Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302

6

ISOLATED DC/DC CONVERTERS

48 Vdc Input 12 Vdc/12 A, 3.3 Vdc/46 A, 5 Vdc/30 A, 1.2-2.5 Vdc/50 A Outputs

May 17, 2011

Bel Power Inc., a subsidiary of Bel Fuse Inc.

Output Trim Equations

Trim Resistor Calculate

Equations for calculating the trim resistor are shown below

(Unit: kΩ). The Trim Down resistor should be

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

pin and the Vout. Only one of the resistors should be used for any given application.

1) For Vo=1.5 V – 12 V:

Note

:

Vo_req=Desired (trimmed) output voltage [V]; Vo=output voltage

Vo=12.006 V for 12 V output; Vo=5.000 V for 5 V output; Vo=3.308 V for 3.3 V output; Vo=2.505 V for 2.5 V

output; Vo=1.804 V for 1.8 V output; Vo=1.503 V for 1.5 V output

2) For Vo=1.2 V:

Note

:

Vo_req=Desired (trimmed) output voltage [V]; Vo=output voltage

Vo=1.202 V for 1.2 V output

22

.

10

225

.

1

626

11

.

5

)

100

(















delta

Vo

delta

Rtrimup

22

.

10

511 



delta

Rtrimdown





 

%

100

_







Vo

Vo

req

Vo

delta

Module

Vout

Trim

GND

Rtrimdown

Module

Vout

Trim

GND

Rtrimup

22

.

10

6125

.

0

313

11

.

5

)

100

(















delta

Vo

delta

Rtrimup

22

.

10

511 



delta

Rtrimdown





 

%

100

_







Vo

Vo

req

Vo

delta