Inter
national
J
our
nal
of
Electrical
and
Computer
Engineering
(IJECE)
V
ol.
6,
No.
3,
June
2016,
pp.
1332
–
1343
ISSN:
2088-8708,
DOI:
10.11591/ijece.v6i3.9528
1332
I
ns
t
it
u
t
e
o
f
A
d
v
a
nce
d
Eng
ine
e
r
i
ng
a
nd
S
cie
nce
w
w
w
.
i
a
e
s
j
o
u
r
n
a
l
.
c
o
m
The
Effects
of
Spr
ead
Spectrum
T
echniques
in
Mitigating
Conducted
EMI
to
LED
Luminance
Mohammad
Y
anuar
Hariyawan
*,**
,
Risanuri
Hidayat
*
,
and
Eka
Firmansyah
*
*
Department
of
Electrical
Engineering
and
Information
T
echnology
,
Uni
v
ersitas
Gadjah
Mada
**
Department
of
Electrical
Engineering,
Politeknik
Calte
x
Riau
Article
Inf
o
Article
history:
Recei
v
ed
No
v
30,
2015
Re
vised
Mar
7,
2016
Accepted
Mar
21,
2016
K
eyw
ord:
EMI
LED
dri
v
er
spread
spectrum
mitig
ate
ABSTRA
CT
Rapid
v
oltage
and
current
changes
i
n
recently
ubiquitous
LED
dri
v
er
ha
v
e
a
potenc
y
to
inter
-
fere
other
de
vices.
Some
solutions
with
speci
al
con
v
erter
design,
component
design,
EMI
filter
,
and
spread-spectrum
techniques
ha
v
e
been
proposed.
Due
to
cost-size-weight
con-
straints,
the
spread-spectrum
technique
seems
to
be
a
potential
candidate
in
alle
viating
EMI
problem
i
n
LED
applica
tion.
In
this
paper
,
the
ef
fecti
v
eness
of
conducted
EMI
suppression
performance
of
the
spread-spectrum
technique
is
e
v
aluated.
Spread
spectrum
techniques
applied
by
gi
ving
disturbance
to
the
LED
dri
v
er
system
with
three
profile
signals,
filtered
square,
triangular
,
and
sine
disturbance
signal
to
the
switching
pattern
of
a
b
uck
LED
dri
v
er
topology
.
From
the
e
xperiment
results,
472.5
kHz
triangular
and
525
kHz
sine
signal
can
reduce
EMI
by
42
dB
while
the
filtered
square
signal
can
reduce
EMI
40.70
dB
compared
to
fundamental
constant-fre
quenc
y
reference
669
kHz.
The
filtered
square
signal
can
re-
duce
the
a
v
erage
po
wer
le
v
el
better
than
other
signal
disturbance
of
5.852618
dB
V
.
LED
luminance
decreases
when
the
spread-spectrum
technique
is
applied
to
the
system.
Copyright
c
2016
Institute
of
Advanced
Engineering
and
Science
.
All
rights
r
eserved.
Corresponding
A
uthor:
Mohammad
Y
anuar
Hariya
w
an
Department
of
Electrical
Engineering
and
Information
T
echnology
,
Uni
v
ersitas
Gadjah
Mada
Jalan
Grafika
No.
2,
Y
ogyakarta,
55281
Indonesia
+62
811760655
yanuar@pcr
.ac.id
1.
INTR
ODUCTION
No
w
adays,
light
emitting
diodes
(LEDs)
are
becoming
increasingly
popular
use
in
v
arious
applications,
such
as
indoor
and
outdoor
lighting,
street
lighting,
decorations,
and
v
ehicle
applications.
The
main
purpose
of
LED
lights
is
ener
gy
sa
ving
due
to
the
use
of
lo
w
po
wer
,
high
ef
ficienc
y
and
lo
w
maintenance
[1]-[4].
In
addition,
it
is
durable,
en
vironmentally
friendly
,
and
no
toxic
substances
composition
compared
to
other
lighting
types
[5]-[10].
T
o
achie
v
e
high
ef
ficienc
y
in
ener
gy
transfer
,
switched-mode
po
wer
supply
(SMPS)
topology
is
applied,
such
as
b
uck,
boost,
flyback,
cuk
dan
b
uck-boost
[11]-[22].
In
addition,
the
SMPS
is
widely
applied
due
to
the
benefits
of
fered
in
terms
of
size,
weight,
cost
and
performance.
