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參數(shù)資料
| 型號： | ADDC02805SA |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 28 V/66 W/100 W DC/DC Converters with Integral EMI Filter |
| 中文描述： | 28 V/66 W/100中西區(qū)區(qū)議會/ DC轉(zhuǎn)換器與積分EMI濾波器 |
| 文件頁數(shù)： | 13/18頁 |
| 文件大?。?/td> | 241K |
| 代理商： | ADDC02805SA |
ADDC02803SC/ADDC02805SA
REV. A
–13–
supply. A lower voltage rating capacitor (500 V) was therefore
chosen to fit more capacitance in the same space in order to
better meet the conducted emissions requirement of MIL-STD-
461D (CE102). For those applications requiring 250 V or less
of isolation from input to output, the present designs would
meet NAVMAT guidelines.
Switching Transistors:
100 V MOSFETs are used in the
standard unit to switch the primary side of the transformers.
Their nominal off-state voltage meets the NAVMAT derating
guidelines. When the MOSFETs are turned off, however, mo-
mentary spikes occur that reach 100 V. The present generation
of MOSFETs are rated for repetitive avalanche, a condition that
was not considered by the NAVMAT deratings. In the worst
case condition, the energy dissipated during avalanche is 1% of
the device’s rated repetitive avalanche energy. To meet the
NAVMAT derating, 200 V MOSFETs could be used. The
100 V MOSFETs are used instead for their lower on-state resis-
tance, resulting in higher efficiency for the power supply.
NAVMAT Junction Temperatures:
The two types of power
deratings (current and temperature) can be independent of one
another. For instance, a switching diode can meet its derating
of 70% of its maximum current, but its junction temperature
can be higher than 110
°
C if the case temperature of the con-
verter, which is not controlled by the manufacturer, is allowed
to go higher. Since some users may choose to operate the power
supply at a case temperature higher than 90
°
C, it then becomes
important to know the temperature rise of the hottest semicon-
ductors. This is covered in the specification table in the section
entitled Thermal Characteristics.
EMI CONSIDERATIONS
The ADDC02803SC and ADDC02805SA have an integral
differential- and common-mode EMI filter designed to meet all
applicable requirements in MIL-STD-461D when the power
converters are installed in a typical system setup (described
below). The converters also contain transient protection circuitry
that permit the units to survive short, high voltage transients across
their input power leads. The purpose of this section is to
describe the various MIL-STD-461D tests and the converters’
corresponding performance. Consult factory for additional
information.
The figures and tests referenced herein were obtained from
measurements on the ADDC02805SA, a single 5 V dc output
converter. Since the construction and topology of the 3.3 V
output converter is almost identical to the 5 V dc output con-
verter, and the component values of the EMI differential- and
common-mode filter in the 3.3 V output converter are identical
to the 5 V output converter, the text references these figures and
tests as typical of the ADDC02803SC converter as well.
Electromagnetic interference (EMI) is governed by MIL-STD-461D,
which establishes design requirements, and MIL-STD-462D,
which defines test methods. EMI requirements are categorized
as follows (xxx designates a three digit number):
CExxx: conducted emissions (EMI produced internal to the
power supply which is conducted externally through its input
power leads)
CSxxx: conducted susceptibility (EMI produced external to the
power supply which is conducted internally through the input
power leads and may interfere with the supply’s operation)
RExxx: radiated emissions (EMI produced internal to the
power supply which is radiated into the surrounding space)
RSxxx: radiated susceptibility (EMI produced external to the
power supply which radiates into or through the power supply
and may interfere with its proper operation)
It should be noted that there are several areas of ambiguity with
respect to CE102 measurements that may concern the systems
engineer. One area of ambiguity in this measurement is the
nature of the load. If it is constant, the ripple voltage on the
converter’s input leads is due only to the operation of the con-
verter. If, on the other hand, the load is changing over time,
this variation causes an additional input current and voltage
ripple to be drawn at the same frequency. If the frequency is
high enough, the converter’s filter will help attenuate this second
source of ripple, but if it is below approximately 100 kHz, it will
not. The system may then not meet the CE102 requirement,
even though the converter is not the source of the EMI. If this
is the case, additional capacitance may be needed across the
load or across the input to the converter.
Another ambiguity in the CE102 measurement concerns common-
mode voltage. If the load is left unconnected from the ground
plane (even though the case is grounded), the common-mode
ripple voltages will be smaller than if the load is grounded. The
test specifications do not state which procedure should be used.
However, in neither case (load grounded or floating) will the
typical EMI test setup described below be exactly representative
of the final system configuration EMI test. For the following
reasons, the same is true if separately packaged EMI filters are
used.
In almost all systems the output ground of the converter is ulti-
mately connected to the input ground of the system. The para-
sitic capacitances and inductances in this connection will affect
the common-mode voltage and the CE102 measurement. In
addition, the inductive impedance of this ground connection
can cause resonances, thereby affecting the performance of the
common-mode filter in the power supply.
In response to these ambiguities, the Analog Devices’ converter
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 cor-
rupt the power quality (allowable voltage distortion) on the
power buses 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 19 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.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADDC02805SAKV | 制造商:AD 制造商全稱:Analog Devices 功能描述:28 V/66 W/100 W DC/DC Converters with Integral EMI Filter |
| ADDC02805SATV | 制造商:AD 制造商全稱:Analog Devices 功能描述:28 V/66 W/100 W DC/DC Converters with Integral EMI Filter |
| ADDC02805SATV/QMLH | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DC-to-DC Voltage Converter |
| ADDC02808PB | 制造商:AD 制造商全稱:Analog Devices 功能描述:28 V, 200 W Pulsed DC/DC Converter with Integral EMI Filter |
| ADDC02808PBKV | 制造商:AD 制造商全稱:Analog Devices 功能描述:28 V, 200 W Pulsed DC/DC Converter with Integral EMI Filter |
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