Rev.01

9

EP3003

Inductor Selection

For most designs, the EP3003 operates with inductors of 1µH to 4.7µH. Low inductance values are

physically smaller but require faster switching, which results in some efficiency loss. Large value

inductors lower ripple current and small value inductors result in high ripple currents. The inductor value

can be derived from the following equation:

()

OSC

L

IN

OUT

IN

OUT

f

I

V

V

V

V

L

×

Δ

×

−

×

=

where

L

I

maximum load current 600mA, or 210mA.

For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended

inductor is 2.2µH. For optimum voltage-positioning load transients, choose an inductor with DC series

resistance in the 50mΩ to 150mΩ range. For higher efficiency at heavy loads (above 200mA), or minimal

load regulation (but some transient overshoot), the resistance should be kept below 100mΩ. The DC

current rating of the inductor should be at least equal to the maximum load current plus half the ripple

current to prevent core saturation (600mA+105mA). Table 1 lists some typical surface mount inductors

that meet target applications for the EP3003.

Part #

L (µH)

Max DCR (m.)

Rated D.C. Current (A)

Size WxLxH (mm)

Sumida

CR43

1.4

2.2

3.3

4.7

56.2

71.2

86.2

108.7

2.52

1.75

1.44

1.15

4.5x4.0x3.5

Sumida

CDRH4D18

1.5

2.2

3.3

4.7

75

110

162

1.32

1.04

0.84

4.7x4.7x2.0

Toko

D312C

1.5

2.2

3.3

4.7

120

140

180

240

1.29

1.14

0.98

0.79

3.6x3.6x1.2