Product Specifications

NV Series: 4 - 6W DC/DC Converters

Oct 2001

9-36V, 18-36V, 36-72V & 16-75V Inputs

3.3V, 5.0V, 12V, 15V, ±5.0V, ±12V, ±15V & ±24V Outputs

18-Oct-01

Rev 1.0

Page 6 of 11

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Output Current Limiting

When

the

output

is

overloaded

above

the

maximum output current rating, the voltage will

start to reduce to maintain the output power to a

safe level.

In a condition of high overload or

short-circuit where the output voltage is pulled

below approximately 30% of Vo.Nom, the unit will

enter a ‘Hiccup’ mode of operation.

Under this

condition

the

unit

will

attempt

to

restart,

approximately every 100ms until the overload has

cleared.

Parallel Operation

Paralleling of two converters is possible by direct

connection of the output voltage terminal pins.

The load regulation characteristic is designed to

facilitate current sharing (typically ± 20%).

Series Operation

The outputs of two units may be connected in series to

achieve a higher system voltage.

Safety Considerations

These converters feature 1500 Volt DC isolation

from

input

to

output.

The

input

to

output

resistance is greater than 10MOhm.

These

converters

are

provided

with

Operational

Insulation

between

input

and

output

circuits

according to EN60950 / UL1950 / CSA60950-00.

Nevertheless, if the system using the converter

needs to receive safety agency approval, certain

rules must be followed in the design of the

system.

In particular, all of the creepage and

clearance requirements of the end-use safety

requirements

must

be

observed.

These

documents include UL60950, CSA60950-00 and

EN60950,

although

specific

applications

may

have additional requirements.

In order for the output of the converter to be

considered as SELV (Safety Extra Low Voltage)

or TNV-1, according to EN60950

/ UL1950 /

CSA60950-00, one of the following requirements

must be met in the system design:

• The converter has no internal fuse.

An

external fuse must be provided to protect the

system

from

catastrophic

failure.

The

recommended fuse values are shown below:

Input Voltage Range

Recommended Fuse

36-75V

F0.315A

18-36V

F0.5A

9-36V

F1.0A

18-75V

F0.5A

• The user can select a lower rating fuse based

upon the inrush transient and the maximum

input current of the converter, which occurs at

the minimum input voltage.

Both input traces

and the chassis ground trace (if applicable)

must be capable of conducting a current of 1.5

times the value of the fuse without opening.

The fuse must not be placed in the grounded

input line, if any.

• If the voltage source feeding the module is

SELV,

the

output

of

the

converter

is

considered SELV and may be grounded or

ungrounded.

• The circuitry of the converter may generate

transients, which exceed the input voltage.

Even if the input voltage is SELV (<60V) the

components

on

the

primary

side

of

the

converter

may

have

to

be

considered

as

hazardous. A safety interlock may be needed

to

prevent

the

user

from

accessing

the

converter while operational.