MS1003SH･MS1004SH

Application Note Ver.2.2

SHINDENGEN ELECTRIC MFG. CO. , LTD

19/41

5.2 Example of main transformer design conditions

The values below are provided as guideline values only. Make the appropriate adjustments to suit specific

load conditions.

Description

Symbol

Unit

Reference value

Input voltage range

[V]

85–276

Efficiency



-

0.80–0.85

Minimum oscillation frequency

[kHz]

35–50

On duty ratio

D

-

0.4–0.6

Capacity of resonating capacitor

Cq

[pF]

100–3300

Control coil voltage

[V]

15–20

Magnetic flux density variation

B

[mT]

250–300

Coil current density



[A/mm

4–6

* If the output capacity of the main switching device Coss is significant relative to the

capacity setting of the resonating capacitor, Cq must be the capacity of the resonating

capacitor plus Coss.

5.3 Formulas for main transformer design

1

Minimum DC input

voltage

(min)

(min)

2

.

1

AC

DC

V

V





[V]

2

Maximum DC input

voltage

(max)

(max)

2

AC

DC

V

V





[V]

3

Maximum oscillation cycle

(min)

(max)

1

f

T



[s]

4

Maximum ON period

(min)

1

(max)

f

D

t

on



[s]

5

Maximum OFF period

tq

V

V

Np

t

V

N

t

F

O

on

DC

S

off













)

(

1

1

1

(max)

(min)

1

(max)

[s]

6

Quasi-resonance period

Cq

Lp

tq









[s]

7

Maximum load power

(max)

(max)

O

O

I

Vo

P





[W]

8

Maximum output power

(reference value)

(max)

2

.

1

O

L

P

P





[W]

9

Main SW device peak

current

D

V

P

I

DC

L

DP









(min)

2



[A]