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MTW Rev C 20100212

Crane Aerospace & Electronics

Electronics Group (Interpoint Brand)

PO Box 97005 • Redmond WA 98073-9705

425.882.3100 • power@crane-eg.com

www.interpoint.com

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.

Features

• –55°C to +85°C operation

• 18 to 40 VDC input

(19 to 40 VDC MTW2805S)

• 50 V for 50 ms transient protection

• Fully isolated

• Fixed frequency

• Remote sense on MTW2805S model

• Inhibit function

• Indefinite short circuit protection

• Up to 86% efficiency

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

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

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.

MODELS

single

5

12

15

Dual

±12

±15

MTW SERIES

30 WATT

NOT RECOMMENDED FOR NEW DESIGNS