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LT1513CR 参数 Datasheet PDF下载

LT1513CR图片预览
型号: LT1513CR
PDF下载: 下载PDF文件 查看货源
内容描述: SEPIC Constant-或可编程电流/恒定电压电池充电器 [SEPIC Constant- or Programmable-Current/ Constant-Voltage Battery Charger]
分类和应用: 稳压器开关式稳压器或控制器电源电路电池开关式控制器
文件页数/大小: 16 页 / 303 K
品牌: Linear [ Linear ]
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LT1513/LT1513-2  
U
W U U  
APPLICATIONS INFORMATION  
The suggested way to control unity loop frequency is to  
increase the filter time constant on the IFB pin (R4/C4 in  
Figures 1 and 7). The filter resistor cannot be arbitrarily  
increased because high values will affect charging current  
accuracy. Charging current will increase by 1% for each  
40increase in R4. There is no inherent limitation on the  
value of C4, but if this capacitor is ceramic, it should be an  
X7R type to maintain its value over temperature. X7R  
dielectric requires a larger footprint.  
For example, assume VIN(MAX) = 15V, R3 = 0.4(charging  
current set to 0.25A), R4 = 24, R5 = 330and VBAT = 8V,  
0.4(4)(15)(12)(0.0015)(330)  
C4 =  
= 1µF  
6.3(25000)(39)(15 + 8)  
ThevalueforC4couldbereducedtoamoremanageablesize  
by increasing R4 to 75and reducing R5 to 300, yielding  
0.47µF for C4. The 2% increase in charging current can be  
ignored or factored into the value for R3.  
The formula for calculating the minimum value for the filter  
capacitor C4 is:  
More Help  
(R3)(4)(V )(12)(1500µ)(R5)  
IN  
Linear Technology Field Application Engineers have a CAD  
spreadsheet program for detailed calculations of circuit  
operating conditions. In addition, our Applications Depart-  
ment is always ready to lend a helping hand. The LT1371  
data sheet may also be helpful. The LT1513 is identical  
except for the current amplifier circuitry.  
C4 =  
2π(f)(R4)(V + V  
)
IN  
BAT  
VIN = Highest input voltage  
1500µ= Transconductance of error amplifier  
(EA)f = Desired unity-gain frequency  
VBAT = Battery voltage  
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