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AS1324-BTTT-12 参数 Datasheet PDF下载

AS1324-BTTT-12图片预览
型号: AS1324-BTTT-12
PDF下载: 下载PDF文件 查看货源
内容描述: 1.5MHz的, 600毫安, DC / DC降压型稳压器 [1.5MHz, 600mA, DC/DC Step-Down Regulator]
分类和应用: 稳压器
文件页数/大小: 20 页 / 910 K
品牌: AMSCO [ AMS(艾迈斯) ]
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AS1324  
Data Sheet - Application Information  
Figure 25. Single Li-Ion 1.8V/600mA Regulator for Low Output Ripple  
4.7µH  
VOUT  
1.8V  
600mA  
4
3
VIN  
2.7 to 4.2V  
VIN  
SW  
CIN  
10µF  
COUT  
22µF  
AS1324-  
18  
5
1
EN  
VOUT  
GND  
2
External Component Selection  
Inductor Selection  
For most applications the value of the external inductor should be in the range of 2.2 to 6.8µH as the inductor value  
has a direct effect on the ripple current. The selected inductor must be rated for its DC resistance and saturation cur-  
rent. The inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VIN or VOUT.  
In Equation (EQ 2) the maximum inductor current in PWM mode under static load conditions is calculated. The satura-  
tion current of the inductor should be rated higher than the maximum inductor current as calculated with Equation (EQ  
3). This is recommended because the inductor current will rise above the calculated value during heavy load tran-  
sients.  
VOUT  
--------------  
1 –  
(EQ 2)  
(EQ 3)  
VIN  
-----------------------  
×
ΔIL = VOUT  
L × f  
ΔIL  
-------  
+
ILMAX = IOUTMAX  
2
Where:  
f = Switching Frequency (1.5 MHz typical)  
L = Inductor Value  
ILmax = Maximum Inductor current  
ΔIL = Peak to Peak inductor ripple current  
The recommended starting point for setting ripple current is ΔIL = 240mA (40% of 600mA).  
The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current  
to prevent core saturation. Thus, a 720mA rated inductor should be sufficient for most applications (600mA + 120mA).  
A easy and fast approach is to select the inductor current rating fitting to the maximum switch current limit of the con-  
verter.  
Note: For highest efficiency, a low DC-resistance inductor is recommended.  
Accepting larger values of ripple current allows the use of low inductance values, but results in higher output voltage  
ripple, greater core losses, and lower output current capability.  
www.austriamicrosystems.com  
Revision 1.03  
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