欢迎访问ic37.com |
会员登录 免费注册
发布采购

AAT2512IWP-AA-T1 参数 Datasheet PDF下载

AAT2512IWP-AA-T1图片预览
型号: AAT2512IWP-AA-T1
PDF下载: 下载PDF文件 查看货源
内容描述: 双400毫安高频降压转换器 [Dual 400mA High Frequency Buck Converter]
分类和应用: 转换器稳压器开关式稳压器或控制器电源电路开关式控制器
文件页数/大小: 20 页 / 732 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
 浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第8页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第9页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第10页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第11页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第13页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第14页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第15页浏览型号AAT2512IWP-AA-T1的Datasheet PDF文件第16页  
AAT2512  
Dual 400mA High Frequency Buck Converter  
The output voltage droop due to a load transient is  
To limit the bias current required for the external  
feedback resistor string, the minimum suggested  
value for R2 and R4 is 59kΩ. Although a larger  
value will reduce the quiescent current, it will also  
increase the impedance of the feedback node,  
making it more sensitive to external noise and  
interference. Table 2 summarizes the resistor val-  
ues for various output voltages with R2 and R4 set  
to either 59kΩ for good noise immunity or 221kΩ  
for reduced no load input current.  
dominated by the capacitance of the ceramic out-  
put capacitor. During a step increase in load cur-  
rent the ceramic output capacitor alone supplies  
the load current until the loop responds. As the loop  
responds, the inductor current increases to match  
the load current demand. This typically takes two  
to three switching cycles and can be estimated by:  
3
·
VDROOP FS  
ΔILOAD  
COUT  
=
·
V
V
1.5V  
0.6V  
- 1 ·  
R1 =  
OUT -1  
·
R2 =  
59kΩ = 88.5kΩ  
REF  
Once the average inductor current increases to the  
DC load level, the output voltage recovers. The  
above equation establishes a limit on the minimum  
value for the output capacitor with respect to load  
transients.  
The adjustable version of the AAT2512 in combina-  
tion with an external feedforward capacitor (C4 and  
C5 of Figure 2) delivers enhanced transient  
response for extreme pulsed load applications. The  
addition of the feedforward capacitor typically  
requires a larger output capacitor (C1 and C2) for  
stability.  
The internal voltage loop compensation also limits  
the minimum output capacitor value to 4.7µF. This  
is due to its effect on the loop crossover frequency  
(bandwidth), phase margin, and gain margin.  
Increased output capacitance will reduce the  
crossover frequency with greater phase margin.  
R2, R4 = 59kΩ R2, R4 = 221kΩ  
VOUT (V)  
R1, R3 (kΩ)  
R1, R3  
The maximum output capacitor RMS ripple current  
is given by:  
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  
75K  
113K  
150K  
187K  
221K  
261K  
301K  
332K  
442K  
464K  
523K  
715K  
1.00M  
1
VOUT · (VIN(MAX) - VOUT)  
IRMS(MAX)  
=
·
L · F · VIN(MAX)  
2 · 3  
Dissipation due to the RMS current in the ceramic  
output capacitor ESR is typically minimal, resulting in  
less than a few degrees rise in hot spot temperature.  
124  
137  
187  
267  
Adjustable Output Resistor Selection  
For applications requiring an adjustable output volt-  
age, the 0.6V version can be programmed exter-  
nally. Resistors R1 through R4 of Figure 2 program  
the output to regulate at a voltage higher than 0.6V.  
Table 2: Adjustable Resistor Values  
For Use With 0.6V Version.  
12  
2512.2006.06.1.4