AS1325 Datasheet, PDF (13/17 Pages) ams AG – 300mA Step-Up DC-DC Converter

AS1325
Data Sheet - Application Information
9 Application Information
Inductor Selection
The control circuitry of the AS1325 permits a wide range of inductor values to be selected – from 4.7 to 22µH; The sys-
tem is optimized for 10µH.
The intended application should dictate the value of L. The trade-off between required PCB surface area and desired
output ripple are the determining factors: smaller values for L require less PCB space, larger values of L reduce output
ripple. If the value of L is large enough to prevent IMAX from being reached before tON expires, the AS1325 output
power will be reduced.
Note: Coils should be able to handle 500mARMS and have a ISAT ≥ 1A and should have a RIND ≤ 100mΩ.
Table 5. Recommended Inductors
Part Number
MOS6020-103ML
MOS6020-472ML
MOS6020-332ML
CDRH4D18-100
CDRH4D18-6R8
CR43-6R8
CDRH4D18-4R7
SD0403-6R8M
SD0403-4R7M
L
10µH
4.7µH
3.3µH
10µH
6.8µH
6.8µH
4.7µH
6.8µH
4.7µH
DCR
93mΩ
50mΩ
46mΩ
200mΩ
200mΩ
131.2mΩ
162mΩ
132mΩ
109mΩ
Current Rating Dimensions (L/W/T)
Manufacturer
1A
1.5A
6.8x6.0x2.4mm
6.8x6.0x2.4mm
Coilcraft
www.coilcraft.com
1.8A
6.8x6.0x2.4mm
0.61A
0.76A
6.9x5.0x2.0mm
6.9x5.0x2.0mm
Sumida
www.sumida.com
0.95A
4.8x4.3x3.5mm
0.84A
6.9x5.0x2.0mm
0.95A
1.15A
4.9x4.5x3.2mm
4.9x4.5x3.2mm
ACT
www.act1.com
Figure 29. Efficiency Comparison of Different Inductors;
VIN = 2.5V, VOUT = 3.3V
94
90
86
82
78
74
70
66
62
10uH Coi l cr af t (M OS6020-103M L)
10uH Sumi da (CDRH4D18-100)
6. 8uH Sumi da (CR43-6R8)
6. 8uH A CT (SD0403-6R8M -02)
4. 7uH Coi l cr af t (M OS6020-472M L)
4. 7uH Sumi da (CDRH4D18-4R7)
4. 7uH A CT (SD0403-4R7M -02)
3. 3uH Coi l cr af t (M OS6020-332M L)
58
0.1
1
10
100
Output Current (mA)
1000
Figure 30. Efficiency Comparison of Different Inductors;
VIN = 3.0V, VOUT = 3.3V
96
94
92
90
88
86
84
82
80
78
76
74
72
70
68
0.1
10uH Coi l c r af t (M OS6020-103M L)
10uH Sumi da (CDRH4D18-100)
6. 8uH Sumi da (CR43-6R8)
6. 8uH A CT (SD0403-6R8M -02)
4. 7uH Coi l cr af t (M OS6020-472M L)
4. 7uH Sumi da (CDRH4D18-4R7)
4. 7uH A CT (SD0403-4R7M -02)
3. 3uH Coi l cr af t (M OS6020-332M L)
1
10
100
Output Current (mA)
1000
www.austriamicrosystems.com
Revision 1.01
13 - 17