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MAX1636EAP 参数 Datasheet PDF下载

MAX1636EAP图片预览
型号: MAX1636EAP
PDF下载: 下载PDF文件 查看货源
内容描述: 低电压,高精度降压型控制器,用于便携式CPU电源 [Low-Voltage, Precision Step-Down Controller for Portable CPU Power]
分类和应用: 控制器便携式
文件页数/大小: 24 页 / 220 K
品牌: MAXIM [ MAXIM INTEGRATED PRODUCTS ]
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Lo w -Vo lt a g e , P re c is io n S t e p -Do w n  
Co n t ro lle r fo r P o rt a b le CP U P o w e r  
HIGH-CURRENT PATH  
V
CC  
MAX1636  
VL  
SENSE RESISTOR  
GND  
BST  
MAX136  
LX  
MAX1636  
Figure 7. Capacitor Placement  
Figure 6. Kelvin Connections for the Current-Sense Resistors  
connections, the bottom layer for quiet connections  
(REF, CC, GND), and the inner layers for an uninter-  
rupted ground plane. Use the following step-by-step  
guide:  
terminals, which ensures that the ICs analog ground is  
sensing at the supply’s output terminals without interfer-  
ence from IR drops and ground noise. Other high-cur-  
re nt p a ths s hould a ls o b e minimize d , b ut foc us ing  
primarily on short ground and current-sense connec-  
tions eliminates about 90% of all PC board layout prob-  
le ms (s e e the PC b oa rd la youts in the MAX1636  
evaluation kit manual for examples).  
1) Place the high-power components (C1, C2, Q1, Q2,  
D1, L1, and R1) first, with their grounds adjacent.  
Minimize current-sense resistor trace lengths and  
ensure accurate current sensing with Kelvin con-  
nections (Figure 6).  
2) Place the IC and signal components. Keep the main  
switching nodes (LX nodes) away from sensitive  
analog components (current-sense traces and REF  
capacitor). Place the IC and analog components on  
the op p os ite s id e of the b oa rd from the p owe r-  
switching node. Important: The IC must be no fur-  
ther than 10mm from the current-sense resistors.  
Keep the gate-drive traces (DH, DL, and BST) short-  
er than 20mm and route them away from CSH, CSL,  
and REF. Place ceramic bypass capacitors close to  
the IC. The bulk capacitors can be placed further  
Minimize ground trace lengths in the high-current  
paths.  
Minimize other trace lengths in the high-current  
paths.  
— Use >5mm-wide traces.  
CIN to hig h-s id e MOSFET d ra in: 10mm  
max length  
— Rectifier diode cathode to low side  
— MOSFET: 5mm max length  
away. If using VL to power V , minimize noise by  
CC  
placing a 0.1µF capacitor close to the V  
pin and  
CC  
— LX node (MOSFETs, rectifier cathode, induc-  
tor): 15mm max length  
placing the 4.7µF capacitor further away, but closer  
than the boost diode (Figure 7).  
Ideally, surface-mount power components are butted  
up to one another with their ground terminals almost  
touching. These high-current grounds are then con-  
ne c te d to e a c h othe r with a wid e , fille d zone of  
top-layer copper so they do not go through vias. The  
resulting top-layer subground plane is connected to the  
normal inner-layer ground plane at the output ground  
3) Us e a s ing le -p oint s ta r g round whe re the inp ut  
ground trace, power ground (subground plane), and  
normal ground plane meet at the supply's output  
ground terminal. Connect both IC ground pins and  
all IC bypass capacitors to the normal ground plane.  
___________________Ch ip In fo rm a t io n  
TRANSISTOR COUNT: 3472  
22 ______________________________________________________________________________________  
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