PRF20 Datasheet, PDF (5/6 Pages) CUI INC – DC-DC CONVERTER

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CUI Inc │ SERIES: PRF20 │ DESCRIPTION: DC-DC CONVERTER
date 02/12/2014 │ page 5 of 6
APPLICATION NOTES
Output Voltage Trimming
Leave open if not used.
Figure 3
Application Circuit for Trim pin
+Vin
Trim up
-Vin
+Vin
Trim down
-Vin
+Vo
Trim
-Vo
+Vo
Trim
-Vo
R-Load
R trim-up
R trim-down
R-Load
Formula for Trim Resistor
Rtrim
-
up
=
(
Vr x
(Vo
R1 x
- Vo,
(R2 +
nom) x
R3)
R2
)
-
Rt
(KΩ)
Rtrim
-
down
=
R1
x
(
(Vo,
Vr
nom
x
-
R1
Vo)
x
R2
-1)
-
Rt
(KΩ)
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, Rt, and Vr are internal (see table 3).
Table 3
Vout
(Vdc)
5
12
15
R1
(KΩ)
2.32
6.8
8.06
R2
R3
Rt
Vr
(KΩ) (KΩ) (KΩ) (V)
2.32 0
8.2 2.5
2.4 2.32 22 2.5
2.4 3.9 27 2.5
Note:
1. All specifications are measured at Ta=25°C, nominal input voltage and full output load unless otherwise specified.
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