Datasheet

LTC3589/LTC3589-1/
LTC3589-2
24
3589ff
For more information www.linear.com/3589
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+
R1
R2






(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 ()
MAX DC
CURRENT (A) SIZE (mm) W × L × H
Coilcraft XPL4020-102ML
XPL4020-152ML
XPL4020-222ML
LPS6225-222ML
LPS6225-332ML
LPS6225-472ML
1.0
1.5
2.2
2.2
3.3
4.7
0.029
0.036
0.060
0.045
0.055
0.065
4.00
3.60
2.60
3.90
3.50
3.00
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
Cooper SD14-1R2-R
SD14-1R5-R
SD14-2R0-R
SD25-2R2-R
1.2
1.5
2.0
2.2
0.034
0.039
0.045
0.031
3.35
2.91
2.56
2.80
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 1.45
5.2 × 5.2 × 2.5
Sumida CDRH5D16NP-3R3N 3.3 0.045 2.60
5.6 × 5.6 × 1.8
TDK VLF5014ST-1R0N2R7
VLF5014st-2R2N2R3
VLCF5020T-2R2N2R6-1
1.0
2.2
2.2
0.050
0.073
0.071
2.7
2.3
2.6
4.8 × 4.6 × 1.4
4.8 × 4.6 × 1.4
5.0 × 5.0 × 2.0
TOKO 1124BS-1R2N
1124BS-1R8N
1.2
1.8
0.047
0.056
2.9
2.7
4.5 × 4.7 × 1.8
4.5 × 4.7 × 1.8
Tokin H-DI-0520-2R2
H-DI-0630-2R4
H-DI-0630-3R8
2.2
2.4
3.8
0.048
0.028
0.040
2.6
2.5
2
5.3 × 5.3 × 2.0
6.3 × 6.3 × 3.0
6.3 × 6.3 × 3.0
Wurth 744042001
744052002
744053003
7440530047
7440430022
1.0
2.5
3.0
4.7
2.2
0.028
0.030
0.024
0.030
0.023
2.60
2.4
2.8
2.4
2.5
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