H48SC3R325_07122011

9

FEATURES DESCRIPTIONS (CON.)

Output Voltage Adjustment (TRIM)

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

SENSE(+) or SENSE(-). The TRIM pin should be left

open if this feature is not used.

Figure 18: Circuit configuration for trim-down (decrease

output voltage)

If the external resistor is connected between the TRIM

and SENSE (-) pins, the output voltage set point

decreases (Fig. 18). The external resistor value

required to obtain a percentage of output voltage

change △% is defined as:

Rtrim down=

100

∆

2

−









ΚΩ

Ex. When Trim-down 10% (3.3V×0.9=2.97V)

Vo

3.3

:=

V

∆

10

:=

100

∆

2

−

8

=

K

Ω

Figure 19: Circuit configuration for trim-up (increase output

voltage)

If the external resistor is connected between the TRIM

and SENSE (+) the output voltage set point increases

(Fig. 19). The external resistor value required to obtain

a percentage output voltage change △% is defined

as:

Rtrim up= Vo 100

∆

+

(

)

⋅

1.225

∆

⋅

100

2

∆

+

∆

−













ΚΩ

Ex. When Trim-up +10%(3.3V×1.1=3.63V)

Vo

3.3

:=

V

∆

10

:=

Vo

100

∆

+

()

⋅

1.225

∆

⋅

100

2

∆

⋅

+

∆

−

17.633

=

K

Ω

The output voltage can be increased by both the remote

sense and the trim, however the maximum increase is

the larger of either the remote sense or the trim, not the

sum of both.

When using remote sense and trim, 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.