rev.

page

date

DESCRIPTION: dc-dc converter

4 of 6

05/2009

20050

phone

phone 503.612.2300 fax

fax 503.612.2382

PART NUMBER: VHB75

2. OUTPUT TRIMMING (OPTIONAL)

The output voltages are preset to nominal values as indicated by the models table at the factory. If desired, the output voltage may

optionally be trimmed to a different value (+/- 10%) with external resistors and/or potentiometer as shown below.

To trim the output voltage with fixed resistors, the output voltage can be calculated as follows.

Trim-Up

Trim-Down

FIGURE 3: TRIM-UP VOLTAGE SETUP

FIGURE 4: TRIM-DOWN VOLTAGE SETUP

Table 1. For example, to trim-up the output voltage of 5.0V

Table 2. For example, to trim-up the output voltage of 5.0V

as follows:

as follows:

R load

10KΩ

Trimpot

+Vin

-Vin

-Vo

-S

Trim

+S

+Vo

FIGURE 2. TRIMMING WITH

EXTERNAL POTENTIOMETER

16.923

14.76

13.304

8.25

7.2

8.25

Ω

Ω

42.215

25.474

19.656

5.8

3.168

2.877

24V

15V

12V

5V

3.3V

2.5V

Table 1

R load

R trim-up

+Vin

-Vin

+Vo

+S

Trim

-S

-Vo

R load

R trim-down

+Vin

-Vin

+Vo

+S

Trim

-S

-Vo

R2 = 8.25 KΩ

R1 = 5.8 KΩ

o

o, nom = 5.4 - 5.0 = 0.4 V

V - V

=

= 6.25 (K

Ω)

R

0.4

trim-up

5.8 - 8.25 x 0.4

V

- V

=

= 3.93 (K

Ω)

R

0.4

trim-down

5.8 - 10.57 x 0.4

R2 = 10.57 KΩ

R1 = 5.8 KΩ

o

o, nom

= 5.0 - 4.6 = 0.4 V

=

(K

Ω)

R

o

o, nom

V - V

o

o, nom

trim-up

R1 - R2 x (V - V

)

=

(K

Ω)

R

o

o, nom

V

- V

o

o, nom

trim-down

R1 - R2 x (V

- V )

130

94

60.1

10.57

15

10.57

Ω

Ω

430

150

86.45

5.8

6.18

2.923

24V

15V

12V

5V

3.3V

2.5V

Table 2

For more information, please visit the product page.