URF_LP-20WR3_15 Datasheet, PDF (4/6 Pages) MORNSUN Science& Technology Ltd. – DC/DC Converter

DC/DC Converter
URF_LP-20WR3 Series
Vin
Cin
GND
DC DC
Fig. 2
+Vo
Cout
0V
2. EMC solution-recommended circuit
V in
GND
FU SE
M OV
+
C0
①
LDM 1
C1
②
C Y1
Vin
+Vo
D C/ D C
C2
GND
0V
C Y2
C3 ^LOAD
Fig. 3
Notes: Part ① in the Fig. 3 is used for EMS test and part ② for EMI filtering;
selected based on needs.
EMC solution-recommended circuit PCB layout
Vin(VDC)
3.3/5
9/12/15
24
Cout(µF)
470
220
100
Cin(µF)
100
Parameter description
Model
Vin:24V
Vin:48V
FUSE
Choose according to actual input current
MOV
S14K35
S14K60
C0
330µF/50V
330µF/100V
C1/C2
C3
1µF/50V
1µF/100V
Refer to the Cout in Fig.2
LDM1
6.8mH
CY1
1nF/3KV
CY2
1nF/3KV
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}
Vr e f
R2
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
2015.08.12-A/2
Page 4 of 6
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