LTC3563

13

3563f

With this information we can calculate L using:

L

fI

V

V

V

L

OUT

OUT

IN

=

⎛

⎝⎜

⎞

⎠⎟

1

1

•

••

–

∆

f = 2.25MHz gives:

L

V

MHz

mA

V

V

=

⎛

⎝⎜

⎞

⎠⎟

=

187

2 25

200

1

187

42

231

.

.•

•–

.

.

. µ

µH

With V

V

L

V

MHz

mA

=

128

128

2 25

200

1

12

.

.

.•

•–

. 8

8

42

198

V

V

µH

.

.

⎛

⎝⎜

⎞

⎠⎟

=

Choosing a vendor’s closest inductor value of 2.2µH results

in a maximum ripple current of:

For V

V

I

V

MHz

µH

V

OUT

L

=

=

187

187

225

22

1

187

.

.

.• .

•–

.

∆

4

42

209 6

128

128

2

.

.

.

.

.

V

mA

For V

V

I

V

OUT

L

⎛

⎝⎜

⎞

⎠⎟

=

=

=

∆

2

25

2 2

1

128

42

179 8

MHz

µH

V

V

mA

•.

•–

.

.

.

⎛

⎝⎜

⎞

⎠⎟

=

APPLICATIO S I FOR ATIO

Hot Swap is a trademark of Linear Technology Corporation.

ESR of less than 0.2Ω. In most cases, ceramic capacitors

Figure 3 shows the complete circuit along with its efficiency

curve, load step response and recommended layout.

PC Board Layout Checklist

When laying out the printed circuit board, the following

checklist should be used to ensure proper operation of

the LTC3563. These items are also illustrated graphically

in Figure 3b. Check the following in your layout:

1. The power traces, consisting of the GND trace, the SW

wide.

possible? This capacitor provides the AC current to the

internal power MOSFETs.

Figure 3a. Typical Application

LTC3563

RUN

3563 F03

L

SW

2.7V TO 5.5V

GND

1.28V 1.87V