SM
PS
is
usually
implemented
using
pulse
width
modulation
(PWM).
PWM
operates
at
a
constant
frequenc
y
.
The
weakness
of
this
system
is
the
fundamental
and
ha
rmonic
frequencies
emitted
through
conducted
and
radiated
mechanism.
This
emission
is
called
electromagnetic
interference
(EMI).
As
a
result,
the
potential
con
v
erter
does
not
meet
the
standards
of
electromagnetic
compatibility
(EMC)
[11],[14][23],[24].
SMPS
has
a
periodic
switching
pattern,
i.e.
EMI
spectrum
which
consists
of
the
fundamental
and
harmonic
frequencies
with
significant
amplitudes
up
to
the
20th
harmonic
[25].
This
condition
could
probably
pass
the
limit
set
by
the
conducted
EMI
CISPR
22
Class
B
standards.
Some
solutions
are
used
to
reduce
EMI
issues
in
LED
dri
v
ers,
including
the
con
v
erter
designs
[12],[19],[18],[22],[26]-[32],
components
design
[17],[33]-[35],
EMI
filter
[30],[36]
and
spread-spectrum
techniques
[6],
[11],
[14],
[23],
[37]-[39].
Of
all
these
solutions,
the
spread-spectrum
technique
is
a
solution
that
is
ine
xpensi
v
e
and
ef
ficient
in
mitig
ating
EMI.
In
this
paper
,
conducted
EMI
mitig
ation
i
s
done
by
applying
a
spread-spectrum
techniques
in
b
uck
topology
LED
dri
v
er
and
observing
its
ef
fect
on
the
LED
luminance.
Spread
spectrum
techniques
implemented
by
gi
ving
disturbance
to
the
system
with
3
profile
of
w
a
v
eform
signals,
fil
tered
square,
triangle
and
sinusoidal
w
a
v
eform
signals.
J
ournal
Homepage:
http://iaesjournal.com/online/inde
x.php/IJECE
I
ns
t
it
u
t
e
o
f
A
d
v
a
nce
d
Eng
ine
e
r
i
ng
a
nd
S
cie
nce
w
w
w
.
i
a
e
s
j
o
u
r
n
a
l
.
c
o
m
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
1333
Ef
fecti
v
eness
in
mitig
ating
the
ef
fects
of
the
conducted
EMI
and
LED
luminance
will
be
studied.
This
will
ensure
electromagnetic
compatibility
(EMC)
of
the
system.
2.
CONDUCTED
EMI
MITIGA
TION
IN
LED
DRIVER
All
the
LED
dri
v
er
ha
v
e
to
comply
with
radiation
emission,
IEC
=
EN
61000-6-3
standards,
which
limits
in
the
150
kHz
to
30
MHz
frequenc
y
range.
This
Standard
uses
the
limits
specified
by
CISPR
22
in
the
USA
and
the
European
Norm
EN55022.
Limits
gi
v
en
in
CISPR
22
and
EN55022
standard
are
intended
for
de
vices
related
to
computers
and
communications,
b
ut
this
has
been
adopted
as
a
common
limit
for
all
electronic
products,
including
the
lighting.
CISPR
22
standard
for
conducted
emissions
sho
wn
in
Figure
1.
Figure
1.
Conducted
Emission
CISPR
22
Standard
One
method
to
reduce
the
amplitude
of
the
EMI
is
to
use
a
v
ariable
switching
frequenc
y
,
which
is
kno
wn
as
spread-spectrum
techniques
[40].
In
this
case,
the
switching
con
v
ert
er
is
not
w
orking
at
a
fix
ed
frequenc
y
.
Frequenc
y
will
v
ary
within
a
small
range,
up
and
do
wn
of
the
v
alue
of
the
base,
it
will
pro
vide
a
wider
spectrum
with
a
lo
wer
amplitude.
It
is
intended
to
spread
a
centralized
ener
gy
into
the
frequenc
y
band,
as
sho
wn
in
Figure
2.
Figure
2.
Representation
of
Signal
Clock
Frequenc
y
with
and
without
Spread-Spectrum
Modulation
Spread
spectrum
technique
is
used
in
man
y
applications,
class
D
amplifier
[5],
[6],
the
microprocessor
clock
generator
[7]-[9],
electronic
ballasts
[10]
and
on
the
LCD
display
panel
[11].
