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

6

ISOLATED DC/DC CONVERTERS

48 Vdc Input

1.2 Vdc /50 A Output

Aug. 10, 2010

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

Output Trim Equations

Equations for calculating the trim resistor are shown below. The Trim Down resistor should be connected

between the Trim pin and Sense(-) pin. The Trim Up resistor should be connected between the Trim pin and the

Sense(+) pin. Only one of the resistors should be used for any given application.

Connecting an external resistor between the TRIM pin and the Sense (-)

pin decreases the output voltage set point.

Connecting an external resistor between the TRIM pin and the Sense (+)

pin increases the output voltage set point.

Note:

Vo_req=Desired (trimmed) output voltage [V]

Output voltage Vo=1.2 V

Remote sense minimizes the effects of distribution losses by regulating the voltage at the remote-sense

connections. The voltage between the remote-sense pins and the output terminals must not exceed the

output voltage sense range:

≤ 10% x Vout. If not using the remote-sense feature to regulate the output

voltage at the point of load, connect SENSE (+) to Vout and SENSE (-) to GND at the module. The tracks,

that connect the sense pins to the load, must have a resistance << than 10 ohm (for example maximum

100 mOhm).

[]

Ω

−

=

k

delta

Rtrimdown

22

.

10

511

Module

Vout

Trim

GND

Rtrimdown

[]

(100

)

5.11

511

10.22

0.6125

delta Vo

Rtrimup

k

delta

delta

+⋅

⋅

=−

−

Ω

⋅

Module

Vout

Trim

GND

Rtrimup

()

[]

%

100

_

×

−

=

Vo

Vo

req

Vo

delta

0.96

0.98

1.01

1.03

1.06

1.08

1.1

1.13

1.15

1.18

1.2

0

40

80

120

160

200

240

280

320

360

400

Adjusted output voltage Vo,adj (V)

1.2

1.21

1.22

1.24

1.25

1.26

1.27

1.28

1.3

1.31

1.32

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Adjusted output voltage Vo,adj(V)