Bel Fuse Inc.

206 Van Vorst Street, Jersey City, NJ 07302

• Tel 201-432-0463 • Fax 201-432-9542 • www.belfuse.com

NON-ISOLATED DC/DC CONVERTERS

2.4 Vdc - 5.5 Vdc Input

0.75 Vdc - 3.63 Vdc/3 A Output

Output Trim Equations

A

: Equation for calculating the trim resistor (in kΩ) given the desired adjusted voltage (Vadj) is shown below.

The Trim Up resistor should be connected between the Trim pin and Ground.

Table 1

Vadj (V)

Rtrim (KΩ)

0.7525

Open

1.2

41.973

1.5

23.077

1.8

15.004

2.0

11.779

2.5

6.947

3.3

3.16

B

. Equation for calculating the trim voltage (in V) given the desired adjusted voltage (Vadj) is shown below. The

Trim Up voltage should be connected between the Trim pin and Ground.

Table 2

Vadj (V)

Vtrim (V)

0.7525

Open

1.2

0.624

1.5

0.5731

1.8

0.5221

2.0

0.4882

2.5

0.4033

3.3

0.267

C.

Vtrim

Module

Vout

GND

Trim

0.75 1.04 1.33 1.61 1.9 2.19 2.48 2.77 3.05 3.34 3.63

0

20

40

60

80

100

120

140

160

180

200

Rtrim vs.Output Voltage

Output Voltage(V)

0.75 1.04 1.33 1.61

1.9

2.19 2.48 2.77 3.05 3.34 3.63

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

Vtrim vs. Output Voltage

Vo(V)

Rtrim

Module

Vout

GND

Trim

V

O

T

rim

GND

R

down

R

up

R

set

Vm_up: Margin up value after output voltage is set with Rset

11

.

5

7525

.

0

07

.

21

−

−

=

adj

trim

V

R

)

7525

.

0

(

1698

.

0

7

.

0

−

×

−

=

adj

trim

V

V

Vm_down: Margin down value after output voltage is set with Rset

Note:

Output voltage Vo=0.7525 V when Trim pin is not connected.

Rup

21.07 Rset

⋅

5.11 Vm_up

⋅

Rset

⋅

−

3.845 Rset

⋅

+

Vm_up Rset

⋅

5.11 Vm_up

⋅

+

0.753Rset

−

24.915

−

Rdown

5.978 Vm_down

⋅

Rset

⋅

4.230 Rset

⋅

−

0.128 Rset

⋅

0.868 Vm_down

⋅

−

0.170 Vm_down

⋅

Rset

⋅

−

4.230

+

Rset

21.07

Vo

0.7525

−

5.11

−

Vm_down 90%Vo

≥

KΩ

KΩ

KΩ