Fujitsu MB39A104 Manual

A SERVICE OF

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MB39A104

27

Example:

CH1

CH2

Inductance values derived from the above formulas are values that provide sufficient margin for continuous

operation at maximum load current, but at which continuous operation is not possible at light loads. It is therefore

necessary to determine the load level at which continuous operation becomes possible. In this application, the

Sumida CDRH104R-150 is used. At 15 µH, the load current value under continuous operating conditions is

determined by the following formula.

Load current value under continuous operating conditions : I

O

Example: Using the CDRH104R-150

15 µH (allowable tolerance ±30%) , rated current = 3.6 A

CH1

CH2

L ≥

2 (V

IN − VO)

ton

I

O

≥

2 × (19 − 5)

×

1

× 0.263

IO 500 × 10

3

≥ 4.91 µH

L ≥

2 (VIN − VO)

ton

I

O

≥

2 × (19 − 3.3)

×

1

× 0.174

IO 500 × 10

3

≥ 3.64 µH

IO ≥

VO

toff

2L

I

O ≥

VO

toff

2L

≥

5

×

1

× (1 − 0.263)

2 × 15 × 10

−6

500 × 10

3

≥ 245.7 mA

IO ≥

VO

toff

2L

≥

3.3

×

1

× (1 − 0.174)

2 × 15 × 10

−6

500 × 10

3

≥ 181.7 mA