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AAT1160 参数 Datasheet PDF下载

AAT1160图片预览
型号: AAT1160
PDF下载: 下载PDF文件 查看货源
内容描述: 12V , 3A降压型DC / DC转换器 [12V, 3A Step-Down DC/DC Converter]
分类和应用: 转换器
文件页数/大小: 17 页 / 656 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
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PRODUCT DATASHEET  
AAT1160  
SwitchRegTM  
12V, 3A Step-Down DC/DC Converter  
Table 1 shows the resistor selection for different output  
voltage settings.  
mum recommended inductor is 3.8μH. For 3.3V and  
below, use a 2 to 2.2μH inductor. For optimum voltage-  
positioning load transients, choose an inductor with DC  
series resistance in the 15mto 20mrange. For  
higher efficiency at heavy loads (above 1A), or minimal  
load regulation (but some transient overshoot), the  
resistance should be kept below 18m. 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 (3A + 526mA). Table 2 lists  
some typical surface mount inductors that meet target  
applications for the AAT1160.  
R6 = 5.9kΩ  
R3 (kΩ)  
R6 = 59kΩ  
R3 (kΩ)  
VOUT (V)  
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  
5.0  
1.96  
2.94  
3.92  
4.99  
5.90  
6.81  
7.87  
8.87  
11.8  
12.4  
13.7  
18.7  
26.7  
43.2  
19.6  
29.4  
39.2  
49.9  
59.0  
68.1  
78.7  
88.7  
118  
124  
137  
187  
267  
Manufacturer’s specifications list both the inductor DC  
current rating, which is a thermal limitation, and the  
peak current rating, which is determined by the satura-  
tion characteristics. The inductor should not show any  
appreciable saturation under normal load conditions.  
Some inductors may meet the peak and average current  
ratings yet result in excessive losses due to a high DCR.  
Always consider the losses associated with the DCR and  
its effect on the total converter efficiency when selecting  
an inductor. For example, the 3.7H CDR7D43 series  
inductor selected from Sumida has an 18.9mΩ DCR and  
a 4.3ADC current rating. At full load, the inductor DC  
loss is 170mW which gives only a 1.13% loss in effi-  
ciency for a 3A, 5V output.  
432  
Table 1: Resistor Selection for Different Output  
Voltage Settings. Standard 1% Resistors are  
Substituted for Calculated Values.  
Inductor Selection  
For most designs, the AAT1160 operates with inductors  
of 2μH 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:  
Input Capacitor Selection  
The input capacitor reduces the surge current drawn  
from the input and switching noise from the device. The  
input capacitor impedance at the switching frequency  
shall be less than the input source impedance to prevent  
high frequency switching current passing to the input. A  
low ESR input capacitor sized for maximum RMS current  
must be used. Ceramic capacitors with X5R or X7R  
dielectrics are highly recommended because of their low  
ESR and small temperature coefficients. A 22μF ceramic  
capacitor is sufficient for most applications.  
VOUT · (VIN  
-
VOUT  
)
L1 =  
VIN · ΔIL · FOSC  
Where IL 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 32% of the maximum load current 3A, or  
IL = 959mA. For output voltages above 3.3V, the mini-  
Max DCR  
(mΩ)  
Rated DC  
Current (A)  
Size WxLxH  
(mm)  
Manufacturer  
Part Number  
L (μH)  
Sumida  
Sumida  
Coilcraft  
CDRH103RNP-2R2N  
CDR7D43MNNP-3R7NC  
MSS1038-382NL  
2.2  
3.7  
3.8  
16.9  
18.9  
13  
5.10  
4.3  
4.25  
10.3x10.5x3.1  
7.6x7.6x4.5  
10.2x7.7x3.8  
Table 2: Typical Surface Mount Inductors.  
w w w . a n a l o g i c t e c h . c o m  
1160.2007.11.1.1  
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