Application Notes

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Adjusting the Output Voltage of the 30W-Rated

PT3400 Series of Isolated DC/DC Converters

The output voltage of the PT3400 Excalibur™ series of

isolated DC/DC converters may be adjusted over a limited

range from the factory-trimmed nominal value. Adjust-

ment is accomplished with a single external resistor. The

placement the resistor determines the direction of adjust-

ment, either up or down, and the value of the resistor the

magnitude of adjustment. Table 3-1 gives the allowable

Adjust Up:

An increase in the output voltage is obtained

(pin 7).

Adjust Down

(PT3401, PT3402, & PT3408 Only):

Add a

Refer to Figure 3-1 and Table 3-2 for both the placement and

also be calculated using the following formulas.

=

k

Ω

=

k

Ω

Figure 3-1

Notes:

1. The output voltage of the PT3401 (3.3V),

PT3402 (2.5V), and PT3408 (5V) may be adjusted either

higher or lower. All other models, which have an output

voltage of 1.8V or less, can only be adjusted higher.

location. Place the resistor as close to the converter as

possible.

to this pin will affect the stability of the converter.

4. If the output voltage is increased, the maximum load

current must be derated according to the following

equation.

=

In any instance, the load current must not exceed the

PT3400 Series

L

O

A

D

* Remote Sense (–)

Remote Sense (+)

+V

OUT

–V

OUT

+V

IN

–V

IN

† C

OUT

330µF

R

1

Ad j ust Up

(R

Adj Down

PT3400

1

2

11–13

8–10

14

7

3

4

–V

IN

+V

IN

EN 1

EN 2

SEQ

V

6

5

+V

OUT

–V

OUT

+V

SENSE

–V

SENSE