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PDF ( 数据手册 , 数据表 ) ADDC02815DAKV

零件编号 ADDC02815DAKV
描述 28 V/100 W DC/DC Converters with Integral EMI Filter
制造商 Analog Devices
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ADDC02815DAKV 数据手册, 描述, 功能
a
FEATURES
28 V dc Input, ؎12 V dc @ 8.34 A, 100 W Output
(ADDC02812DA)
28 V dc Input, ؎15 V dc @ 6.68 A, 100 W Output
(ADDC02815DA)
Integral EMI Filter Designed to Meet MIL-STD-461D
Low Weight: 80 Grams
NAVMAT Derated
Many Protection and System Features
APPLICATIONS
Commercial and Military Airborne Electronics
Missile Electronics
Space-Based Antennae and Vehicles
Mobile/Portable Ground Equipment
28 V/100 W DC/DC Converters
with Integral EMI Filter
ADDC02812DA/ADDC02815DA
FUNCTIONAL BLOCK DIAGRAM
–SENSE
+SENSE
ADJUST
STATUS
VAUX
INHIBIT
SYNC
ISHARE
TEMP
–VIN
+VIN
OUTPUT SIDE
CONTROL
CIRCUIT
INPUT SIDE
CONTROL
CIRCUIT
EMI FILTER
ADDC02812DA/ADDC02815DA
FIXED
FREQUENCY
DUAL
INTERLEAVED
POWER TRAIN
OUTPUT
FILTER
–VOUT
–VOUT
VCOM
VCOM
+VOUT
+VOUT
GENERAL DESCRIPTION
The ADDC02812DA and ADDC02815DA hybrid military dc/
dc converters with integral EMI filter offer the highest power
density of any dc/dc power converters with their features and in
their power range available today. The converters with integral
EMI filter are a fixed frequency, 1 MHz, square wave switching
dc/dc power supply. They are not variable frequency resonant
converters. In addition to many protection features, these con-
verters have system level features that allow them to be used as a
component in larger systems as well as a stand-alone power
supply. The units are designed for high reliability and high
performance applications where saving space and/or weight are
critical.
The ADDC02812DA and ADDC02815DA are available in a
hermetically sealed, molybdenum based hybrid package and are
easily heatsink mountable. Three screening levels are available,
including military SMD.
PRODUCT HIGHLIGHTS
1. 60 W/cubic inch power density with an integral EMI filter
designed to meet all applicable requirements in MIL-STD-
461D when installed in a typical system setup
2. Light weight: 80 grams
3. Operational and survivable over a wide range of input
conditions: 16 V–50 V dc; survives low line, high line, and
positive and negative transients
4. High reliability; NAVMAT derated
5. Protection features include:
Output Overvoltage Protection
Output Short Circuit Current Protection
Thermal Monitor/Shutdown
Input Overvoltage Shutdown
Input Transient Protection
6. System level features include:
Current Sharing for Parallel Operation
Inhibit Control
Output Status Signal
Synchronization for Multiple Units
Input Referenced Auxiliary Voltage
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1997







