ADDC02812DAKV 查看數據表（PDF） - Analog Devices

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ADDC02812DAKV

28 V/100 W DC/DC Converters with Integral EMI Filter

Analog Devices 

ADDC02812DA/ADDC02815DA

typical audio susceptibility graph. Note that according to the enclosure in applications where this test is applicable. A metal

MIL-STD-461D test requirements, the injected signal between screen enclosure was therefore used to cover the converter and

30 Hz and 5 kHz has an amplitude of 2 V rms and from 5 kHz

its load for this test.

to 50 kHz the amplitude decreases inversely with frequency to

0.2 V rms. The curve of the injected 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 typically a 25 mV peak-to-peak output

ripple.

Figure 16 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

It should be noted that MIL-STD-704 has a more relaxed

common-mode current that flows is dependent on how the load

requirement for rejection of low frequency differential signals

is connected. This measurement is therefore a good indication

injected on the dc inputs than MIL-STD-461D. MIL-STD-

of how well the converter will perform in the final configuration,

OBSOLETE 704 calls for a lower amplitude ripple to be injected on the input

in a narrower frequency band, 10 Hz to 20 kHz.

CS114: This test measures the ability of the converter to operate

correctly during and after being subjected to currents injected

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 transmissions.

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.

but the user should confirm RE102 testing in the final system.

RS101: This requirement is specialized and is intended to

check for sensitivity to low frequency magnetic fields in the

30 Hz to 50 kHz range. The converter is designed to meet this

requirement. Consult factory for more information.

RS103: This test calls for correct operation during and after the

unit under test is subjected to radiated electric fields in the

10 kHz to 40 GHz range. The intent is to simulate electro-

magnetic fields generated by antenna transmissions. The con-

verter is designed to meet this requirement. Consult factory for

more information.

Circuit Setup for EMI Test

Figure 17 shows a schematic of the test setup used for the EMI

measurements discussed above. The output of the converter is

connected to a resistive load designed to draw full power. There

is a 0.1 µF capacitor placed across this resistor that typifies

by-pass capacitance normally used in this application. At the

CS116: This test measures the ability of the converter to oper-

ate correctly during and after being subjected to damped sinu-

input of the converter there are two differential capacitors (the

larger one having a series resistance) and two small common-

soid transients in the 10 kHz to 100 MHz range. Its purpose is

to simulate current and voltage waveforms that would occur

mode capacitors connected to case ground. The case itself was

connected to the metal ground plane in the test chamber. For

when natural resonances in the system are excited. The con-

verter is designed to meet this requirement when applied to its

the RE102 test, a metal screen box was used to cover both the

converter and its load (but not the two meters of input power

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

lead cables). This box was also electrically connected to the

metal ground plane.

With regard to the components added to the input power lines,

the 100 µF capacitor with its 1 Ω series resistance is required to

achieve system stability when the unit is powered through the

the Navy. Figure 15 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 pro-

vided at the converter’s output. It is typical, however, that the

power supply and its load would be contained in a conductive

LISNs, as the MIL-STD-461D standard requires. These LISNs

have a series inductance of 50 µH at low frequencies, giving a

total differential inductance of 100 µH. As explained earlier in

the System Instability section, such a large series source induc-

tance will cause an instability as it interacts with the converter’s

negative incremental input resistance unless some corrective

action is taken. The 100 µF capacitor and 1 Ω resistor provide

the stabilization required.

It should be noted that the values of these stabilization compo-

nents are appropriate for a single converter load. If the system

makes use of several converters, the values of the components

will need to be changed slightly, but not such that they are

repeated for every converter. It should also be noted that most

system applications will not have a source inductance as large as

the 100 µH built into the LISNs. For those systems, a much

smaller input capacitor could be used.

The 2 µF differential-mode capacitor and the two 82 nF common-

mode capacitors were added to achieve the results shown in the

EMI measurement figures described above.

–14–

REV. 0

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