Datasheet

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CUI Inc │ SERIES: VHK100W │ DESCRIPTION: DC-DC CONVERTER date 12/16/2013 │ page 7 of 8
APPLICATION NOTES
1. Output Voltage Trimming
Leave open if not used.
Table 4
Vout
(Vdc)
R1
(KΩ)
R2
(KΩ)
R3
(KΩ)
Vr
(V)
Vf
(V)
3.3 3 12 4.3 1.24 0.46
5 2.32 3.3 0 2.5 0
12 9.1 51 5.1 2.5 0.46
15 12 56 8.25 2.5 0.46
24 20 100 7.5 2.5 0.46
28 23.7 150 6.2 2.5 0.53
48 36 270 5.1 2.5 0.46
+Vin
R trim-up
R-Load
Trim
+Vo
+Sense
+Sense
-Sense
-Sense
-Vin
-Vo
Trim up
+Vin
-Vin
-Vo
+Vo
R trim-down
R-Load
Trim
Trim dow
n
R1(Vr - Vf ( ))
Rtrim - up = ( ) - (KΩ)
R
trim - down = - R2 (KΩ)
Vo - Vo, nom
R
2
R2 + R3
R2 + R3
R2R3
R1(Vo - Vr)
V
o, nom
- V
o
Figure 5
Formula for Trim ResistorApplication Circuit for Trim pin
Note: 1. All specications are measured at Ta=25°C, nominal input voltage and full output load unless otherwise specied.
Note: R
trim-up
is the external resistor in KΩ
R
trim-down
is the external resistor in KΩ
V
O, nom
is the nominal output voltage
V
O
is the desired output voltage
R1, R2, R3, and Vr are internal (see Table 4).
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