1

+

POSITIVE

INPUT

INHIBIT

FB

SHUTDOWN

PWM

CONTROLLER

INPUT

COMMON

+

+

DUAL MODELS ONLY

NEGATIVE

OUTPUT

OUTPUT

COMMON

POSITIVE

OUTPUT

3

4

6

1

7

2

0.47

µF

typical

MCH SERIES

1.5 WATT

• -55°C to +125°C operation

• 12 to 50 VDC input

• Fully isolated

• Magnetic feedback

• Fixed frequency 370 kHz typ.

• Topology – Current Mode Flyback

• 80 V for up to 120 ms transient protection

(70 V for 15 V single and dual models)

• Inhibit function

• Short circuit protection

• Undervoltage lockout

MODELS

DESCRIPTION

With a miniature footprint of just 0.8 square inches, the MCH

Series™ of DC/DC converters delivers 1.5 watts of output power

while saving significant board real estate. The wide input voltage

range of 12 to 50 VDC accepts the varying voltages of military, aero-

space, or space bus power and tightly regulates output voltages to

protect downstream components. Transient protection of 80 volts for

up to 120 milliseconds exceeds the requirements of MIL-STD-704A

for the 5, 5.2, and 12 volt single models and the 12 volt dual model.

The 15 volt single and dual converters will withstand transients of up

to 70 volts for up to 120 milliseconds.

MCH Series DC/DC converters incorporate a continuous flyback

topology with a constant switching frequency of approximately 370

kHz. Current-mode pulse width modulation (PWM) provides output

voltage regulation. Output error voltage is magnetically fed back to

the input side of the PWM to regulate output voltage. Regulation is

also affected by the load; refer to the Electrical Characteristics

tables on the following pages.

Dual models regulate the negative output with magnetic coupling to

the positive output. Up to 80% of the total load may be on one output

providing that the other output carries a minimum of 20% of the total

load. The dual models can be used at double the output voltage by

connecting the load between positive and negative outputs, leaving

the common unconnected. (ex: MCH2805D can be used as a 10

VDC output.)

When an open collector TTL logic low is applied to the inhibit

terminal, pin 7, the converter shuts down and lowers the output

voltage to near zero and input current to as low as 2.3 mA. Leaving

the terminal open or applying an open collector TTL logic high will

enable the converter.

Undervoltage lockout prevents the MCH Series converters from

operating below approximately 8 VDC input voltage to keep system

current levels smooth, especially during initialization or re-start oper-

ations. All models include a soft-start function to prevent large

current draw and minimize overshoot. The converters also provide

short circuit protection by restricting the current.

MIL-STD-461

Use Interpoint’s FMSA-461 EMI filter to pass the CE03 requirements

of MIL-STD-461C.

The MCH Series converters are packaged in hermetically sealed,

projection-welded metal cases which provide EMI/RFI shielding.

SINGLES

5

5.2

12

15

DUALS

±5

±12

±15

Size (max.): 0.980 x 0.805 x 0.270 inches (24.89 x 20.45 x 6.86 mm)

Weight:

12 grams max.

Screening:

Standard, ES, or 883 (Class H)