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These extremely compact DC-DC converters incorporate all
necessary input and output filtering, signalling, and protection
features, which are required in the majority of applications.
The converters provide important advantages such as flexible
output power through primary current limitation, extremely
high efficiency, excellent reliability, very low ripple and RFI
noise levels, full input-to-output isolation, negligible inrush
current, soft start, overtemperature protection, and input
over-/undervoltage lockout.
The converters are particularly suitable for rugged
environment, such as railway applications. They have been
designed in accordance with the European railway
standards EN 50155 and EN 50121-3-2. All printed circuit
boards are coated with a protective lacquer. The converter
inputs are protected against surges and transients
occurring on the source lines and cover a total input voltage
range from 16 to 150 VDC with five different types. The
outputs are continuously open- and short-circuit proof.
Full system flexibility and n+1 redundant operating mode are
possible due to series or parallel connection capabilities of
the outputs under the specified conditions. When several
converters (with 3.3 and 5 V outputs) are connected in
parallel, the T option can be employed using a single wire
connection between the converters to ensure good current
sharing. LEDs at the front panel and an isolated output OK
option indicate the status of the converter. Voltage
suppressor diodes and an independent second control loop
protect the outputs against an internally generated
overvoltage.
The converters are designed using planar magnetics
transformers and control circuits in hybrid technology. There
are always two powertrains fitted to a converter, each
consisting either of a single output with synchronous rectifier
or of a controlled main output with a tracking second output.
The output power may be flexibly distributed among the main
and the tracking output of each powertrain. Close magnetic
coupling in the transformers and output conductors together
with circuit symmetry ensure tight tracking of the auxiliary
output. The switching frequency is fixed.
As a modular power supply or as part of a distributed power
supply system, the low-profile design significantly reduces
the required volume without sacrificing high reliability. The
converters are particularly suitable for 19" rack systems
occupying 3U/4TE only, but they can also be chassismounted
by means of four screws. Connector type is H15 (or
H15S2 for some single-output models). The fully enclosed
black-coated aluminium case acts as heat sink and RFI
shield and protects the converter together with the coating of
all components against environmental impacts.
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