5
Rev. 0
Figure 3. DC2688A-A Demo Circuit EMI Performance in CISPR 25
Radiated Emissions Test, Peak Detector
Figure 4. DC2688A-A Demo Circuit EMI Performance in CISPR 25
Radiated Emissions Test, Average Detector
DC2688A–A DEMO BOARD
(WITH EMI FILTER INSTALLED)
14V INPUT TO 5V
BUS
OUTPUT AT 2.5A, f
SW
= 2MHz
L1 = XFL4020–222ME, C
VIN2
AND C
VIN3
POPULATED
VERTICAL POLARIZATION
PEAK DETECTOR
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
0
5
10
15
20
25
30
35
40
45
50
AMPLITUDE (dBµ
V/m)
DC2688A F03
DC2688A–A DEMO BOARD
(WITH EMI FILTER INSTALLED)
14V INPUT TO 5V
BUS
OUTPUT AT 2.5A, f
SW
= 2MHz
L1 = XFL4020–222ME, C
VIN2
AND C
VIN3
POPULATED
VERTICAL POLARIZATION
AVERAGE DETECTOR
CLASS 5 AVERAGE LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
–10
–5
0
5
10
15
20
25
30
35
40
AMPLITUDE (dBµ
V/m)
DC2688A F04
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 5. DC2688A-B Demo Circuit EMI Performance in CISPR 25
Radiated Emissions Test, Vertical Polarization
Figure 6. DC2688A-B Demo Circuit EMI Performance in CISPR 25
Radiated Emissions Test, Horizontal Polarization
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
VERTICAL POLARIZATION
PEAK DETECTOR
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
0
5
10
15
20
25
30
35
40
45
50
AMPLITUDE (dBµ
V/m)
DC2688A F05
DC2688A-B DEMO BOARD (WITH EMI FILTER INSTALLED)
14V INPUT TO 5V V
BUS
AT 2.5A, f
SW
= 2MHz, L1 = XFL4020-222ME,
CV
IN2
AND CV
IN3
POPULATED
CLASS 5 PEAK LIMIT
SPREAD SPECTRUM MODE
FIXED FREQUENCY MODE
HORIZONTAL POLARIZATION
PEAK DETECTOR
FREQUENCY (MHz)
0
100
200
300
400
500
600
700
800
900
1000
0
5
10
15
20
25
30
35
40
45
50
AMPLITUDE (dBµ
V/m)
DC2688A F06
DC2688A-B DEMO BOARD (WITH EMI FILTER INSTALLED)
14V INPUT TO 5V V
BUS
AT 2.5A, f
SW
= 2MHz, L1 = XFL4020-222ME,
CV
IN2
AND CV
IN3
POPULATED