Application Notes

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Adjusting the Output Voltage of the 10W-Rated

Excalibur™ Series of Isolated DC/DC Converters

The factory pre-set output voltage of Power Trends’ 10W

Excalibur series of isolated DC-DC converters may be

adjusted over a narrow range. This is accomplished with

the addition of a single external resistor. For the input

voltage range specified in the data sheet, Table 1 gives the

Adjust Up:

An increase in the output voltage is obtained

Adjust Down:

Refer to Figure 1 and Table 2 for both the placement and value

also be calculated using the following formulas.

(R

=

56.2 (V

– R

s

k

Ω

V

Table 1

DC/DC CONVERTER ADJUSTMENT RANGE AND FORMULA PARAMETERS

Series Pt #

24V Bus

PT4247

PT4246

PT4241

PT4245

PT4242

PT4243

PT4244

48V Bus

PT4227

PT4226

PT4221

PT4225

PT4222

PT4223

PT4224

3A

3A

3A

3A

3A

2A

0.85A

1.3V

1.5V

1.8V

2.5V

3.3V

5.0V

12.0V

Vo(min)

1.2V

1.45V

1.7V

2.25V

2.95V

4.5V

10.8V

Vo(max)

1.4V

1.65V

1.98V

2.75V

3.65V

5.5V

13.2V

Ω

Ω

Ω

Ω

Ω)

340.0

243.0

243.0

187.0

187.0

110.0

49.9

Figure 1

PT4220/4240

+ V out

-V out

+V in

-V in

Remote

On/Off

V

1

3

5

8, 9

6, 7

10

L

O

A

D

+V

in

-V

in

+V

O

–V

O

(R1)

Adj Down

R2

Adjust Up

R

2

=

68.845

– R

s

k

Ω

V

Where,

V

o

= Original output voltage

V

a

= Adjusted output voltage

R

s

= Internal resistance (Table 1)

Notes:

location. Place the resistor as close to the ISR as possible.

the ISR.

3. The output power is limited to 10W. If the output

voltage is increased, the maximum load current must be

derated according to the following equation.

I

= 10

V

a

In any instance, the load current must not exceed the

converter’s rated current (See Table 1).

PT4220/4240 Series