PDQ30-Q24-S3-D Datasheet, PDF (8/9 Pages) CUI INC – DC-DC CONVERTER

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CUI Inc │ SERIES: PDQ30-D │ DESCRIPTION: DC-DC CONVERTER
date 07/12/2016 │ page 8 of 9
APPLICATION NOTES
Output Voltage Trimming
The output voltage can be adjusted (single outputs only) by using the trim pin and the use of either an external trim pot or
the use of a single fixed resistor (see Figures below). If the trim function is not needed, leave the trim pin open.
Figure 4 Trim Adjustments Using
A Trimpot
Figure 5 Trim Adjustments To Increase
Output Voltage Using A Fixed Resistor
Figure 6 Trim Adjustments To Decrease
Output Voltage Using A Fixed Resistor
+Vin
-Vin
+Vo
Trim
-Vo
10 kΩ
Trimpot
R-Load
+Vin
-Vin
+Vo
Trim
-Vo
R trim-up
R-Load
+Vin
-Vin
+Vo
Trim
-Vo
R trim-down
R-Load
Formula for Trim Resistor
Rtrim up (^{Vr R1 (R2 R3)} ) Rt (k )
(Vo Vo, nom ) R 2
Rtrim down R1 (
Vr R1
1) Rt (k )
(Vo, nom Vo) R2
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 4)
Table 4
Output
Voltage
(Vdc)
3.3
5
12
15
R1
(kΩ)
2.74
2.32
6.8
8.06
R2
(kΩ)
1.8
2.32
2.4
2.4
R3
(kΩ)
0.27
0
2.32
3.9
Rt
(kΩ)
9.1
8.2
22
27
Vr
(V)
1.24
2.5
2.5
2.5
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