Spread
spectrum
technique
is
also
adopted
in
communication
protocols
such
as
serial
A
T
A
[12].
In
the
dc/dc
switching
con
v
erter
,
this
technique
has
been
widely
studied
since
1994
[13]
emissions
in
the
common
mode
and
dif
ferential
mode,
both
of
which
can
be
reduced
with
frequenc
y
modulation.
The
research
that
addresses
EMI
mitig
ation
techniques
in
LED
dri
v
er
using
spread-spectrum
method
w
as
first
proposed
in
2008
[37].
In
this
study
,
Gated
PWM
(GPWM)
proposed,
distrib
uted
switching
pulses
resulting
in
lo
wer
EMI
than
the
linear
PWM.
GPWM
tak
e
adv
antage
of
the
binary
PWM
(BPWM):
data
flo
w
control
and
the
required
lo
w
amount
of
b
uf
fer
memory
in
processing
and
storage.
LED
dimming
t
echnique,
GPWM
recomended
for
LED
video
display
where
it
tak
es
a
high-le
v
el
grayscale.
This
technique
of
f
ers
impro
v
ed
gray
le
v
el
compared
with
PWM
and
BPWM.
Frequenc
y
jitter
technique,
proposed
to
solv
e
EMI
problems
in
PWM
dimming
LED
dri
v
er
module
[6].
PWM
dimming
circuit
consists
of
a
selector
and
comparator
.
T
o
spread
the
switching
frequenc
y
in
a
specific
band,
blocks
of
frequenc
y
jittering
are
used.
Reference
v
oltage
in
lar
ge
numbers
is
needed
to
obtain
dif
ferent
frequencies
from
which
each
frequenc
y
will
represent
specific
v
alue.
Simple
resistance
di
vider
is
used
to
obtain
dif
ferent
reference
T
itle
of
manuscript
is
short
and
clear
,
implies
r
esear
c
h
r
esults
(F
ir
st
A
uthor)
Evaluation Warning : The document was created with Spire.PDF for Python.
1334
ISSN:
2088-8708
v
oltages.
A
technique
kno
wn
as
spread-spectrum
frequenc
y
modulation
(SSFM)
is
proposed
to
mitig
ate
EMI
[11].
In
this
technique,
the
switching
frequenc
y
will
swing
in
a
narro
w
range,
up
and
do
wn
of
the
fundamental
frequenc
y
.
This
technique
produces
a
wider
spect
rum
with
a
lo
wer
amplitude.
Operating
frequenc
y
will
be
stretched
up
to
2
4
%
up
and
do
wn
of
the
fundamental
frequenc
y
.
Frequenc
y
can
not
be
v
aried
too
much,
because
it
will
af
fect
the
a
v
erage
current
through
the
LED.
Acti
v
e
EMI
mitig
ation
scheme
using
pseudorandom
frequenc
y
modulation
is
proposed
to
minimize
EMI
[14].
It
is
dif
ferent
from
most
of
the
techniques
that
use
DSP
or
MCU,
the
proposed
mitig
ation
technique
uses
10
th
order
linear
feedback
shift
re
gister
(LFSR)
to
generate
pseudo-random
v
ectors
that
are
used
to
control
the
PWM,
which
four
out
of
ten
bits
of
LFSR
is
used
to
cont
rol
the
PWM.
In-depth
analysis
has
been
carried
out
and
sho
wed
promising
results.
0.35
m
system
is
designed
in
TSMC
CMOS
process
and
meet
EMI
standards
for
LED
dri
v
er
without
sacrificing
stability
and
ef
ficienc
y
.
The
measurement
results
sho
w
that
the
proposed
timing
can
reduce
EMI
by
14
dB
while
maintaining
a
constant
current
of
120
mA.
Probabilistic
PWM
(PPWM)
pulse
generation
using
modified
linear
feedback
shift
re
gister
(LFSR)
is
pro-
posed
to
address
EMI
[38].
The
emer
gence
frequenc
y
,
peak
v
alue,
and
v
ariety
of
incoming
currents
can
be
reduced
by
PPWM
control,
which
is
stochastic
choose
PWM
pulse
timing
and
control
LEDs
connected
serially
,
can
ef
fecti
v
ely
eliminate
the
problem
of
temperature
and
EMI.
