AC/DC Converter

LH20(25) Series

2015.08.24-B/3

Page 5 of 8

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2. EMC solution-recommended circuit

ACDC

AC(N)

AC(L)

LCM

MOV1 CX

CY1

CY2

FUSE

AC(N)

AC(L)

+Vo

-Vo

+

LDM

C1

C2

TVS1

RL

Can use MORNSUN s FC-LX1D

'

Fig 5: EMC Recommended circuit with higher requirements

Element

model

Recommended value

MOV1

S14K300

CY1 , CY2

1000pF/400VAC

CX

0.1μF/275VAC

LCM

10mH, recommended to use MORNSUN’s FL2D-Z5-103

LDM

4.7μH/2A

FC-LX1D

2KV/4KV EMC filter

FUSE

3.15A/250V slow fusing, necessary

3. Application of Trim and calculation of Trim resistance

0V

Trim

+Vot

0V

Trim

+Vot

Trim up

Trim down

Applied circuits of Trim (Part in broken line is the interior of models):

Calculation formula of Trim resistance:

up:

a=

Vref

Vot-Vref

R =

T

R -a

2

down:

a=

Vref

Vot-Vref

R =

T

R -a

1

a is a self-defined parameter, with

no real meaning.

Vout

R1(KΩ)

R2(KΩ)

R3(KΩ)

Vref(V)

Vot(V)

3.3V

3.3

1.98

1

1.24

Output voltage

after regulation,

variation ≤ ±10%

5V

3.3

3.3

1

2.5

9V

7.5

2.87

1

2.5

12V

3.83

1

1

2.5

15V

7.5

1.5

1

2.5

24V

8.66

1

1

2.5

48V

68

3.73

1

2.5

download the Selection Guide of EMC Filter