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Revision 1.04

12 - 20

AS1390A, AS1390B

Datasheet - D e t a i l e d D e s c r i p t i o n

8.1.3

Continuous Conduction Mode (CCM)

Where:

8.1.4

Duty Cycle

Within CCM, the well known relation between input and output voltage is described in the following equation:

this means for the duty cycle:

8.1.5

Inductor Current

The inductor current varies during a switching cycle. This variation can be expressed by the mean value of the inductor current and the delta rise/

fall current within each cycle (see Figure 21).

Figure 21. Inductor Current

Mean inductor current:

Delta inductor current:

(EQ 5)

L

C RIT

1

V

IN

V

OUT

V

D

+

---------------------------

–









V

2

IN

×

R

×

2

f

SW

×

V

OUT

V

D

+

(

)

2

×

----------------------------------------------------------------------

=

(EQ 6)

V

OUT

V

D

+

V

IN

---------------------------

1

1

D

–

-------------

=

(EQ 7)

D

1

V

IN

V

OUT

V

D

+

---------------------------

–

=

(EQ 8)

I

L

I

OUT

1

D

–

-------------

=

(EQ 9)

I

L

∆

D

V

IN

×

f

S

L

×

-------------------

=