AS1324 查看數據表（PDF） - austriamicrosystems AG
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AS1324 Datasheet PDF : 21 Pages
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AS1324
Datasheet - Application Information
Table 5. Recommended Inductors
Part Number
L
LQH32CN2R2M33
2.2µH
LQH32CN4R7M33
4.7µH
LPS3008-222MLC
2.2µH
LPS3015-222MLC
2.2µH
MOS6020-222MLC
2.2µH
MOS6020-472MLC
4.7µH
CDRH3D16NP-2R2N
2.2µH
CDRH3D16ND-4R7N
4.7µH
DCR
97mΩ
150mΩ
175mΩ
110mΩ
35mΩ
50mΩ
72mΩ
105mΩ
Current Rating
790mA
650mA
1100mA
2000mA
3260mA
1820mA
1200mA
900mA
Dimensions (L/W/T)
3.2x2.5x2.0mm
3.2x2.5x2.0mm
3.1x3.1x0.8mm
3.1x3.1x1.5mm
6.0x6.8x2.4mm
6.0x6.8x2.4mm
4.0x4.0x1.8mm
4.0x4.0x1.8mm
Manufacturer
Murata
www.murata.com
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
Figure 26. Efficiency Comparison of Different Inductors, VIN = 2.7V, VOUT = 1.8V and 1.2V
95
VOUT = 1.8V
95
VOUT = 1.2V
90
90
85
85
80
80
75
70
1
LQH3 2 CN2 R2
LPS3015-222
LQH3 2 CN4 R7
LPS3 0 0 8 - 2 2 2
M OS6020-222
M OS6020-472
10
100
Output Current (mA)
1000
75
70
1
LQH3 2 CN2 R2
LPS3015-222
LQH3 2 CN4 R7
LPS3 0 0 8 - 2 2 2
M OS6020-222
M OS6020-472
10
100
Output Current (mA)
1000
9.3 Output Capacitor Selection
The advanced fast-response voltage mode control scheme of the AS1324 allows the use of tiny ceramic capacitors. Because of their lowest
output voltage ripple low ESR ceramic capacitors are recommended. X7R or X5R dielectric output capacitor are recommended.
At high load currents, the device operates in PWM mode and the RMS ripple current is calculated as:
1 – V-----O----U---T--
IRMSCOUT
=
VOUT
×
-------------V----I--N----
L×f
×
-------1---------
2× 3
(EQ 4)
While operating in PWM mode the overall output voltage ripple is the sum of the voltage spike caused by the output capacitor ESR plus the
voltage ripple caused by charging and discharging the output capacitor:
∆VOUT
=
VO
U
T
×
-1----–-----V------V---O-----I---U-N------T---
L×f
×
---------------1-----------------
8 × COUT × f
+
E
S
R
(EQ 5)
Higher value, low cost ceramic capacitors are available in very small case sizes, and their high ripple current, high voltage rating, and low ESR
make them ideal for switching regulator applications. Because the AS1324 control loop is not dependant on the output capacitor ESR for stable
operation, ceramic capacitors can be used to achieve very low output ripple and accommodate small circuit size.
At light loads, the converter operates in powersave mode and the output voltage ripple is in direct relation to the output capacitor and inductor
value used. Larger output capacitor and inductor values minimize the voltage ripple in powersave mode and tighten DC output accuracy in
powersave mode.
www.ams.com/DC-DC_Step-Up/AS1324
Revision 1.06
12 - 21
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