Crane aerospace & electronics Power solutions
MHF+ Single, dual and triple dC/dC Converters
28 VOlT inPuT – 15 WATT
MHF+ SerieS™ triPle dC/dC ConverterS
MHF+ Series™ triple dC/dC converters provide a wide input
voltage range of 16 to 48 vdC delivering 15 watts of total output
power with output voltages of +5 and ±12 or +5 and ±15 vdC.
the main output, +5 vdC, will supply up to 7.5 watts and the
auxiliaries will supply up to 7.5 watts of combined power. Full
power operation at -55° C to +125° C plus the ability to withstand
transients of up to 80 v for up to 120 milliseconds make these
converters an ideal choice for your high reliability systems.
s
oFt
s
tart
F
eature
the soft-start feature provides a controlled 25 milliseconds
maximum turn-on to minimize inrush current and reduce
overshoot at initial start-up or when inhibit is released.
s
ynChronization
C
onverter
D
esign
MHF+ triple Series of dC/dC converters incorporate dual-phase,
phase-shifted technology with a continuous flyback topology.
this design eliminates a minimum load requirement on the main
output and eliminates cross regulation effects between the main
output voltage and auxiliary output voltages. See Figure 2.
the phase-shifted design offers reduced input and output ripple.
to meet Mil-Std-461 requirements use an eMi filter, see Figure
5. FMH-461 is the recommended filter.
to synchronize the converter’s switching frequency to a system
clock apply the clock signal to the sync terminal (pin 7). When
multiple converters are powered from a single power source,
asynchronous (free run) operation will result in lower peak
noise for common spectral peaks, but synchronous operation
will eliminate any possibility of interference frequencies in the
low audio band. Source impedance of the signal should be
less than 100 ohms and the transition time should be less than
100 nanoseconds. the capacitively coupled sync input will
synchronize on a differential signal of as low as 4 volts to as high
as 5 v. For triple output models, if the sync function is not used,
the terminal should be left open. See Figure 4.
i
nhibit
F
unCtion
an open collector inhibit terminal (pin 1) provides shut-down and
start-up control. applying an active low of <0.8 v, referenced to
input common, will disable the output of the converter. When
inhibited, input current is reduced to 5 ma or less and there is no
generation of switching noise. the inhibit terminal typically sinks
3 ma when the converter is inhibited.
leaving the terminal open or pulling it high will enable the
converter. use an open collector interface for active high voltages
of up to 11 volts. (refer to Figure 2 for a connection diagram.)
an open collector interface is not required if the active high is in
excess of the open circuit voltage of the inhibit terminal (11 volts)
but less than 40 volts. See Figure 2.
s
hort
C
irCuit
P
roteCtion
on the triple output models, internal current limiting circuitry
protects on all three outputs against short circuits. When output
power exceeds approximately 130% of maximum output power,
the output currents are limited. in addition, separate current
limiting circuitry protects each output individually resulting in
normal operation of either the main or the auxiliaries, whichever
is not in a shorted condition.
u
nDervoltage
l
oCkout
undervoltage lockout prevents the triple output models units from
operating below approximately 8.5 vdC input voltage to keep
system current levels smooth, especially during initialization or
re-start operations.
MHF+ SerieS™ all ModelS
P
aCkaging
MHF+ Series of converters are packaged in hermetically sealed
metal cases and can be purchased in a flanged or non-flanged
case. the flanged option provides increased heat dissipation and
also provides greater stability when mechanically secured.
o
utPut
v
oltage
o
Ptions
the MHF+ Series converters are capable of providing other
output voltage options in addition to those characterized on this
datasheet. Contact your sales representative to discuss other
output voltage options.
us P
atents
interpoint converters may use one or more of the following uS
patents 5,521,807, 5,694,303 and 5,631,822.
www.interpoint.com
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MHF+ rev l - 20091113
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
