LTC3589_12 Datasheet, PDF (24/50 Pages) Linear Technology – 8-Output Regulator with Sequencing and I2C

LTC3589/LTC3589-1/
LTC3589-2
OPERATION
BUCK-BOOST SWITCHING REGULATOR
Output Voltage Programming
Set the output voltage of the LTC3589 buck-boost switch-
ing regulator using an external resistor divider connected
from BB_OUT to the feedback pin BB_FB and to GND, as
shown in Figure 4.
V_{BB _ OUT}
=
0.8
•


¹⁺

RR21^(V)
The value of R1 plays a role in setting the dynamics of the
buck-boost voltage mode control loop. In general, a larger
value for R1 will increase stability but reduce the speed of
the transient response. A good starting point is to choose
R1 equal to 1MΩ and calculate the value of R2 needed to set
the target output voltage. If a large output capacitor is used,
the bandwidth of the converter is reduced and R1 may be
reduced to improve transient response. If a large inductor
or small output capacitor is used then a larger R1 should
be used to bring the loop toward more stable operation.
Table 8. Inductors for Step-Down Switching Regulator 1
MANUFACTURERS
PART NUMBER
VALUE
(μH) DCR (Ω)
Coilcraft
XPL4020-102ML
XPL4020-152ML
XPL4020-222ML
LPS6225-222ML
LPS6225-332ML
LPS6225-472ML
1.0
0.029
1.5
0.036
2.2
0.060
2.2
0.045
3.3
0.055
4.7
0.065
Cooper
SD14-1R2-R
SD14-1R5-R
SD14-2R0-R
SD25-2R2-R
1.2
0.034
1.5
0.039
2.0
0.045
2.2
0.031
Sumida
CDRH5D16NP-3R3N
3.3
0.045
TDK
VLF5014ST-1R0N2R7
1.0
0.050
VLF5014st-2R2N2R3
2.2
0.073
VLCF5020T-2R2N2R6-1 2.2
0.071
TOKO
1124BS-1R2N
1124BS-1R8N
1.2
0.047
1.8
0.056
Tokin
H-DI-0520-2R2
H-DI-0630-2R4
H-DI-0630-3R8
2.2
0.048
2.4
0.028
3.8
0.040
Wurth
744042001
744052002
744053003
7440530047
7440430022
1.0
0.028
2.5
0.030
3.0
0.024
4.7
0.030
2.2
0.023
MAX DC
CURRENT (A)
4.00
3.60
2.60
3.90
3.50
3.00
3.35
2.91
2.56
2.80
2.60
2.7
2.3
2.6
2.9
2.7
2.6
2.5
2
2.60
2.4
2.8
2.4
2.5
SIZE (mm) W × L × H
4.2 × 4.2 × 2.0
4.2 × 4.2 × 2.0
4.2 × 4.2 × 2.0
6.0 × 6.0 × 2.0
6.0 × 6.0 × 2.0
6.0 × 6.0 × 2.0
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 2.5
5.6 × 5.6 × 1.8
4.8 × 4.6 × 1.4
4.8 × 4.6 × 1.4
5.0 × 5.0 × 2.0
4.5 × 4.7 × 1.8
4.5 × 4.7 × 1.8
5.3 × 5.3 × 2.0
6.3 × 6.3 × 3.0
6.3 × 6.3 × 3.0
4.8 × 4.8 × 1.8
5.8 × 5.8 × 1.8
5.8 × 5.8 × 2.8
5.8 × 5.8 × 2.8
4.8 × 4.8 × 2.8
3589fe
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