EP3003 Datasheet, PDF (9/12 Pages) Eorex Corporation – 2-CH, 600mA Synchronous Step-down Converter

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:
( ) _{L =} V_OUT × V_IN −V_OUT
V_IN × ΔI _L × f_OSC
where ΔI_L is inductor Ripple Current. Choose inductor ripple current approximately 35% of the
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
1.4
56.2
2.52
CR43
2.2
71.2
3.3
86.2
1.75
4.5x4.0x3.5
1.44
4.7
108.7
1.15
Sumida
1.5
CDRH4D18 2.2
75
3.3
110
1.32
4.7x4.7x2.0
1.04
4.7
162
0.84
Toko
1.5
120
1.29
D312C
2.2
140
3.3
180
1.14
3.6x3.6x1.2
0.98
4.7
240
0.79
Rev.01
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