The
test
results
sho
wed
that
PPWM
dimming
can
reduce
the
a
v
erage
v
alue
of
the
peak
inflo
ws
of
up
to
2-5
%
and
a
v
ariation
of
up
to
35
%,
with
the
cost
of
the
hardw
are
that
is
af
fordable.
Chaos-based
pulse
width
modulation
(CPWM)
is
used
to
suppress
harmonics
in
the
half-bridge
resonant
(HBR)
LED
dri
v
ers
[23].
CPWM
proposed
to
suppress
EMI
in
high-po
wer
LED
dri
v
er
.
CPWM
circuit
is
used
to
generate
chaos
analog
circuits
by
adopting
Chua
oscillator
.
By
using
an
e
xternal
chaotic
signal
to
the
PWM
control
circuit
in
the
po
wer
supply
half-bridge
resonant
(HBR)
can
ef
fecti
v
ely
suppress
EMI.
The
most
substantial
reduction
of
EMI
by
24
dB,
is
obtained
when
using
a
switching
frequenc
y
of
565.56
kHz
at
R14
=
100k
.
3.
RESEARCH
METHOD
The
core
of
the
e
xperimental
setup
is
the
LM3409
LED
dri
v
er
demonstration
board
b
uck
topology
.
The
e
v
aluation
board
pro
vides
interference
to
the
switching
system.
The
e
v
aluation
board
is
designed
to
dri
v
e
4
LEDs
(V
O
=
15V)
at
a
v
erage
maximum
current
LED
(ILED=1A)
of
the
DC
input
v
oltage
(VIN=24V).
Switching
frequenc
y
(FSW=525
kHz)
is
the
frequenc
y
to
be
achie
v
ed
for
the
nominal
point
of
operat
ion,
though
FSW
v
aries
throughout
the
operating
range.
LM3409
demonstration
board
schematic
con
v
erter
sho
wn
in
Figure
3,
can
a
ccept
input
v
oltages
with
range
6V
to
42V
.
If
the
input
v
oltage
drop
belo
w
the
LED
string
v
oltage,
con
v
erter
drop
out
and
ideally
V
O
=
VIN.
Figure
3.
Schematic
LM3409
LED
Dri
v
er
Buck
Con
v
erter
Ev
aluation
Board
T
w
o
v
ariations
on
the
LED
dri
v
er
system
testing
w
as
conducted
to
observ
e
ef
fecti
v
eness
of
the
system
in
reducing
EMI,
the
LED
dri
v
er
in
normal
operation
and
LED
dri
v
er
with
three
w
a
v
e
forms
as
signal
disturbance
as
sho
wn
in
Figure
4.
Con
v
erter
set
up
testing
is
done
using
standard
CISPR
22.
Measurements
were
performed
in
125
kHz
-
925
kHz
frequenc
y
range.
The
purpose
of
this
arrangement
is
to
create
a
test
en
vironment
that
is
uniform
to
clarify
the
ef
fect
of
the
method
chosen.
By
using
the
method
and
arrangement,
it
is
e
xpected
the
dif
ference
between
a
constant
switching
frequenc
y
and
spreading
switching
frequenc
y
can
be
distinguished
easily
.
IJECE
V
ol.
6,
No.
3,
June
2016:
1332
–
1343
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
2088-8708
1335
Figure
4.
Three
Profiles
Signal
Interference
3.1.
Constant-Fr
equency
Refer
ence
Con
v
erter
The
e
xperimental
setup
is
carried
out
under
normal
conditions
without
an
y
disturbance
on
IADJ
pin
with
an
input
v
oltage
of
24
v
ol
ts.
In
the
IC
LM3409,
there
is
IADJ
pin
connected
to
R5
potentiometer
(250
K
)
(Figure
3).
IADJ
pin
has
function
to
adjust
the
brightness
of
LED
lights
by
pro
viding
output
v
oltage
and
current
v
ariations.
Block
diagram
of
the
test
can
be
seen
in
Figure
5.
The
parameters
measured
in
this
test
is
a
spectrum
EMI
and
LED
luminance
changes,
when
IADJ
change
from
0.01
V
to
1.2
V
.
Figure
5.
Block
Diagram
of
Performance
T
esting
Constant-Frequenc
y
Reference
LED
Dri
v
er
3.2.
LED
Dri
v
er
P
erf
ormance
T
est
by
F
eeding
Disturbance
to
IADC
T
est
P
oint
This
e
xperiment
step
is
done
with
the
conditions
pro
viding
disturbances
in
IADJ
pin
when
R5
potentiometer
set
in
minimum
conditions
v
alue.
