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DS_E48SR1R825_05222008
10
FEATURES DESCRIPTIONS (CON.)
Output Voltage Adjustment (TRIM)
To increase or decrease the output voltage set point,
connect 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. 26). The external resistor value
required to obtain a percentage of output voltage
change △% is defined as:
()
Ω
⎥
⎦
⎤
⎢
⎣
⎡
−
Δ
=− KdownRtrim 2.10
511
Ex. When Trim-down -10%(1.8V×0.9=1.62V)
() ()
Ω=Ω
⎥
⎦
⎤
⎢
⎣
⎡
−=− KKdownRtrim 9.402.10
10
511
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. 27). The external resistor value required to obtain
a percentage output voltage change △% is defined
as:
()
Ω−
Δ
−
Δ
Δ+
=− KupRtrim 2.10
511
1.225
) (100 Vo11.5
Ex. When Trim-up +10%(1.8V×1.1=1.98V)
()
Ω=−−
×
+
×
×
=− KupRtrim 29.212.10
10
511
101.225
) 10(100 8.111.5
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.