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.
Vout
511
Rtrimdown =
−10.22[kΩ
]
delta
Module
Module
Trim
GND
Rtrimdown
Rtrimup
Connecting an external resistor between the TRIM pin and the Sense (-)
pin decreases the output voltage set point.
(100 + delta) ⋅Vo⋅5.11 511
Vout
Trim
GND
Rtrimup =
−
−10.22 kΩ
[ ]
delta
0.6125⋅delta
Connecting an external resistor between the TRIM pin and the Sense (+)
pin increases the output voltage set point.
Note:
(
Vo _ req −Vo
)
delta =
×100
[%]
Vo
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).
5000
400
360
320
280
240
200
4500
4000
3500
3000
2500
2000
1500
1000
500
160
120
80
40
0
0
0.96 0.98 1.01 1.03 1.06 1.08
1.1 1.13 1.15 1.18
1.2
1.2 1.21 1.22 1.24 1.25 1.26 1.27 1.28 1.3 1.31 1.32
Adjusted output voltage Vo,adj(V)
Adjusted output voltage Vo,adj (V)
Bel Fuse Inc. 206 Van Vorst Street, Jersey City, NJ 07302 • Tel 201-432-0463 • Fax 201-432-9542 • www.belfuse.com
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