ATW28XXD_06 Datasheet, PDF (6/8 Pages) International Rectifier – HYBRID-HIGH RELIABILITY DC/DC CONVERTERS

ATW28XXD Series
+Input
1
Enable
8
Sync
2
EMI
Filter
Drive 1
Drive 2
Pulse Width
Modulator ^FB
Block Diagram
Error Amp
& Reference
3 +Vout
4
Output
Return
5 -Vout
Input
Return
10
Application Information
Inhibit Function (Enable)
Connecting the inhibit input (Pin 8) to input common (Pin 10)
will cause the converter to shut down. It is recommended
that the inhibit pin be driven by an open collector device
capable of sinking at least 400µA of current. The open
circuit voltage of the inhibit input is 11.5 ±1.0VDC.
EMI Filter
An optional external EMI filter (AFC461) is available that will
reduce the input ripple current to levels below the limits
imposed by MIL-STD-461B CEO3.
Device Synchronization
Whenever multiple DC/DC converters are utilized in a single
system, significant low frequency noise may be generated
due to the slight differences in the switching frequencies of
the converters (beat frequency noise). Because of the low
frequency nature of this noise (typically less than 10KHz), it
is difficult to filter out and may interfere with proper operation
of sensitive systems (communications, radar or telemetry).
International Rectifie roffers an option,which allows
synchronization of multiple AHE/ATW type converters, thus
eliminating this type of noise.
To take advantage of this capability, the system designer
must assign one of the converters as the master. Then, by
definition, the remaining converters become slaves and will
operate at the masters’ switching frequency.
The user should be aware that the synchronization
system is fail-safe; that is, the slaves will continue
operating should the master frequency be interrupted for
any reason. The layout must be such that the synchronization
output (pin 2) of the master device is connected to the
synchronization input (pin 2) of each slave device. It is
advisable to keep this run short to minimize the possibility
of radiating the 250KHz switching frequency.
The appropriate parts must be ordered to utilize this
feature. After selecting the converters required for the
system, a ‘MSTR’ suffix is added for the master converter
part number and a ‘SLV’ suffix is added for slave part
number. See Part Number section.
Typical Synchronization Connection
+ In
Return
AFC461
or
AFV461
Output
Return
System
Bus
+ In
Output
Case ATW28xxS
Return
MSTR
Return
+ In _ATW28xxD Output
Case or Other Return
Return Compatable Output
SLV
+ In
Output
Case ATW28xxD Return
Return
Output
SLV
6
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