors. This topology allows operating in zero-voltage switching,
to reduce the transistor switching losses and the electromagnetic interference generated by
the output wiring of the lamp.
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