MODELS

B4-39

Size (max.): 2.720 x 1.350 x 0.505 inches (69.09 x 34.29 x 12.83 mm)

See Section B8, case J5, for dimensions.

Weight:

60 grams max.

Screening:

Standard only. See Section C2 for screening description.

• –40° to +85°C operation

• 18 to 36 VDC input

(19 to 36 VDC input HR301-2805)

• Fully Isolated

• Optocoupler feedback

• Fixed frequency, 240 to 300 kHz typical

• Topology – Push-Pull Forward

• 50 V for up to 50 ms transient protection

• Inhibit function

• Indefinite short circuit protection

• Remote sense on HR301-2805 model

• Up to 86% efficiency

SINGLE

5

12

15

DUAL

±12

±15

DESCRIPTION

HR300 Series™ DC/DC converters combine the small size and high

reliability of hybrid-based components, the high efficiency of

switching regulators, and the isolation, regulation, and low noise

characteristics of linear regulators.

HR300 DC/DC converters use thick-film hybrid manufacturing tech-

niques for smaller size, lighter weight and higher reliability than

converters produced with other circuit techniques. With a footprint of

less than 3.7 square inches and a 0.5 inch height, the HR300

converters reach power densities up to 22 watts per cubic inch.

The HR300 parts use the same manufacturing procedures and

quality controls that Interpoint applies to converters built for aero-

space and military applications. The converters are hermetically

sealed in metal packages that are guaranteed a maximum leak rate

HR300 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 36 VDC input range (19

to 36 HR301-2805). On dual output models, up to 90% of full power

is available from either output up to a combined total of 30 watts.

The HR300’s high efficiency is maintained over the entire input

voltage range and from approximately 25% of full load to full load

(see typical efficiency curves).

Short circuit protection is provided through foldback current limiting.

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. The HR300’s flanged case facilitates removal of heat

and provides for mechanically secure mounting. If full power opera-

tion or indefinite short circuit protection is a system requirement, the

HR300 converter should be mounted with an efficient heat sink in

contact with the mounting flange.

Internal filters in all HR300 converters provide low noise on both

the

input

and

outputs.

On

HR301

models,

two-section

L-C filters limit output ripple voltage and reflected input ripple

current. On HR302 models, single-section L-C filters perform the

same function.

For maximum output regulation, the HR301-2805 is provided with

external output voltage remote sense pins. Connecting the remote

sense pins to the load provides a four-terminal voltage mode which

eliminates the adverse effects of line resistance voltage drops.

Remote sense pins may be left unconnected, but see cautions in

this data sheet. For normal operation, remote sense pins should be

connected to the respective output pins.

An inhibit is provided to allow a logic input to shut down the

converter. An open circuit on the inhibit pin (pin 2 or 8) allows normal

operation. A connection between the inhibit pin and the input

common (pin 10) disables the internal oscillator, shutting down the

output. The inhibit pin has an open circuit voltage of 11 to 16 V on

single output models, 8 to 12 V on HR302-2812 and 10 to 14 V on

HR302-2815. In the inhibit mode, approximately 1 mA must be sunk

from the inhibit pin. An active low open collector is required to acti-

vate the inhibit function.

HR300 SERIES

30 WATT