ADDC02815DAKV pdf, 数据表
ADDC02812DA/ADDC02815DA
BASIC OPERATION
The ADDC02812DA and ADDC02815DA converters use a
flyback topology with dual interleaved power trains operating
180° out of phase. Each power train switches at a fixed fre-
quency of 500 kHz, resulting in a 1 MHz fixed switching fre-
quency as seen at the input and output of the converter. In a
flyback topology, energy is stored in the inductor during one-
half portion of the switching cycle and is then transferred to the
output filter during the next half portion. With two interleaved
power trains, energy is transferred to the output filter during
both halves of the switching cycle, resulting in smaller filters to
meet the required ripple.
A five-pole differential input EMI filter, along with a common-
mode EMI capacitor and careful attention to layout parasitics,
is designed to meet all applicable requirements in MIL-STD-
461D when installed in a typical system setup. A more detailed
discussion of CE102 and other EMI issues is included in the
section entitled EMI Considerations.
The converters use current mode control and employ a high
performance opto-isolator in their feedback path to maintain
isolation between input and output. The control circuits are
designed to give a nearly constant output current as the output
voltage drops from VO nom to VSC during a short circuit condi-
tion. It does not let the current fold back below the maximum
rated output current. The output overvoltage protection cir-
cuitry, which is independent from the normal feedback loop,
protects the load against a break in the remote sense leads.
Remote sense connections, which can be made at the load, can
adjust for voltage drops of as much as 0.25 V dc between the
converter and the load, thereby maintaining an accurate voltage
level at the load.
An input overvoltage protection feature shuts down the con-
verter when the input voltage exceeds (nominally) 52.0 V dc.
An internal temperature sensor shuts down the unit and pre-
vents it from becoming too hot if the heat removal system fails.
The temperature sensed is the case temperature and is factory
set to trip at a nominal case temperature of 110°C to 115°C.
The shutdown temperature setting can be raised externally or
disabled by the user.
Each unit has an INHIBIT pin that can be used to turn off the
converter. This feature can be used to sequence the turn-on of
multiple converters and to reduce input power draw during
extended time in a no load condition.
A SYNC pin, referenced to the input return line (Pin 10), is
available to synchronize multiple units to one switching fre-
quency. This feature is particularly useful in eliminating beat
frequencies which may cause increased output ripple on paral-
leled units. A current share pin (ISHARE) is available which
permits paralleled units to share current typically within 5% at
full load.
A low level dc auxiliary voltage supply referenced to the input
return line is provided for miscellaneous system use.
PIN CONNECTIONS
Pins 1 and 2 (؎SENSE)
Pins 1 and 2 must always be connected for proper operation,
although failure to make these connections will not be cata-
strophic to the converter under normal operating conditions. If
there is no load present on the converter, failure to make these
connections could result in damage to the device. Pin 1 must
always be connected to the output return and Pin 2 must always
be connected to +VOUT when regulating the positive voltage. If
the negative output voltage is being regulated, Pin 1 must always
be connected to –VOUT and Pin 2 must always be connected to
the output return. These connections can be made at any one
of the output pins of the converter, or remotely at the load. A
remote connection at the load can adjust for voltage drops of as
much as 0.25 V dc between the converter and the load. Long
remote sense leads can affect converter stability, although this
condition is rare. The impedance of the long power leads between
the converter and the remote sense point could affect the
converter’s unity gain crossover frequency and phase margin.
Consult factory if long remote sense leads are to be used.
Pin 3 (ADJUST)
An adjustment pin is provided so that the user can change the
nominal output voltage during the prototype stage. Since very
low temperature coefficient resistors are used to set the output
voltage and maintain tight regulation over temperature, using
standard external resistors to adjust the output voltage will
loosen output regulation over temperature. Furthermore, since
the status trip point is not changed when the output voltage is
adjusted using external resistors, the status line will no longer
trip at the standard levels of the newly adjusted output voltage.
Therefore, it is highly recommended that once the correct out-
put voltage is determined, modified standard units should be
ordered with the necessary changes made inside the package at
the factory. The ADJUST function is sensitive to noise, and
care should be taken in the routing of connections.
To make the output voltage higher, place a resistor from ADJUST
(Pin 3) to –SENSE (Pin 1). To make the output voltage lower,
place a resistor from ADJUST (Pin 3) to +SENSE (Pin 2).
Figures 18 and 19 show resistor values for a ± 5% change in
output voltage.
8
7
6
5
4
3
2
1
99 98 97 96 95
OUTPUT VOLTAGE – %
Figure 18. External Resistor Value for Reducing Output
Voltage
–8– REV. A







ADDC02815DAKV equivalent, schematic
ADDC02812DA/ADDC02815DA
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
common-mode current that flows is dependent on how the load
is connected. This measurement is therefore a good indication
of how well the converter will perform in the final configuration,
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
input of the converter there are two differential capacitors (the
larger one having a series resistance) and two small common-
mode capacitors connected to case ground. The case itself was
connected to the metal ground plane in the test chamber. For
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
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 series resistance is required to
achieve system stability when the unit is powered through the
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 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.
RELIABILITY CONSIDERATIONS
MTBF (Mean Time Between Failure) is a commonly used
reliability concept that applies to repairable items in which
failed elements are replaced upon failure. The expression for
MTBF is
MTBF = T/r
where
T = total operating time
r = number of failures
In lieu of actual field data, MTBF can be predicted per
MIL-HDBK-217.
MTBF, Failure Rate and Probability of Failure: A proper
understanding of MTBF begins with its relationship to lambda
(), which is the failure rate. If a constant failure rate is assumed,
then MTBF = 1/, or = 1/MTBF. If a power supply has an
MTBF of 1,000,000 hours, this does not mean it will last
1,000,000 hours before it fails. Instead, the MTBF describes the
failure rate. For 1,000,000 hours MTBF, the failure rate during
any hour is 1/1,000,000, or 0.0001%. Thus, a power supply
with an MTBF of 500,000 hours would have twice the failure
rate (0.0002%) of one with 1,000,000 hours.
–16–
REV. A










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