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AAT1153 参数 Datasheet PDF下载

AAT1153图片预览
型号: AAT1153
PDF下载: 下载PDF文件 查看货源
内容描述: 2A降压转换器 [2A Step-Down Converter]
分类和应用: 转换器
文件页数/大小: 20 页 / 686 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
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PRODUCT DATASHEET  
AAT1153  
2A Step-Down Converter  
for stability. The external resistor sets the output voltage  
according to the following equation:  
Applications Information  
L1  
VOUT  
2.2μH  
VIN 2.5V-5.5V  
1.8V, 2A  
1
2
3
8
R1⎞  
LX  
LX  
FB  
EN  
IN  
V
OUT = 0.6V · 1 +  
7
5
C3  
22pF  
R2  
R1  
C1  
22μF  
C2  
634kΩ  
AAT1153-0.6  
22μF  
AIN  
V  
OUT - 1 · R2  
0.6V  
10  
9
6
R2  
316kΩ  
AGND  
AGND  
PGND  
PGND  
R1 =  
4
Table 1 shows the resistor selection for different output  
voltage settings.  
Figure 1: Basic Application Circuit for the  
Adjustable Output Version.  
R2 = 59kΩ  
R1 (kΩ)  
R2 = 316kΩ  
R1 (kΩ)  
VOUT (V)  
L1  
0.8  
0.9  
1.0  
1.1  
1.2  
1.3  
1.4  
1.5  
1.8  
1.85  
2.0  
2.5  
3.3  
19.6  
29.4  
39.2  
49.9  
59.0  
68.1  
78.7  
88.7  
118  
124  
137  
187  
267  
105  
158  
210  
261  
316  
365  
422  
475  
634  
655  
732  
1000  
1430  
VOUT  
2.2μH  
1.8V, 2A  
VIN 2.5V-5.5V  
1
2
3
8
LX  
LX  
EN  
IN  
7
5
C1  
22μF  
C2  
22μF  
AAT1153-1.8  
AIN  
OUT  
10  
9
6
4
AGND  
AGND  
PGND  
PGND  
Figure 2: Basic Application Circuit for the Fixed  
Output Versions.  
Setting the Output Voltage  
Figure 1 shows the basic application circuit with the  
AAT1153 adjustable output version while Figure 2 shows  
the application circuit with the AAT1153 fixed output ver-  
sion. For applications requiring an adjustable output  
voltage, the AAT1153-0.6 adjustable version can be  
externally programmed. Resistors R1 and R2 in Figure 1  
program the output to regulate at a voltage higher than  
0.6V. To limit the bias current required for the external  
feedback resistor string while maintaining good noise  
immunity, the minimum suggested value for R2 is 59kΩ.  
Although a larger value will further reduce quiescent cur-  
rent, it will also increase the impedance of the feedback  
node, making it more sensitive to external noise and  
interference. Table 1 summarizes the resistor values for  
various output voltages with R2 set to either 59kΩ for  
good noise immunity or 316kΩ for reduced no load input  
current.  
Table 1: Resistor Selections for Different Output  
Voltage Settings (Standard 1% Resistors  
Substituted For Calculated Values).  
Inductor Selection  
For most designs, the AAT1153 operates with inductor  
values of 1μH to 4.7μH. Low inductance values are  
physically smaller but require faster switching, which  
results in some efficiency loss. The inductor value can  
be derived from the following equation:  
VOUT · (VIN - VOUT  
)
L =  
VIN · ΔIL · fOSC  
Where ΔIL is inductor ripple current. Large value induc-  
tors lower ripple current and small value inductors result  
in high ripple currents. Choose inductor ripple current  
approximately 30% of the maximum load current 2A, or  
The adjustable version of the AAT1153, combined with  
an external feed forward capacitor (C3 in Figure 1),  
delivers enhanced transient response for extreme pulsed  
load applications. The addition of the feed forward  
capacitor typically requires a larger output capacitor C2  
ΔIL = 600mA  
w w w . a n a l o g i c t e c h . c o m  
1153.2007.11.1.1  
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