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AAT1106 参数 Datasheet PDF下载

AAT1106图片预览
型号: AAT1106
PDF下载: 下载PDF文件 查看货源
内容描述: 600mA降压转换器 [600mA Step-Down Converter]
分类和应用: 转换器
文件页数/大小: 18 页 / 1028 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
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AAT1106  
600mA Step-Down Converter  
Part  
L (µH)  
Max DCR (m)  
Rated DC Current (A)  
Size WxLxH (mm)  
1.4  
2.2  
3.3  
4.7  
1.0  
2.2  
3.3  
4.7  
1.5  
2.2  
3.3  
4.7  
56.2  
71.2  
86.2  
108.7  
4.5  
2.52  
1.75  
1.44  
1.15  
1,72  
1.32  
1.04  
0.84  
1.29  
1.14  
0.98  
0.79  
Sumida CR43  
4.5x4.0x3.5  
75  
110  
Sumida CDRH4D18  
Toko D312C  
4.7x4.7x2.0  
3.6x3.6x1.2  
162  
120  
140  
180  
240  
Table 2: Typical Surface Mount Inductors.  
For output voltages above 2.0V, when light-load  
efficiency is important, the minimum recommended  
inductor size is 2.2µH. For optimum voltage-posi-  
tioning load transients, choose an inductor with DC  
series resistance in the 50mto 150mrange.  
For higher efficiency at heavy loads (above  
200mA), or minimal load regulation (with some  
transient overshoot), the resistance should be kept  
below 100m. The DC current rating of the induc-  
tor should be at least equal to the maximum load  
current plus half the ripple current to prevent core  
saturation (600mA + 105mA). Table 2 lists some  
typical surface mount inductors that meet target  
applications for the AAT1106.  
Slope Compensation  
The AAT1106 step-down converter uses peak cur-  
rent mode control with a unique adaptive slope  
compensation scheme to maintain stability with  
lower value inductors for duty cycles greater than  
50%. Using lower value inductors provides better  
overall efficiency and also makes it easier to stan-  
dardize on one inductor for different required out-  
put voltage levels. In order to do this and keep the  
step-down converter stable when the duty cycle is  
greater than 50%, the AAT1106 separates the  
slope compensation into 2 phases. The required  
slope compensation is automatically detected by  
an internal circuit using the feedback voltage VFB  
before the error amp comparison to VREF  
.
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  
saturation 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 con-  
sider the losses associated with the DCR and its  
effect on the total converter efficiency when select-  
ing an inductor. For example, the 2.2ꢀH CR43  
series inductor selected from Sumida has a  
71.2mΩ DCR and a 1.75ADC current rating. At full  
load, the inductor DC loss is 25mW which gives a  
2.8% loss in efficiency for a 600mA, 1.5V output.  
VREF  
VFB  
Error Amp  
When below 50% duty cycle, the slope compensa-  
tion is 0.284A/µs; but when above 50% duty cycle,  
the slope compensation is set to 1.136A/µs. The  
output inductor value must be selected so the  
inductor current down slope meets the internal  
slope compensation requirements.  
12  
1106.2007.07.1.0