Technical Reference Note
Trim Characteristics
Rev.02.06.15_#1.2
AVO75B-36S3V3
Page 21
Connecting an external resistor between Trim pin and Vo- pin will decrease the output voltage. While connecting it
between Trim and Vo+ will increase the output voltage. The following equations determine the external resistance to obtain
the trimmed output voltage.
510
Radj−down
=
−10.2(KΩ)
∆
5.1×Vnom
×
100+ ∆
510
Radj−up
=
−
−10.2(KΩ)
1.225× ∆
∆
△:Output e rate against nominal output voltage.
100× (Vnom −V0 )
∆ =
Vnom
Vnom: Nominal output voltage.
For example, to get 3.65V output, the trimmingresistor is
100× (Vnom −V0 )
100× (3.63 − 3.3)
∆ =
=
= 10
Vnom
3.3
5.1×3.3×
100 +10
510
10
Radj−up
=
−
−10.2 = 89.9(KΩ)
1.225×10
The output voltage can also be trimmed by potential applied at the Trim pin
VO = (Vtrim +1.225)×1.347
Where Vtrim is the potential applied at the Trim pin, and Vo is the desired output voltage. When trimming up, the output
current should be decreased accordingly so as not to exceed the maximum output power.
Figure 24 Trim up
Figure 25 Trim down
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