Rainbow Electronics MAX8621Z - Manual (Page 13)

Inductor Selection
The MAX8621Y/MAX8621Z step-down converters oper-
ate with inductors between 1µH and 4.7µH. Low-induc-
tance values are physically smaller but require faster
switching, resulting in some efficiency loss. See the
Typical Operating Characteristics for efficiency and
switching frequency vs. inductor value plots. The
inductor’s DC current rating needs to be only 100mA
greater than the application’s maximum load current
because the step-down converter features zero-current
overshoot during startup and load transients.
For output voltages above 2.0V, when light-load effi-
ciency is important, the minimum recommended induc-
tor is 2.2µH. For optimum voltage-positioning load
transients, choose an inductor with DC series resis-
tance in the 50m
Ω to 150mΩ range. For higher efficien-
cy at heavy loads (above 200mA) or minimal load
regulation (but some transient overshoot), the resis-
tance should be kept below 100m
Ω. For light-load
applications up to 200mA, much higher resistance is
acceptable with very little impact on performance. See
Table 2 for some suggested inductors.
MAX8621Y/MAX8621Z
Dual Step-Down DC-DC Power-Management ICs
for Portable Devices
______________________________________________________________________________________ 13
MANUFACTURER SERIES
INDUCTANCE
(µH)
ESR
( Ω)
CURRENT RATING
(mA)
DIMENSIONS
CB2012
2.2
4.7 0.23
0.40 410
300 2.0 x 1.25 x 1.25
= 3.1mm 3
LB2012
1.0
2.2 0.15
0.23 300
240 2.0 x 1.25 x 1.25
= 3.1mm 3
LB2016
1.0
1.5
2.2
3.3 0.09
0.11
0.13
0.20 455
350
315
280
2.0 x 1.6 x 1.8
= 5.8mm 3
LB2518
1.0
1.5
2.2
3.3 0.06
0.07
0.09
0.11 500
400
340
270
2.5 x 1.8 x 2.0
= 9mm 3
Taiyo Yuden
LBC2518
1.0
1.5
2.2
3.3
4.7 0.08
0.11
0.13
0.16
0.20 775
660
600
500
430
2.5 x 1.8 x 2.0
= 9mm 3
LQH32C_53
1.0
2.2
4.7 0.06
0.10
0.15 1000
790
650
3.2 x 2.5 x 1.7
= 14mm 3
Murata
LQM43FN
2.2
4.7 0.10
0.17 400
300 4.5 x 3.2 x 0.9
= 13mm 3
D310F
1.5
2.2
3.3 0.13
0.17
0.19 1230
1080
1010
3.6 x 3.6 x 1.0
= 13mm 3
TOKO
D312C
1.5
2.2
2.7
3.3 0.10
0.12
0.15
0.17 1290
1140
980
900
3.6 x 3.6 x 1.2
= 16mm 3
Sumida CDRH2D11
1.5
2.2
3.3
4.7 0.05
0.08
0.10
0.14 900
780
600
500
3.2 x 3.2 x 1.2
= 12mm 3
Table 2. Suggested Inductors