Delta Electronics S48SE Datasheet page 8

FEATURES DESCRIPTIONS (CON.)
Output Voltage Adjustment
To increase or decrease the output voltage set point,
the modules may be connected with an external
resistor between the TRIM pin and either the Vo(+) or
Vo(-). The TRIM pin should be left open if this feature
is not used.
Vo (-) Vo (-) Vo (-)
ON/OFF ON/OFF ON/OFF
Trim Trim Trim
Vi (-) Vi (-) Vi (-)
Vi (+) Vi (+) Vi (+)
Vo (+) Vo (+) Vo (+)
Figure 17: Circuit configuration for trim-down (decrease
output voltage)
If the external resistor is connected between the TRIM
and Vo(+) pins, the output voltage set point decreases
(Fig. 17). The external resistor value required to obtain
an output voltage change from 5V to the desired
Vo_adj is defined as:
−
( Vo_adj 2.5
Rtrim_down
−
5.0 Vo_adj
Ex. When Trim-down -10%
Vo_adj=5.0V×(1-10%)=4.5V
− ⋅
( 4.5 2.5 ) 5110
Rtrim_down
−
5.0 4.5
4
= ×
Rtrim_down 1.839 10 ohm
DS_S48SE05003_12292006
R R
Load Load
R R R
trim-down trim-down trim-down
⋅
) 5110
−
2050
−
2050
ON/OFF ON/OFF
Vo (-) Vo (-)
Vi (-) Vi (-)
Trim Trim
Vi (+) Vi (+)
Vo (+) Vo (+)
Figure 18: Circuit configuration for trim-up (increase output
voltage)
If the external resistor is connected between the TRIM
and Vo(-) the output voltage set point increases (Fig.
18). The external resistor value required to obtain an
output voltage change from 5V to the desired Vo_adj is
defined as:
⋅
2.5 5110
−
Rtrim_up
−
Vo_adj 5.0
Ex. When Trim-up +10%
Vo_adj=5.0V×(1+10%)=5.5V
⋅
2.5 5110
−
Rtrim_up 2050
−
5.5 5.0
4
= ×
ohm
Rtrim_up 2.35 10
When using trim function, the output voltage of the
module is usually increased, which increases the power
output of the module with the same output current.
Care should be taken to ensure that the maximum
output power of the module remains at or below the
maximum rated power.
R R
trim-up trim-up
R R
Load Load
2050
8