Datasheet

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CUI Inc │ SERIES: VHK50W │ DESCRIPTION: DC-DC CONVERTER date 12/17/2013 │ page 8 of 9
APPLICATION NOTES
1. Output Voltage Trimming
Leave open if not used.
Table 4
Vout
(Vdc)
R1
(K)
R2
(K)
R3
(K)
Vr
(V)
Vf
(V)
3.3 3 12 18 1.24 0.46
5 2.32 8.2 0 2.5 0
12 9.1 51 18 2.5 0.46
15 12 82 18 2.5 0.46
24 20 100 20 2.5 0.46
28 23.7 150 16 2.5 0.46
48 36 270 14 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 down
R1(Vr - Vf ( ))
Rtrim - up = ( ) - (KΩ)
R
trim - down = - R2 (KΩ)
Vo - Vo, nom
R2
R2 + R3
R2 + R3
R2R3
R1(Vo - Vr)
Vo, nom - Vo
Note: R
trim-up
is the external resistor in K
R
trim-down
is the external resistor in K
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).
Figure 7
Formula for Trim ResistorApplication Circuit for Trim pin
Note: 1. All specifi cations are measured at Ta=25°C, nominal input voltage and full output load unless otherwise specifi ed.
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