Size (max.): 3.20 x 2.46 x 0.595 inches (81.3 x 62.5 x 15.11 mm)

See case L for dimensions.

Weight:

140 grams typical

Screening: Standard or ES. See screening table for more information.

modELS

Dual

±12

±15

tRIplE

+5 & ±12

+5 & ±15

description

The mFW Series™ of dC/dC converters offers up to 70 watts of power

from dual or triple outputs in one package. Using hybrid thick film tech-

nology a power density of over 20 watts per cubic inch is achieved.

These devices are packaged in hermetically sealed cold rolled steel

enclosures with a tin plate finish making them ideal for use in military,

aerospace, or other high reliability applications. Unscreened models

are guaranteed to pass a gross leak test (maximum leak rate of 0.001

atm-cc/sec). Environmentally screened units (designated by the /ES

suffix) are hermetically solder sealed. See Section C2 for screening

specifications.

The mFW Series converters utilize a quasi-square wave forward

converter design with a nominal switching frequency of 245 kHz.

Isolation between input and output is provided with a transformer in the

forward power loop and a wideband, temperature insensitive optical

link in the feedback control loop. output regulation is accomplished

with constant frequency pulse width modulation. In addition, the load

regulation of the single output models is further enhanced through

the use of remote output voltage sense pins to overcome the adverse

effects of line resistance voltage drops. Short circuit protection is

provided by detecting peak primary switching current on a cycle by

cycle basis and limiting it to approximately 130% of the full load input

current. This method results in quick and positive current limiting under

short circuit conditions.

The mFW Series converters offer low noise on both the input and

output lines. A two section, four pole LC input filter is included to

provide very low reflected line ripple current. Adherence to mIL-STd-

461C (CE03) is possible with the addition of the FmB-461 filter. output

ripple is maintained at less than 50 mV p-p for single and dual output

models and 85 mV for triple output models.

All models of the mFW Series are designed to provide full power

operation over an input voltage range of 19 to 40 VdC. operation

below an input of 19 volts, including operation in mIL-STd-704E emer-

gency power conditions, is possible with derated output power. Please

refer to the derating information and the low voltage drop-out graphs

(Figures 10 and 11) on the following pages.

Full load operation of any of the mFW Series converters is available

at case temperatures of –55°C to + 85°C. operation up to +125°C is

possible with derated output power. The mFW Series converters are

provided in a flange mount case designed to facilitate the removal of

internally generated heat. Because of this, heat sinking requirements

are minimal. Sustained full power operation does however require that

an efficient heat sink be attached to the baseplate. Please refer to the

heat sink requirements section for more information.

Standard on all models of the mFW Series is a dual mode inhibit/sync

pin. This pin serves as both an output inhibit and as a synchronization

input. In the inhibit mode an open collector TTL compatible low (<0.8

V) will disable internal switching thereby inhibiting the unit’s output.

Inhibiting in this manner results in an extremely low quiescent current.

Since a pull-up resistor is included internally, this pin may be left open

should the inhibit function not be desired.

In a digital system it is often desirable to synchronize the input or

output ripple with the system clock. For this reason each model of the

mFW Series was designed to synchronize with a system clock applied

to the inhibit/sync pin. Please refer to the technical data section for

timing details for the external sync feature.

Features

• –55°Cto+85°Coperation

• 19to40VDCinput

• 50Vfor50mstransientprotection

• Fullyisolated

• Fixedfrequencyswitching

• Remotesenseonsinglemodels

• Inhibit/syncfunction

• Indefiniteshortcircuitprotection

• Upto84%efficiency

mFwSeRIeS

70 WATT

NOT RECOMMENDED FOR NEW DESIGNS

Page 1 of 7

mFwRevF20100212

Crane Aerospace & Electronics

Electronics Group (Interpoint Brand)

POBox97005•RedmondwA98073-9705

425.882.3100•power@crane-eg.com

www.interpoint.com