参数资料
| 型号： | LTC4080EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/20页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER LI-ION 10-MSOP |
| 标准包装： | 2,500 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion） |
| 电源电压： | 3.75 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-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 供应商设备封装： | 10-MSOP 裸露焊盘 |
| 包装： | 带卷 (TR) |
LTC4080
APPLICATIO S I FOR ATIO
Where V OUT is the regulated output of the switching
regulator, I OUT is the regulator load and η is the regulator
ef?ciency at that particular load.
It is not necessary to perform worst-case power dissipa-
tion scenarios because the LTC4080 will automatically
reduce the charge current to maintain the die temperature
at approximately 115°C. However, the approximate ambi-
ent temperature at which the thermal feedback begins to
protect the IC is:
T A = 115°C – P D θ JA
T A = 115°C – (V CC – V BAT ) ? I BAT ? θ JA if the regulator
is off.
Example: Consider the extreme case when an LTC4080 is
operating from a 6V supply providing 250mA to a 3V Li-Ion
battery and the regulator is off. The ambient temperature
above which the LTC4080 will begin to reduce the 250mA
charge current is approximately:
T A = 115°C – (6V – 3V) ? (250mA) ? 43°C/W
V CC Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-layer
ceramic capacitors. Because of the self-resonant and high
Q characteristics of some types of ceramic capacitors, high
voltage transients can be generated under some start-up con-
ditions, such as connecting the battery charger input to a live
power source. Adding a 1 Ω series resistor in series with an
X5R ceramic capacitor will minimize start-up voltage transients.
For more information, refer to Application Note 88.
SWITCHING REGULATOR
Setting the Buck Converter Output Voltage
The LTC4080 regulator compares the FB pin voltage with
an internal 0.8V reference to generate an error signal at the
output of the error ampli?er. A voltage divider from V OUT
to ground (as shown in the Block Diagram) programs the
output voltage via FB using the formula:
V OUT = 0 . 8 V ? ? 1 +
T A = 115°C – 0.75W ? 43°C/W = 115°C – 32.25°C
T A = 82.75°C
?
?
R7 ?
R 8 ? ?
If there is more power dissipation due to the regulator,
the thermal regulation will kick in at a somewhat lower
temperature than this. In the above circumstances, the
LTC4080 can be used above 82.75°C, but the charge current
will be reduced from 250mA. The approximate current at
a given ambient temperature can be calculated:
Keeping the current low (<5μA) in these resistors maxi-
mizes ef?ciency, but making them too low may allow stray
capacitance to cause noise problems and reduce the phase
margin of the error amp loop. To improve the frequency
response, a phase-lead capacitor (C PL ) of approximately
10pF can be used. Great care should be taken to route the
I BAT =
115 ° C ? T A
( V CC ? V BAT ) ? θ JA
FB line away from noise sources, such as the inductor or
the SW line.
I BAT =
=
= 2 3 2 . 6 mA
? ? 1 ? OUT ?
Δ I L =
Usingthepreviousexamplewithanambienttemperature
of 85°C, the charge current will be reduced to approxi-
mately:
115 ° C ? 85 ° C 30 ° C
( 6 V ? 3 V ) ? 43 ° C / W 129 ° C / A
Note: 1V = 1J/C = 1W/A
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in
the Programming Charge Current section.
Inductor Selection
The value of the inductor primarily determines the cur-
rent ripple in the inductor. The inductor ripple
current Δ I L decreases with higher inductance and
increases with higher V IN or V OUT :
V OUT ? V ?
f 0 ? L ? V IN ?
Accepting larger values of Δ I L allows the use of low
inductances, but results in higher output voltage ripple,
greater core losses, and lower output current capability. A
4080fb
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4080X | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck in 3mm × 3mm DFN |
| LTC4080XEDD#PBF | 功能描述:IC CHARGER LI-ION 10-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 |
| LTC4080XEDD#TRPBF | 功能描述:IC CHARGER LI-ION 10-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 |
| LTC4080XEDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck in 3mm × 3mm DFN |
| LTC4080XEDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck in 3mm × 3mm DFN |
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