ZSLS7025 Datasheet

© 2016 Integrated Device Technology, Inc.

22

April 20, 2016

η

×

×

×

=

×

=

IN

OUT

OUT

AVG

_

IN

PEAK

_

IN

V

I

V

5

.

1

I

5

.

1

I

A

95

.

1

9

.

0

12

35

.

0

40

5

.

1

≈

×

×

×

=

Ω

=

=

123

.

0

I

V

R

PEAK

_

IN

TH

_

CS

CS

A

3

.

1

V

I

V

I

IN

OUT

OUT

AVG

_

IN

=

η

×

×

=

(

)

A

3

.

1

I

I

2

I

AVG

_

IN

PEAK

_

IN

RIPPLE

=

−

×

=

(

)

s

5

.

2

R

R

R

I

V

)

L

I

(

t

CS

)

ON

(

DS

L

AVG

_

IN

IN

1

RIPPLE

ON

µ

≈

+

+

×

−

×

=

1µs

V

)

R

(I

V

V

L

I

t

IN

L

IN_AVG

D

OUT

1

RIPPLE

OFF

>

−

×

+

+

×

=

(

)

kHz

285

t

t

1

'

f

OFF

ON

≈

+

=

4.4.5

Assume that

(21)

Where

η is the assumed power conversion efficiency (the recommended value for this calculation is 0.9)

(22)

 Choose R

0.123Ω, I

4.4.6

Input average current:

(23)

(24)

(25)

22μH.

22μH and R

=0.4Ω

(26)

Then the assumed switching frequency:

(27)