page

date

DESCRIPTION: chassis mount dc-dc converter

6 of 10

04/2011

20050

phone

phone 503.612.2300 fax

www.v-infinity.com

fax 503.612.2383

PART NUMBER: VHK75W

9. 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 4: TRIM-UP VOLTAGE SETUP

FIGURE 5: TRIM-DOWN VOLTAGE SETUP

The value of R

The value of R

Where: R

Where: R

nominal output voltage. V

nominal output voltage. V

For example, to trim-up the output voltage of 5.0V module

For example, to trim-down the output voltage of 5.0V module

(VHK75W-Q48-S5) by 8% to 5.4V, R

(VHK75W-Q48-S5) by 8% to 4.6V, R

as follows:

as follows:

R load

10K

Ω

Trimpot

+Vin

-Vin

-Vo

-S

Trim

+S

+Vo

R load

R trim-up

+Vin

-Vin

+Vo

+S

Trim

-S

-Vo

R load

R trim-down

+Vin

-Vin

+Vo

+S

Trim

-S

-Vo

FIGURE 3. TRIMMING WITH

EXTERNAL POTENTIOMETER

R2 = 8.2 KΩ

R1 = 5.8 KΩ

o

o, nom = 5.4 - 5.0 = 0.4 V

V - V

=

= 6.3 (KΩ)

R

0.4

trim-up

5.8 - 8.2 x 0.4

V

- V

=

= 3.98 (KΩ)

R

0.4

trim-down

5.8 - 10.52 x 0.4

R2 = 10.52 KΩ

R1 = 5.8 KΩ

o

o, nom

= 5.0 - 4.6 = 0.4 V

=

(KΩ)

R

o

o, nom

V - V

o

o, nom

trim-up

R1 - R2 x (V - V

)

=

(KΩ)

R

o

o, nom

V

- V

o

o, nom

trim-down

R1 - R2 x (V

- V )

13.0476

74.514

48V

16.67

14.76

13.304

8.2

7.2

42.33

25.474

19.656

5.8

3.168

24V

15V

12V

5V

3.3V

Table 1

295.527

1569.6

48V

120

94

60.1

10.52

15

430

150

86.45

5.8

6.18

24V

15V

12V

5V

3.3V

Table 2