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SY8089 参数 Datasheet PDF下载

SY8089图片预览
型号: SY8089
PDF下载: 下载PDF文件 查看货源
内容描述: []
分类和应用:
文件页数/大小: 11 页 / 3058 K
品牌: SILICONIMAGE [ Silicon image ]
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SY8089/8089A  
of inductance can be slightly off the calculation value  
without significantly impacting the performance.  
2) The saturation current rating of the inductor must  
be selected to be greater than the peak inductor  
current under full load conditions.  
Layout Design:  
The layout design of SY8089 regulator is relatively  
simple. For the best efficiency and minimum noise  
problems, we should place the following components  
close to the IC: CIN, L, R1 and R2.  
1) It is desirable to maximize the PCB copper area  
connecting to GND pin to achieve the best tmal and  
noise performance. If the board space allowed, a  
ground plane is highly desirable.  
2) CIN must be close to Pins IN and GND. The loop  
area formed by CIN and GND must be minimized.  
V
OUT(1-VOUT/VIN  
,
MAX  
)
ISAT  
,
MIN > IOUT  
,
MAX  
+
2 FSW  
L
3) The DCR of the inductor and the core loss at the  
switching frequency must be low enough to  
achieve the desired efficiency requirement. It is  
desirable to choose an inductor with DCR<50mΩ  
to achieve a good overall efficiency.  
3) The PCB copper aressociated with LX pin must  
be minimized to avoid thtential noise problem.  
Enable Operation  
4) The components R1, R2, and the trace connecting to  
the FB pin must NOT be adjacent to the LX net on the  
PCB layout to avoid the noise problem.  
Pulling the EN pin low (<0.4V) will shut down the  
device. During shut down mode, the SY8089 shutdown  
current drops to lower than 0.1uA. Driving the EN pin  
high (>1.5V) will turn on the IC again.  
5) If the system chip interfacing with the EN pin has a  
hh impedance state at shutdown mode and the IN pin  
is nected directly to a power source such as a LiIon  
battery, it is desirable to add a pull down 1Mresistor  
between the EN and GND pins to prevent the noise  
from falsely turning on the regulator at shutdown mode.  
Load Transient Considerations:  
The SY8089 regulator IC integrates the compensation  
components to achieve good stability and fast transient  
responses. In some applications, adding a 22pF ceramic  
cap in parallel with R1 may further speed up the load  
transient responses and is thus recommended for  
applications with large load transient step requirements.  
AN_SY8089/A Rev. 0.9  
Silergy Corp. Confidential- Prepared for Customer Use Only 9  
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