Application Notes

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Adjusting the Output Voltage of the PT4840

Dual Output Voltage DC/DC Converters

ries of DC/DC converters can be independantly adjusted

by up to ±10% from their factory pre-set voltage. The

The value of the resistor determines the magnitude of

adustment, and the placement of the resistor determines

the direction of adjustment (up or down). The resistor

value can be calculated directly from a simple formula.

The constants are given in Table 1. Alternatively, Table 2

provides the resistor values for a select number of output

voltages. The placement of each resistor is as follows.

Refer to Figure 1 for further information on resistor

placement.

Figure 1

Notes:

possible.

pins will affect the stability of the respective regulated

output.

The adjust resistor values may be calculated. Use the

applicable formula and select the appropriate constants

from Table 1 for the output and model being adjusted.

=

k

Ω

=

k

Ω

PT4840 Series

+V

IN

– V

IN

+Vo

1

+Vo

2

+Vo

3

PT4840

1

2

11

15, 16

22, 23

3

Vo

1

COM

COM

Vo

2

Vo

3

+V

IN

-V

IN

EN 1

Vo

Vo

17

21

C

OUT 1

C

OUT 3

C

OUT 2

C

IN

4

EN 2

( R

Ad j Down

R

3

Ad j ust Up

( R

Ad j Down

R

1

Ad j ust Up

12, 13

18 – 20

COM