These
disturbance
signals
comes
in
three
types
of
w
a
v
eform,
sine,
filtered
square,
and
the
triangle
that
generates
by
function
generator
.
Disturbance
w
a
v
eform
signal
has
a
v
oltage
of
0-1
Vpp
with
the
frequenc
y
of
10
%
of
the
w
orking
frequenc
y
of
525
kHz
LED
dri
v
er
.
The
signal
frequenc
y
will
be
set
in
472.5
kHz,
498.75
kHz,
525
kHz,
551.25
kHz
and
577.5
kHz.
Block
diagram
of
the
current
testing
system
is
gi
v
en
i
n
the
form
of
three
w
a
v
eform
disturbance
signals
can
be
seen
in
Figure
6.
4.
RESUL
T
AND
AN
AL
YSIS
4.1.
LED
Dri
v
er
P
erf
ormance
T
est
in
Constant-Fr
equency
Refer
ence
The
EMI
generated
on
e
v
ery
change
in
the
v
alue
of
IADJ
can
be
seen
in
Figure
7,
it
can
be
seen
that
when
R5
v
alue
change,
IADJ
v
oltage
and
w
orking
frequenc
y
also
changes.
When
com
pared
with
the
CISPR
22
Class
B,
the
le
v
el
of
po
wer
generated
at
eac
h
operating
frequenc
y
e
xceeding
the
limit
set
by
CISPR
22
Class
B.
The
a
v
erage
po
wer
le
v
els
generated
for
a
ll
amplitude
v
alue
is
about
39.834
dB
V
.
In
the
563
kHz-683
KHz
frequenc
y
range,
generated
po
wer
le
v
els
abo
v
e
the
maximum
v
alue
set
by
CISPR.
The
highest
po
wer
le
v
el
e
xceeds
t
h
e
standard,
occurs
when
the
test
point
IADJ
gi
v
en
v
oltage
0.2Vpp
at
a
frequenc
y
of
627
KHz.
When
compared
to
standard
CISPR
ha
ving
a
dif
ference
of
15.9
dB
V
.
When
IADJ
pin
gi
v
en
dif
ferent
input
v
oltages,
LED
luminance
will
change,
can
be
seen
in
Figure
8.
The
LED
luminance
will
increase
when
IADJ
changed
from
0.023
mV
to
849
mV
,
after
which
the
849
mV
to
1200
mV
decreased
LED
luminance
.
T
itle
of
manuscript
is
short
and
clear
,
implies
r
esear
c
h
r
esults
(F
ir
st
A
uthor)
Evaluation Warning : The document was created with Spire.PDF for Python.
1336
ISSN:
2088-8708
Figure
6.
Block
Diagram
of
Performance
T
esting
LED
Dri
v
er
by
Gi
ving
Disturbance
to
IADJ
Figure
7.
LED
Luminance
Vs
IADJ
Figure
8.
LED
Luminance
Vs
IADJ
4.2.
LED
Dri
v
er
P
erf
ormance
by
F
eeding
Disturbance
on
IADJ
4.2.1.
Filter
ed
Squar
e
Pr
ofile
Signal
Disturbance
When
gi
v
en
filtered
square
profile
signal
disturbance
on
the
IADJ
pin,
the
signal
le
v
el
is
obtained
as
sho
wn
in
Figure
9.
In
the
frequenc
y
range
from
563
kHz-683
kHz,
there
is
a
decrease
in
po
wer
le
v
el
when
gi
v
en
filtered
IJECE
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1337
square
signal
disturbance
on
IADJ
pin.
The
a
v
erage
po
wer
le
v
el
generated
by
the
fi
v
e
frequenc
y
is
about
28.6
dB
V
.
When
compared
with
the
po
wer
le
v
el
of
the
reference
signal
po
wer
le
v
el
there
is
a
reduction
about
5.8
dB
V
.
The
most
significant
reduction
of
po
wer
le
v
el
occurs
at
525
kHz,
its
about
41.90
dB,
this
v
alue
is
quite
significant
if
compared
with
pre
vious
research
[14],[23].
The
o
v
erall
le
v
el
of
po
wer
generated
by
the
filtered
square
signal
belo
w
the
established
standards
CISPR
22
Class
B.
