MFW2812D_10 Datasheet, PDF (1/7 Pages) Interpoint Corporation Company – –55°C to + 85°C operation 50 V for 50 ms transient protection

DC/DC Converters
28 Volt Input
NOT RECOMMENDED FOR NEW DESIGNS
mfw Series
70 Watt
Features
• –55°C to + 85°C operation
• 19 to 40 VDC input
• 50 V for 50 ms transient protection
• Fully isolated
• Fixed frequency switching
• Remote sense on single models
• Inhibit/sync function
• Indefinite short circuit protection
• Up to 84% efficiency
models
VDC Output
dual
±12
±15
TRIPLE
+5 & ±12
+5 & ±15
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.
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.
Design Methodology
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.
Low Noise
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.
Wide Voltage Range
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.
Wide Temperature Range
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.
Inhibit/Sync Feature
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.
Crane Aerospace & Electronics
Electronics Group (Interpoint Brand)
PO Box 97005•Redmond WA 98073-9705
425.882.3100 • [e-mail]
www.interpoint.com
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MFW Rev F 20100212