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AT1312B 参数 Datasheet PDF下载

AT1312B图片预览
型号: AT1312B
PDF下载: 下载PDF文件 查看货源
内容描述: 高效率,恒定电流白光LED的驱动器 [High Efficiency, Constant Current White-LEDs Driver]
分类和应用: 驱动器
文件页数/大小: 16 页 / 402 K
品牌: AIMTRON [ AIMTRON TECHNOLOGY ]
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AT1312A/B/C  
Preliminary Product Information  
High Efficiency, Constant Current  
White-LEDs Driver  
Application Information  
External components of boost converter can be designed by performing simple  
calculations.  
Boost inductor  
Inductor selection depends on input voltage, output voltage, maximum output current,  
switching frequency and availability of inductor values. The following boost circuit  
equations are useful in choosing the inductor values based on the application. They  
allow the trading of peak current and inductor value while allowing for consideration  
of component availability and cost.  
The peak inductor current is given by:  
IL  
2
ILpeak = ILAVG  
+
IO  
ILAVG  
=
1D  
where:  
IL is the inductor peak-to-peak current ripple and is decided by:  
Vin  
L
D
fOSC  
IL =  
×
D is the MOSFET turn on ratio and is decided by:  
VO V in  
D =  
VO  
fOSC is the switching frequency.  
The inductor should be chosen to be able to handle this current and inductor saturation  
current rating should be greater than IPEAK  
.
Diode selection  
The output diode has average current of IO, and peak current the same as the  
inductor’s peak current and a voltage rating at least 1.5 times the output voltage.  
Schottky diode is recommended and it should be able to handle those current.  
Output Capacitor  
The AT1312 series are specially compensated to be stable with capacitors which have  
a worst- case minimum value of 1uF at the particular VOUT being set. Output ripple  
voltage requirements also determine the minimum value and type of capacitors.  
Output ripple voltage consists of two components the voltage drop caused by the  
switching current through the ESR of the output capacitor and the charging and  
discharging of the output capacitor:  
VO Vin  
IO  
VRIPPLE = ILPEAK × ESR +  
×
VO  
COUT × fOSC  
For low ESR ceramic capacitors, the output ripple is dominated by the charging or  
discharging of the output capacitor.  
7F, No.9,PARK AVENUE. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C.  
Tel: 886-3-563-0878  
2/23/2006 REV:1.1  
Fax: 886-3-563-0879  
WWW: http://www.aimtron.com.tw  
Email: service@aimtron.com.tw  
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