Meanwhile
the
luminance
produced
by
the
LED
when
gi
v
en
the
disruption
of
filtered
square
w
a
v
eform
is
about
146
lux.
The
switching
fr
equenc
y
v
aries
between
292-675
kHz
as
sho
wn
in
Figure
10.
Figure
9.
Po
wer
Le
v
els
Distrib
ution
when
Gi
v
en
Filtered
Square
Signal
Disturbance
Figure
10.
Switching
Frequenc
y
when
Gi
v
en
Filtered
Square
Signal
Disturbance
4.2.2.
T
riangle
W
a
v
e
Signal
Disturbance
When
gi
v
en
triangular
w
a
v
eform
with
frequenc
y
range
of
563
kHz-683
kHz
at
IADJ
point
there
is
po
wer
le
v
el
reduction
as
sho
wn
in
Figure
11.
The
a
v
erage
po
wer
le
v
el
generated
by
the
fi
v
e
frequenc
y
is
about
29.6
dB
V
.
T
itle
of
manuscript
is
short
and
clear
,
implies
r
esear
c
h
r
esults
(F
ir
st
A
uthor)
Evaluation Warning : The document was created with Spire.PDF for Python.
1338
ISSN:
2088-8708
When
compared
with
the
po
wer
le
v
el
of
the
reference
po
wer
le
v
el
signal
there
is
a
decrease
of
4.8
dB
V
.
The
most
significant
reduction
of
po
wer
le
v
el
occurs
when
system
is
gi
v
en
498.75
kHz
triangle
signal,
its
about
40.60
dB
this
v
alue
is
also
quite
significant
if
compared
with
pre
vious
research
[14],[23].
As
is
the
case
when
the
system
is
gi
v
en
a
filtered
square
w
a
v
eform,
the
o
v
erall
le
v
el
of
po
wer
generated
by
triangular
w
a
v
eform
resulting
disturbance
le
v
els
belo
w
established
standards
CISPR
22
Class
B.
Whereas
the
luminance
produced
by
the
LED
current
when
gi
v
en
triangular
w
a
v
eform
is
about
146
lux.
The
switching
frequenc
y
v
aries
between
281-683
kHz
as
sho
wn
in
Figure
12.
Figure
11.
Po
wer
Le
v
els
Distrib
ution
when
Gi
v
en
T
riangle
Signal
Disturbance
Figure
12.
Switching
Frequenc
y
when
Gi
v
en
T
riangle
Signal
Disturbance
4.2.3.
Sine
W
a
v
e
Signal
Disturbance
When
gi
v
en
sine
w
a
v
eform
disturbances
on
IADJ
point
as
sho
wn
in
Figure
14,
in
the
563
kHz-683
kHz
frequenc
y
range,
there
is
a
decrease
in
po
wer
le
v
el.
The
a
v
erage
po
wer
le
v
el
generated
by
the
fi
v
e
frequenc
y
is
about
29.5
dB
V
.
When
compared
with
the
po
wer
le
v
el
reference
signal
there
is
a
decrease
in
the
po
wer
le
v
el
about
4.9
dB
V
.
The
most
significant
reduction
of
po
wer
le
v
el
occurs
when
the
frequenc
y
of
525
kHz,
is
about
42
dB,
this
v
alue
is
also
quite
significant
if
compared
with
pre
vious
research
[14],[23].
As
is
the
case
when
the
system
is
gi
v
en
a
signal
disturbance
filtered
square
and
triangles
w
a
v
eform,
the
o
v
erall
le
v
el
of
po
wer
generat
ed
by
the
sine
w
a
v
eform,
the
resulting
disturbance
le
v
els
belo
w
established
standards
CISPR
22
Class
B.
Whereas
the
luminance
produced
by
the
IJECE
V
ol.
6,
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3,
June
2016:
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1343
Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE
ISSN:
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1339
LED
current
is
gi
v
en
filtered
square
w
a
v
eform
is
about
139
lux.
The
switching
frequenc
y
v
aries
between
290-657kHz
as
sho
wn
in
Figure
13.
Figure
13.
Switching
Frequenc
y
when
Gi
v
en
Sine
Signal
Disturbance
Figure
14.
