Applications information, Table 12. recommended inductors – Rainbow Electronics MAX8649 User Manual
Page 29
MAX8649
1.8A Step-Down Regulator with Differential
Remote Sense in 2mm x 2mm WLP
______________________________________________________________________________________
29
Applications Information
Inductor Selection
Calculate the inductor value (L
IDEAL
) using the follow-
ing formula:
This sets the peak-to-peak inductor current ripple to 1/4
the maximum output current. The oscillator frequency,
f
OSC
, is 3.25MHz, and the duty cycle, D, is:
Given L
IDEAL
, the peak-to-peak inductor ripple current
is 0.25 x I
OUT(MAX)
. The peak inductor current is 1.125
x I
OUT(MAX)
. Make sure that the saturation current of
the inductor exceeds the peak inductor current, and
the rated maximum DC inductor current exceeds the
maximum output current (
OUT(MAX)
). Inductance val-
ues smaller than L
IDEAL
can be used to reduce induc-
tor size; however, if much smaller values are used,
peak inductor current rises and a larger output capaci-
tance may be required to suppress output ripple.
Larger inductance values than L
IDEAL
can be used to
obtain higher output current, but typically require a
physically larger inductor size. See Table 12 for rec-
ommended inductors.
D
V
V
OUT
IN
=
L
V
D
D
I
f
IDEAL
IN
OUT MAX
OSC
=
Ч
Ч Ч
( )
Ч
(
)
4
1-
MANUFACTURER
SERIES
INDUCTANCE
(µH)
DC RESISTANCE
(
Ω typ)
CURRENT RATING
(mA)
DIMENSIONS
L x W x H (mm)
KSLI-2520AG
Multilayer
1.0
1.5
2.2
0.075
0.075
0.115
1800
1800
1400
2.5 x 2.0 x 1.0
Hitachi Metals
KLSI-2016AG
0.75
1.0
1.5
0.09
0.09
0.13
1500
1500
1100
2.0 x 1.6 x 1.0
FDK
MIPSA2520D
Multilayer
0.5
1.3
1.6
2.0
0.11
0.10
0.09
0.06
2000
2000
2000
2000
2.5 x 2.0 x 0.5
CKP3216
Multilayer
1.0
1.5
2.2
0.11
0.13
0.14
1100
1000
900
3.2 x 1.6 x 0.9
Taiyo Yuden
NR3015
1.0
1.5
0.03
0.04
2100
1800
3.0 x 3.0 x 1.5
TDK
VLS3015T
1.0
2.2
0.048
0.070
2000
1400
3.0 x 3.0 x 1.5
TOKO
DE2812C
0.56
1.2
1.5
2.0
0.032
0.044
0.050
0.067
2300
1800
1500
1400
3.2 x 3.0 x 1.2
LPS3008
0.56
0.80
1.0
1.5
2.2
0.072
0.092
0.125
0.134
1800
1600
1400
1150
3.0 x 3.0 x 0.8
Coilcraft
LPS3010
0.68
1.0
1.5
1.8
2.2
0.070
0.080
0.085
0.120
0.150
2300
1800
1600
1300
1200
3.0 x 3.0 x 1.0
Table 12. Recommended Inductors