URA2405LD-20WR3_15 Datasheet, PDF (5/9 Pages) MORNSUN Science& Technology Ltd. – DC/DC Converter

DC/DC Converter
URA_LD-20WR3 & URB_LD-20WR3 Series
EMC solution-recommended circuit PCB layout
Fig. 4
Note: the min. distance of the bonding pads between input & output isolation capacitors (CY1/CY2) shall be ≥ 2mm.
3. Application of Trim and calculation of Trim resistance
+Vot
+Vot
R1
Vref ^R3
R2
RT
Tri m
R1
Vref ^R3
R2
RT
Tri m
0V
Trim up
0V
Trim down
Applied circuits of Trim (Part in broken line is the interior of models)
Calculation formula of Trim resistance:
up: RT=
aR2
R2-a
-R3
down: RT=
aR1
R1-a
-R3
Vr e f
a= _{Vo’-Vref} R1
a= ^{Vo’-Vref} R2
Vr e f
RT is Trim resistance
a is a self-defined parameter, with
no real meaning.
Vout(V)
3.3
5
9
12
15
24
R1(KΩ)
4.801
2.883
7.500
11.000
14.494
24.872
R2(KΩ)
2.87
2.87
2.87
2.87
2.87
2.87
R3(KΩ)
12.4
10
15
15
15
17.8
Vref(V)
1.25
2.5
2.5
2.5
2.5
2.5
4. It is not allowed to connect modules output in parallel to enlarge the power
5. For more information please find DC-DC converter application notes on www.mornsun-power.com
2015.09.28-A/3
Page 5 of 9
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