Datasheet

UEI25 Series
Single Output Isolated 25-Watt DC/DC Converters
MDC_UEI25W.B09 Page 22 of 24
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Emissions Performance
Murata Power Solutions measures its products for radio frequency emissions
against the EN 55022 and CISPR 22 standards. Passive resistance loads are
employed and the output is set to the maximum voltage. If you set up your
own emissions testing, make sure the output load is rated at continuous power
while doing the tests.
The recommended external input and output capacitors (if required) are
included. Please refer to the fundamental switching frequency. All of this
information is listed in the Product Specifi cations. An external discrete fi lter is
installed and the circuit diagram is shown below.
[1] Conducted Emissions Parts List
[2] Conducted Emissions Test Equipment Used

Rohde & Schwarz EMI Test Receiver (9KHz – 1000MHz) ESPC

Rohde & Schwarz Software ESPC-1 Ver. 2.20

OHMITE 25W – 1 Ohm resistor combinations

DC Source Programmable DC Power Supply Model 62012P-100-50
[3] Conducted Emissions Test Results
[4] Layout Recommendations
Most applications can use the fi ltering which is already installed inside the
converter or with the addition of the recommended external capacitors. For
greater emissions suppression, consider additional fi lter components and/or
shielding. Emissions performance will depend on the user’s PC board layout,
the chassis shielding environment and choice of external components.
Since many factors affect both the amplitude and spectra of emissions, we
recommend using an engineer who is experienced at emissions suppression.
Reference Part Number Description Vendor
L1 PE-62913 1mH, 6A Pulse
L2 NC 4.7uH, 3.6A Murata
C1, C2 VZ Series Electrolytic Capacitor 22ufd, 100V Panasonic
C3 VZ Series Qty 2 - Electrolytic Capacitor 22ufd, 100V Panasonic
C4, C5 Unknown 3.3nF, 1500V Unknown
C6 VZ Series Electrolytic Capacitor 22ufd, 100V Panasonic
DC Source
Test Card
UUT
V+
V- Vin- Vout-
Vin+
Resistive Load
inside a metal
container
Vout+
Black
C1
L1
C2
L2
C3 C6
C4
C5
Resistive Load
Figure 7. Conducted Emissions Test Circuit
Graph 1. Conducted emissions performance with fi lter, Negative Line, CISPR 22, Class B,
full load, for UEI25-033-D48PM-C
dBµV
100
0
10
20
30
40
50
60
70
80
90
MHz
30.00.15 1.0 10.0
QP AV
Graph 3. Conducted emissions performance without fi lter, Negative Line, CISPR 22, Class
B, full load, for UEI25-050-D48NM-C
dBµV
100
0
10
20
30
40
50
60
70
80
90
MHz
30.00.15 1.0 10.0
QP Average
Graph 2. Conducted emissions performance with fi lter, Negative Line, CISPR 22, Class B,
full load, for UEI25-050-D48NM-C
dBµV
100
0
10
20
30
40
50
60
70
80
90
MHz
30.00.15 1.0 10.0
QP
AV
Graph 4. Conducted emissions performance with fi lter, Negative Line, CISPR 22, Class B,
full load, for UEI25-120-D48P-C
dBµV
100
0
10
20
30
40
50
60
70
80
90
MHz
30.00.15 1.0 10.0
QP AV