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AS1301A-BTDT 参数 Datasheet PDF下载

AS1301A-BTDT图片预览
型号: AS1301A-BTDT
PDF下载: 下载PDF文件 查看货源
内容描述: 5V / 50毫安低噪音无电感升压转换器 [5V/50mA Low Noise Inductorless Boost Converter]
分类和应用: 转换器升压转换器
文件页数/大小: 16 页 / 1060 K
品牌: AMSCO [ AMS(艾迈斯) ]
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AS1301  
Data Sheet - Application Information  
9 Application Information  
External Component Selection  
The high internal oscillator frequency of 1MHz permits the use of small capacitors for both the flying capacitors and the  
output capacitors. For any given load value of the flying- and output capacitors as well as their ESR are affecting the  
output voltage performance.  
In general, the capacitor’s ESR is inversely proportional to its physical size. Larger capacitances and higher voltage  
ratings tend to reduce ESR. The ESR is a function of the frequency too, so it must be rated at the devices operating  
frequency. Another factor affecting capacitor ESR is temperature.  
Note: Many capacitors have a huge capacity variation over temperature. This can be compensated by choosing a  
capacitor with a better thermal coefficient or by choosing a larger nominal value to ensure proper operation  
over temperature.  
Input and Output Capacitor Selection  
It is not critical which type of input bypass capacitor CBAT and output filter capacitor COUT is used, but it will still affect  
the performance of the charge-pump. Low ESR capacitors should be used to minimize VOUT ripple. Multi-layer ceramic  
capacitors are recommended since they have extremely low ESR and are available in small footprints.  
Input Capacitor  
An 1.2µF/2.2µF input bypass low ESR capacitor such as tantalum or ceramic is recommended to reduce noise and  
supply transients. During startup and mode change it supplies part of the peak input current drawn by the device.  
Table 4. Recommended Input Capacitor  
Part Number  
C
TC Code Rated Voltage Dimensions (L/W/T)  
X7R 10V 2x1.2x1.35mm  
Manufacturer  
Murata  
www.murata.com  
GRM21BR71A225KA01  
2.2µF  
Output Capacitor  
The output capacitor is charged to the VOUT voltage during pumping phase. The ESR of the output capacitor intro-  
duces steps in the output voltage waveform whenever the charge pump charges COUT. These steps contribute to the  
ripple voltage of VOUT. Therefore, ceramic or tantalum low ESR capacitors are recommended for COUT to minimize  
the output voltage ripple.  
Table 5. Recommended Output Capacitor  
Part Number  
C
TC Code Rated Voltage Dimensions (L/W/T)  
X7R 10V 2x1.2x1.35mm  
Manufacturer  
Murata  
www.murata.com  
GRM21BR71A225KA01  
2.2µF  
Charge-Pump Capacitor Selection  
To ensure the required output current and avoid high peak currents the values of the flying capacitors CFLY1 and CFLY2  
are very critical. A 120nF capacitor is sufficient for most applications. Dependent on the operation mode the AS1301  
alternately charges and discharges the CFLY1/2 . While the ESR of the output capacitor produces part of the output  
voltage ripple, the voltage drop caused by the ESR of the flying capacitors affects the maximum available output  
voltage. Therefore low ESR capacitors, e.g. tantalum or ceramic, are recommended for the flying capacitors as well.  
Table 6. Recommended Charge-Pump Capacitor  
Part Number  
C
TC Code Rated Voltage Dimensions (L/W/T)  
Manufacturer  
Murata  
www.murata.com  
GRM188R71E224KA88  
220nF  
X7R  
25V  
1.6x0.8x0.87mm  
www.austriamicrosystems.com  
Revision 1.00  
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