ADDC02808PBKV Analog Devices, ADDC02808PBKV Datasheet - Page 16

• Manufacturer Part Number: ADDC02808PBKV
• Description: 28 V/ 200 W Pulsed DC/DC Converter with Integral EMI Filter
• Manufacturer: Analog Devices

ADDC02808PB
In almost all systems the output ground of the converter is
ultimately connected to the input ground of the system. The
parasitic capacitances and inductances in this connection will
affect the common-mode voltage and the CE102 measure-
ment. In addition, the inductive impedance of this ground
connection can cause resonances, thereby affecting the perfor-
mance of the common-mode filter in the power supply.
In response to these ambiguities, the Analog Devices’ con-
verter has been tested for CE102 under a constant load and
with the output ground floating. While these measurements
are a good indication of how the converter will operate in the
final system configuration, the user should confirm CE102
testing in the final system configuration.
CE101: This test measures emissions on the input leads in the
frequency range between 30 Hz and 10 kHz. The intent of
this requirement is to ensure that the dc/dc converter does not
corrupt the power quality (allowable voltage distortion) on the
power busses present on the platform. There are several
CE101 limit curves in MIL-STD-461D. The most stringent
one app-licable for the converter is the one for submarine
applications. Figure 11 shows that the converter easily meets
this requirement (the return line measurement is similar). The
components at 60 Hz and its harmonics are a result of ripple in
the output of the power source used to supply the converter.
CE102: This test measures emissions in the frequency range
between 10 kHz and 10 MHz. The measurements are made
on both of the input leads of the converter which are con-
nected to the power source through LISNs. The intent of this
requirement in the lower frequency portion of the requirement
is to ensure that the dc/dc converter does not corrupt the
power quality (allowable voltage distortion) on the power
busses present on the platform. At higher frequencies, the
intent is to serve as a separate control from RE102 on potential
radiation from power leads which may couple into sensitive
electronic equipment.
Figure 12 shows the CE102 limit and the measurement taken
from the +V
input return line is slightly different, both comfortably meet
the MIL-STD-461D, CE102 limit.
CS101: This test measures the ability of the converter to
reject low frequency differential signals, 30 Hz to 50 kHz,
injected on the dc inputs. The measurement is taken on the
output power leads. The intent is to ensure that equipment
performance is not degraded from ripple voltages associated
with allowable distortion of power source voltage waveforms.
Figure 7 shows a typical audio susceptibility graph. Note that
according to the MIL-STD-461D test requirements, the in-
jected signal between 30 Hz and 5 kHz has an amplitude of
2 V rms and from 5 kHz to 50 kHz the amplitude decreases
inversely with frequency to 0.2 V rms. The curve of the in-
jected signal should be multiplied by the audio susceptibility
curve to determine the output ripple at any frequency. When
this is done, the worst case output ripple at the frequency of
the input ripple occurs at 5 kHz, at which point there is typi-
cally a 25 mV peak-to-peak output ripple.
It should be noted that MIL-STD-704 has a more relaxed
requirement for rejection of low frequency differential signals
injected on the dc inputs than MIL-STD-461D. MIL-STD-
704 calls for a lower amplitude ripple to be injected on the
input in a narrower frequency band, 10 Hz to 20 kHz.
IN
line. While the measurement taken from the
–16–
CS114: This test measures the ability of the converter to oper-
ate correctly during and after being subjected to currents in-
jected into bulk cables in the 10 kHz to 400 MHz range. Its
purpose is to simulate currents that would be developed in these
cables due to electromagnetic fields generated by antenna trans-
missions. The converter is designed to meet the requirements
of this test when the current is injected on the input power leads
cable. Consult factory for more information.
CS115: This test measures the ability of the converter to oper-
ate correctly during and after being subjected to 30 ns long
pulses of current injected into bulk cables. Its purpose is to
simulate transients caused by lightning or electromagnetic
pulses. The converter is designed to meet this requirement
when applied to its input power leads cable. Consult factory for
more information.
CS116: This test measures the ability of the converter to oper-
ate correctly during and after being subjected to damped sinu-
soid transients in the 10 kHz to 100 MHz range. Its purpose is
to simulate current and voltage waveforms that would occur
when natural resonances in the system are excited. The con-
verter is designed to meet this requirement when applied to its
input power leads cable. Consult factory for more information.
RE101: This requirement limits the strength of the magnetic
field created by the converter in order to avoid interference with
sensitive equipment located nearby. The measurement is made
from 30 Hz to 100 kHz. The most stringent requirement is for
the Navy. Figure 13 shows the test results when the pickup coil
is held 7 cm above the converter. As can be seen, the converter
easily meets this requirement.
RE102: This requirements limits the strength of the electric
field emissions from the power converter to protect sensitive
receivers from interference. The measurement is made from
10 kHz to 18 GHz with the antenna oriented in the vertical
plane. For the 30 MHz and above range the standard calls for
the measurement to be made with the antenna oriented in the
horizontal plane, as well.
In a typical power converter system setup, the radiated emis-
sions can come from two sources: 1) the input power leads as
they extend over the two meter distance between the LISNs and
the converter, as required for this test, and 2) the converter
output leads and load. The latter is likely to create significant
emissions if left uncovered since minimal EMI filtering is
provided at the converter’s output. It is typical, however,
that the power supply and its load would be contained in a
conductive enclosure in applications where this test is applicable.
A metal screen enclosure was therefore used to cover the con-
verter and its load for this test.
Figure 14 shows test results for the vertical measurement and
compares them against the most stringent RE102 requirement;
the horizontal measurement (30 MHz and above) was similar.
As can be seen, the emissions just meet the standard in the
18 MHz–28 MHz range. This component of the emissions is
due to common-mode currents flowing through the input power
leads. As mentioned in the section on CE102 above, the level
of common-mode current that flows is dependent on how the
load is connected. This measurement is therefore a good indi-
cation of how well the converter will perform in the final con-
figuration, but the user should confirm RE102 testing in the
final system.
REV. A