Datasheet

LTC3589/LTC3589-1/
LTC3589-2
27
3589ff
For more information www.linear.com/3589
Table 11. Inductors for Buck-Boost Switching Regulator
MANUFACTURERS
PART
NUMBER
VALUE
(µH) DCR ()
MAX DC
CURRENT (A) SIZE (mm) W × L × H
Coilcraft XFL4020-152ME
XFL4020-222ME
XFL4020-332ME
LPS6225-332ML
LPS6225-472ML
1.5
2.2
3.3
3.3
4.7
0.014
0.021
0.035
0.055
0.065
4.10
3.10
2.70
3.50
3.00
4.0 × 4.0 × 2.1
4.0 × 4.0 × 2.1
4.0 × 4.0 × 2.1
6.0 × 6.0 × 2.0
6.0 × 6.0 × 2.0
Cooper SD14-1R5-R
SD14-2R0-R
SD14-2R5-R
SD14-3R2-R
SD25-3R3-R
1.5
2.0
2.5
3.2
3.3
0.039
0.045
0.060
0.066
0.038
2.91
2.56
2.29
2.00
2.21
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
4.8 × 4.8 × 2.5
Sumida CDRH5D16NP-3R3N
CDRH5D16NP-4R7N
3.3
4.7
0.045
0.064
2.60
2.05
5.6 × 5.6 × 1.8
5.6 × 5.6 × 1.8
TDK VLF5014ST-2R2N2R3
VLCF5020T-2R7N2R2-1
VLCF5020T-3R3N2R0-1
2.2
2.7
3.3
0.073
0.083
0.096
2.3
2.2
2
4.8 × 4.6 × 1.4
5.0 × 5.0 × 2.0
5.0 × 5.0 × 2.0
TOKO 1124BS-1R8N
1124BS-3R3N
1.8
3.3
0.056
0.074
2.70
2.10
4.5 × 4.7 × 1.8
4.5 × 4.7 × 1.8
Tokin H-DI-0520-3R3
H-DI-0630-3R8
3.3
3.8
0.062
0.040
2.00
2.00
5.3 × 5.3 × 2.0
6.3 × 6.3 × 3.0
Wurth 744052002
7440420027
744053003
7440530047
2.5
2.7
3.0
4.7
0.030
0.047
0.024
0.030
2.4
2.2
2.8
2.4
5.8 × 5.8 × 1.8
4.8 × 4.8 × 1.8
5.8 × 5.8 × 2.8
5.8 × 5.8 × 2.8
Inductor Selection
Inductor selection criteria for the buck-boost are similar to
those given for the step-down switching regulators. The
buck-boost converter is designed to work with inductors
in the range of 1µH to 3.3µH. For most applications use a
1.5µH inductor. Choose an inductor with a DC current rating
at least two times larger than the maximum load current to
ensure that the inductor does not saturate during normal
operation. If output short-circuit is a possible condition,
the inductor should be rated to handle the maximum peak
current specified for the buck-boost converter. Table 11
shows several inductors that work well with the LTC3589
buck-boost regulator.
Table 10. Buck-Boost Command Register Settings
COMMAND
REGISTER[BIT]
VALUE SETTING
SCR1[6] 0*
1
Continuous Mode
Burst Mode Operation
OVEN[3] 0*
1
Disable
Enable
SCR2[3]
LTC3589/LTC3589-1
0*
1
Wait for Output Below 300mV Before Enable
Enable Immediately
SCR2[3]
LTC3589-2
0*
1
Enable Immediately
Wait for Output Below 300mV Before Enable
* Denotes Default Power-On Value
operaTion