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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  
Short-Circuit Protection  
Applications Information  
The AAT1160 uses a cycle-by-cycle current limit to pro-  
tect itself and the load from an external fault condition.  
When the inductor current reaches the internally set  
6.0A current limit, the P-channel MOSFET switch turns  
off and the N-channel synchronous rectifier is turned on,  
limiting the inductor and the load current.  
Setting the Output Voltage  
Figure 1 shows the basic application circuit for the  
AAT1160 and output setting resistors. Resistors R3 and  
R6 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 R6 is  
5.9kΩ. Although a larger value will further reduce quies-  
cent current, 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 R6 set to either  
5.9kΩ for good noise immunity or 59kΩ for reduced no  
load input current.  
During an overload condition, when the output voltage  
drops below 25% of the regulation voltage (0.15V at  
FB), the AAT1160 switching frequency drops by a factor  
of 4. This gives the inductor current ample time to reset  
during the off time to prevent the inductor current from  
rising uncontrolled in a short-circuit condition.  
Thermal Protection  
The AAT1160 includes thermal protection that disables  
the regulator when the die temperature reaches 140ºC.  
It automatically restarts when the temperature decreas-  
es by 25ºC or more.  
L1  
EP2  
VOUT  
5V, 2A  
VIN 4.5V -13 .2V  
R4  
3.8μH  
LX  
3
4
1
2
LX  
LX  
FB  
EN  
IN  
C3, C4  
2x22μF  
C1  
R3  
10Ω  
5
7
C6  
22μF  
100pF  
43.2kΩ  
C2  
0.1μF  
IN  
9
AAT1160  
R6  
AIN  
10  
11  
C8  
1μF  
COMP  
Frequency Synchronization  
5.9kΩ  
6
13  
16  
AGND  
DGND  
R5  
50kΩ  
The AAT1160 operates at a fixed 800kHz switching fre-  
quency, or it can be synchronized to an external signal.  
Synchronize switching to an external signal between  
500kHz and 1.6MHz by driving SYNC with that signal. In  
this mode, the rising edge of the signal at SYNC turns on  
the P-channel switch. When changing switching frequen-  
cy, the external components CIN, COUT and L must be  
changed according to the component equations. The  
external clock duty cycle is limited to a 30% to 90%  
range.  
14  
8
DGND  
PGND  
SYNC  
LDO  
DGND  
EP1  
C7  
150pF  
C9  
1μF  
Figure 1: Typical Application Circuit.  
The adjustable feedback resistors, combined with an  
external feed forward capacitor (C1 in Figure 1), deliver  
enhanced transient response for extreme pulsed load  
applications. The addition of the feed forward capacitor  
typically requires a larger output capacitor C3/C4 for  
stability. Larger C3/C4 values reduce overshoot and  
undershoot during startup and load changes. However,  
do not exceed 470pF to maintain stable operation.  
PWM or Light Load Mode  
The device can be set to operate in forced Pulse Width  
Modulation (PWM) mode to filter or set the switching  
noise to a desired frequency by connecting the SYNC to  
a high logic level. Alternately, a combination PWM/LL  
(Light Load) mode for improved light load efficiency can  
be set by connecting the SYNC pin to GND or a low logic  
level. When connecting SYNC to an external clock sig-  
nal, the device is always in forced PWM mode.  
The external resistors set the output voltage according  
to the following equation:  
R3⎞  
R6⎠  
V
OUT = 0.6V 1 +  
or  
V
-1 · R6  
OUT  
R3 =  
V
REF  
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10  
1160.2007.11.1.1