MHF2815D datasheet(2/23 Pages) INTERPOINT

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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.

Converter Design

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.

inhibit FunCtion

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.

soFt start Feature

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.

synChronization

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.

short CirCuit ProteCtion

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.

unDervoltage loCkout

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

PaCkaging

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.

outPut voltage oPtions

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 Patents

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

Page 2 of 23

Crane aerospace & electronics Power solutions

MHF+ Single, dual and triple dC/dC Converters

28 VOlT inPuT – 15 WATT

MHF+ rev l - 20091113

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