欢迎访问ic37.com |
会员登录 免费注册
发布采购

AAT2505 参数 Datasheet PDF下载

AAT2505图片预览
型号: AAT2505
PDF下载: 下载PDF文件 查看货源
内容描述: 双通道,降压型转换器/线性稳压器 [Dual Channel, Step-Down Converter/Linear Regulator]
分类和应用: 转换器稳压器
文件页数/大小: 26 页 / 845 K
品牌: ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
 浏览型号AAT2505的Datasheet PDF文件第9页浏览型号AAT2505的Datasheet PDF文件第10页浏览型号AAT2505的Datasheet PDF文件第11页浏览型号AAT2505的Datasheet PDF文件第12页浏览型号AAT2505的Datasheet PDF文件第14页浏览型号AAT2505的Datasheet PDF文件第15页浏览型号AAT2505的Datasheet PDF文件第16页浏览型号AAT2505的Datasheet PDF文件第17页  
AAT2505  
Dual Channel, Step-Down  
Converter/Linear Regulator  
The regulator features an enable/disable function.  
This pin (ENLDO) is active high and is compatible  
with CMOS logic. To assure the LDO regulator will  
switch on, the ENLDO turn-on control level must be  
greater than 1.5V. The LDO regulator will go into the  
disable shutdown mode when the voltage on the EN  
pin falls below 0.6V. If the enable function is not  
needed in a specific application, it may be tied to VIN  
to keep the LDO regulator in a continuously on state.  
either the input power or the enable input is  
applied. When pulled low, the enable input forces  
the converter into a low-power, non-switching state  
with a bias current of less than 1µA. A startup time  
of 150µs is achieved across the operating range.  
Low Dropout Operation  
For conditions where the input voltage drops to the  
output voltage level, the converter duty cycle  
increases to 100%. As 100% duty cycle is  
approached, the minimum off-time initially forces  
the high side on-time to exceed the 1.4MHz clock  
cycle and reduce the effective switching frequency.  
Once the input drops below the level where the out-  
put can be regulated, the high side P-channel  
MOSFET is turned on continuously for 100% duty  
cycle. At 100% duty cycle, the output voltage tracks  
the input voltage minus the IR drop of the high side  
When the regulator is in shutdown mode, an inter-  
nal 20kΩ resistor is connected between OUT and  
GND. This is intended to discharge COUT when the  
LDO regulator is disabled. The internal 20kΩ resis-  
tor has no adverse impact on device turn-on time.  
Step-Down Converter  
The AAT2505 buck is a constant frequency peak  
current mode PWM converter with internal compen-  
sation. It is designed to operate with an input voltage  
range of 2.7V to 5.5V. The output voltage ranges  
from 0.6V to the input voltage for the internally fixed  
version (see Figure 1) , and up to 3.3V for the exter-  
nally adjustable version (see Figure 2). The 0.6V  
fixed model is also the adjustable version and is  
externally programmable with a resistive divider. The  
converter MOSFET power stage is sized for 600mA  
load capability with up to 96% efficiency. Light load  
efficiency exceeds 80% at a 500µA load.  
P-channel MOSFET RDS(ON)  
.
Low Supply  
The under-voltage lockout (UVLO) guarantees suf-  
ficient VIN bias and proper operation of all internal  
circuitry prior to activation.  
Fault Protection  
For overload conditions, the peak inductor current is  
limited. Thermal protection disables switching when  
the internal dissipation or ambient temperature  
becomes excessive. The junction over-temperature  
threshold is 140°C with 15°C of hysteresis.  
Soft Start  
The AAT2505 soft-start control prevents output  
voltage overshoot and limits inrush current when  
VIN  
C3  
VIN  
C3  
3
5
9
6
7
8
4
3
5
9
6
7
8
4
VP  
VCC  
EN  
10µF  
VP  
VCC  
EN  
10µF  
10  
2
10  
2
VLDO  
ENLDO  
OUT  
VOUTBUCK  
VLDO  
ENLDO  
OUT  
VOUTBUCK  
L1  
L1  
LX  
LX  
4.7µH  
VOUTLDO  
R1  
11  
12  
1
4.7µH  
VOUTLDO  
FB  
11  
12  
1
FB  
POK  
SGND  
PGND  
R3  
100kΩ  
POK  
SGND  
PGND  
C8  
GND  
R3  
100kΩ  
C1  
4.7µF  
C4  
4.7µF  
100pF  
GND  
C1  
4.7µF  
C4  
4.7µF  
U1  
AAT2505  
R2  
59k  
U1  
AAT2505  
Figure 1: AAT2505 Fixed Output.  
Figure 2: AAT2505 with Adjustable Step-Down  
Output and Enhanced Transient Response.  
2505.2006.06.1.1  
13