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参数资料
| 型号： | LTC4078EDD-2#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/16页 |
| 文件大小： | 0K |
| 描述： | IC USB POWER MANAGER 10-DFN |
| 标准包装： | 2,500 |
| 功能： | 电源管理 |
| 电池化学： | 锂离子（Li-Ion）、锂聚合物（Li-Pol） |
| 电源电压： | 4.3 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 供应商设备封装： | 10-DFN（3x3） |
| 包装： | 带卷 (TR) |
LTC4078/LTC4078X
APPLICATIONS INFORMATION
120 ° C – T A
Assumingθ JA is40°C/W(seeThermalConsiderations),the
ambient temperature at which the LTC4078/LTC4078X will
begin to reduce the charge current is approximately:
T A = 120°C – (5V – 3.3V) ? (800mA) ? 40°C/W
T A = 120°C – 1.36W ? 40°C/W = 120°C – 54.4°C
T A = 65.6°C
The LTC4078/LTC4078X can be used above 70.6°C ambi-
ent, but the charge current will be reduced from 800mA.
The approximate current at a given ambient temperature
can be approximated by:
I BAT =
(V IN – V BAT) ? JA
Using the previous example with an ambient temperature
of 75°C, the charge current will be reduced to approxi-
mately:
LTC4078/LTC4078X can deliver over 800mA to a battery
from a 5V supply at room temperature. Without a good
backside thermal connection, this number would drop to
much less than 500mA.
Input Capacitor Selection
When an input supply is connected to a portable product,
the inductance of the cable and the high-Q ceramic input
capacitor form an L-C resonant circuit. While the LTC4078/
LTC4078X are capable of withstanding input voltages as
high as 22V, if the input cable does not have adequate
mutual coupling or if there is not much impedance in
the cable, it is possible for the voltage at the input of the
product to reach as high as 2x the input voltage before it
settles out. To prevent excessive voltage from damaging
the LTC4078/LTC4078X during a hot insertion, it is best to
have a low voltage coef?cient capacitor at the input pins
to the LTC4078/LTC4078X. This is achievable by select-
I BAT =
120°C–75°C
(5V – 3.3V) ? 40 ° C / W
I BAT = 662mA
=
45 ° C
68 ° C / A
ing an X5R or X7R ceramic capacitor that has a higher
voltage rating than that required for the application. For
example, if the maximum expected input voltage is 15V,
a 25V X5R 1μF capacitor would be a better choice than
It is important to remember that LTC4078/LTC4078X
applications do not need to be designed for worst-case
thermal conditions, since the IC will automatically reduce
power dissipation when the junction temperature reaches
approximately 120°C.
Thermal Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on
the backside of the LTC4078/LTC4078X DFN package is
the smaller 16V X5R capacitor. Note that no charging will
occur with 15V in.
Using a tantalum capacitor or an aluminum electrolytic
capacitor for input bypassing, or paralleling with a ceramic
capacitor will also reduce voltage overshoot during a hot
insertion. Ceramic capacitors with Y5V or Z5U dielectrics
are not recommeded.
Alternatively, the following soft connect circuit can be
employed (as shown in Figure 4).
properly soldered to the PC board ground. When cor-
rectly soldered to a 2500mm 2 double sided 1oz copper
board, the LTC4078/LTC4078X has a thermal resistance
of approximately 40°C/W. Failure to make thermal contact
between the exposed pad on the backside of the package
+15V
INPUT INPUT CABLE
C2
100nF
R1
40k
C1
1 μ F
MN1
DCIN/USBIN
LTC4078
GND
and the copper board will result in thermal resistances far
greater than 40°C/W. As an example, a correctly soldered
Figure 4. Input Soft Connect Circuit
4078X F04
4078xfb
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4078X | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input Li-Ion Battery Charger with Overvoltage Protection |
| LTC4078XEDD#PBF | 功能描述:IC USB POWER MANAGER 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:61 系列:- 功能:电源管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:4.35 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:22-WFDFN 裸露焊盘 供应商设备封装:22-DFN（6x3）裸露焊盘 包装:管件 |
| LTC4078XEDD#TRPBF | 功能描述:IC USB POWER MANAGER 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:61 系列:- 功能:电源管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:4.35 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:22-WFDFN 裸露焊盘 供应商设备封装:22-DFN（6x3）裸露焊盘 包装:管件 |
| LTC4078XEDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input Li-Ion Battery Charger with Overvoltage Protection |
| LTC4078XEDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Input Li-Ion Battery Charger with Overvoltage Protection |
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