NOT RECOMMENDED FOR NEW DESIGNS
Features
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DC/DC C
OnVerters
28 V
Olt
i
nput
MTW SERIES
30 WATT
–55°C to +85°C operation
18 to 40 VDC input
(19 to 40 VDC MTW2805S)
Fully isolated
MODELS
VDC O
utput
single
50 V for 50 ms transient protection
Fixed frequency
Inhibit function
5
12
15
Dual
±12
±15
Remote sense on MTW2805S model
Indefinite short circuit protection
Up to 86% efficiency
Size (max.): 2.720 x 1.350 x 0.505 inches (69.09 x 34.29 x 12.83 mm)
See case J5 for dimensions.
Weight:
60 grams max.
Screening: Standard or ES. See screening table for more information.
description
The MTW Series™ of DC/DC converters offer the high efficiency
and wide input voltage range of switching regulators with the isola-
tion, excellent output regulation, and low output noise typical of linear
regulators without requiring the use of external components. MTW
converters are built using thick-film hybrid technology and are sealed
in metal packages for military, aerospace and other high-reliability
applications. Unscreened models are sealed with solder and are
guaranteed to pass a gross leak test (maximum leak rate of 1 x 10
-3
atm.-cc/sec). Environmentally screened models (/ES) are hermetically
sealed with solder and will pass a fine leak and gross leak test as
described in Section C2.
MTW converters use a constant frequency pulse-width modulated
switching regulator design operating in the forward mode with a
clock switching frequency of 240 to 300 kHz. Isolation is achieved
through the use of a transformer in the forward power circuit and an
optocoupler in the feedback control loop. The full load output power
of 30 watts is available over the entire 18 to 40 VDC (19 to 40 VDC
for MTW2805S) input range. On dual output models, up to 90% of
full power is available from either output up to a combined total of 30
watts. Input transients of 50 V to up to 50 ms. duration will not impair
normal operation.
Efficiency is high over the entire input voltage range and from approxi-
mately 25% of full load to full load (see typical efficiency curves).
MTW converters are provided with indefinite short circuit protection
through the use of current limiting techniques. When the output current
reaches approximately 125% of the full rated load, the output voltage
begins to reduce to protect the converter. The converter can sustain a
true short circuit condition indefinitely.
With temperatures measured at the baseplate, the MTW Series is
rated for full power operation from –55°C to +85°C with the power
derated linearly to 0 at 115°C. The MTW’s flanged case facilitates
Crane Aerospace & Electronics
Electronics Group (Interpoint Brand)
PO Box 97005 • Redmond WA 98073-9705
425.882.3100 • power@crane-eg.com
www.interpoint.com
removal of heat and provides for mechanically secure mounting.
In applications requiring full power operation, an efficient heat sink
attached to the baseplate is required.
An inhibit is provided to allow power shut-down and start-up from a
logic input. An open circuit on the inhibit pin allows normal operation,
while a connection between the inhibit pin and input common disables
the internal oscillator and shuts down the output. In the inhibit mode,
approximately 1 mA must be sunk from pin the inhibit pin. An open
collector, active low, is required to activate the inhibit function.
All MTW converters are characterized by close output regulation over
the entire operating range with no minimum power requirement. On 12
and 15 VDC output models, typical line regulation is 10 to 20 mv. The
MTW2805S model uses external remote sense pins which monitor the
voltage at the load to provide typical regulation in the 5 to 7 mV range.
The voltage sensing circuitry operates in a true four terminal voltage
mode, eliminating the adverse effects of line resistance voltage drops.
The remote sense pins may be left unconnected, but see cautions
in on the following pages. For normal operation, remote sense pins
should be connected to their respective output pins.
The MTW Series offers low noise on both the input and output line. in
the single output converters, two-section L-C filters at both the input
and output limit output ripple voltage and minimize reflected ripple
on the input line. A small value (1000 pF, 500 V) ceramic capacitor
connected between the case and input common pin of the single
volt output models will reduce EMI on the input lines to levels near
those required by MIL-STD-461C’s CE03 standard. In the dual output
converters, single-section L-C filters are used at the input and outputs.
If compliance with MIL-STD-461 is necessary, use of Interpoint’s FMA-
416 EMI filter or FM-704A transient suppressor is recommended.
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MTW Rev C 20100212
INTERPOINT [ INTERPOINT CORPORATION COMPANY ]