Po
wer
Le
v
els
when
Gi
v
en
Sine
Signal
Disturbance
When
the
system
is
gi
v
en
three
periodic
w
a
v
eforms
at
the
point
IADJ
with
a
frequenc
y
of
525
kHz
and
com-
pared
with
a
reference
signal
when
the
minimum
dimming,
filtered
square
has
a
better
performance
when
compared
with
other
w
a
v
eform
to
suppress
EMI,
as
sho
wn
in
Figure
15.
The
a
v
erage
le
v
el
of
the
po
wer
generated
by
the
third
signal
is
equal
to
29.26143
dB
V
.
The
a
v
erage
po
wer
le
v
el
of
squared
filtered
w
a
v
eform
has
the
smallest
v
alue
when
compared
with
others
w
a
v
eform
is
about
28.56309
dB
V
.
The
a
v
erage
reduction
po
wer
le
v
el
of
the
third
signal
at
5.154281
dB
V
,
and
filtered
square
w
a
v
eform
ha
v
e
better
po
wer
le
v
el
reduction
is
about
5.852618
dB
V
.
V
.
The
a
v
erage
po
wer
le
v
el
reduction
of
the
third
signal
at
5.154281
dB
V
,
and
filtered
square
w
a
v
eform
ha
v
e
better
po
wer
le
v
el
reduction
is
about
5.852618
dB
V
.
The
most
significant
reduction
of
po
wer
le
v
el
occurs
when
system
gi
v
en
525
kHz
triangle
disturbance,
is
about
42
dB
reduction,
this
v
alue
is
quite
s
ignificant
if
compared
with
pre
vious
research
[14],[23]
which
use
non-periodic
signal
to
mitig
ate
EMI.
Measurement
results
sho
wed
t
hat
the
proposed
mitig
ation
scheme
using
10
th
order
LFSR
to
generate
pseudo-random
v
ectors
can
reduce
EMI
only
14
dB
[14].
CPWM
which
adopt
Chua
oscillator
to
generate
chaotic
signal
can
reduce
EMI
only
24
dB
[23].
When
the
pin
VDJ
gi
v
en
disturbance,
LED
luminance
decreases
compared
with
LED
dri
v
er
w
orks
in
constant-
frequenc
y
reference.
When
the
system
w
orks
on
a
constant-frequenc
y
reference
with
a
v
oltage
of
0.07
to
1,129
mVpp,
T
itle
of
manuscript
is
short
and
clear
,
implies
r
esear
c
h
r
esults
(F
ir
st
A
uthor)
Evaluation Warning : The document was created with Spire.PDF for Python.
1340
ISSN:
2088-8708
lux
v
aries
between
178-2,960
lux,
as
in
Figure
8.
LED
luminance
decrease
significantly
,
less
than
about
2814
lux.As
filtered
square
and
traingle
disturbance
signal
gi
v
en
at
LED
dri
v
er
,luminance
LED
system
is
about
146
lux.
whereas
sinusoidal
signals
produce
luminance
139
lux,
as
sho
wn
in
Figure
16.
Figure
15.
Comparison
of
Po
wer
Le
v
el
Distrib
ution
3
Dif
ferent
Signals
Disturbance
at
525
kHz
Figure
16.
LED
Luminance
when
Gi
v
en
Disturbance
5.
CONCLUSION
The
e
xperiment
results
confirms
that
the
spread-spectrum
technique
is
ef
fecti
v
e
in
mitig
ating
conducted
EMI
generated
by
the
LED
dri
v
er
b
ut
sacrificing
LED
luminance.
The
results
sho
w
that
when
the
system
is
gi
v
en
filtered
square,
triangular
and
sine
w
a
v
eform
disturbance
signal
can
mitig
ate
EMI
generated
by
the
LED
dri
v
er
.
From
the
test
results,
525
kHz
sine
signal
is
the
most
ef
fici
ent
signal
disturbance
to
mitig
ate
EMI
by
42
dB
then
follo
wed
by
filtered
square
signal
that
can
mitig
ate
EMI
by
41.9
dB.
The
lo
west
a
v
erage
po
wer
le
v
el
is
achie
v
ed
by
filtered
square
signal
is
about
36.447
dB
.
The
filtered
square
signal
m
ost
significant
can
reduce
the
a
v
erage
po
wer
l
e
v
el
about
3.27
dB
V
.
By
pro
viding
three
types
of
signal
disturbance
on
the
LED
dri
v
er
system
resulting
in
decreased
le
v
els
of
LED
luminance.
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T
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esear
c
h
r
esults
(F
ir
st
A
uthor)
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