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| 型号： | LTC4081EDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/24页 |
| 文件大小： | 0K |
| 描述： | IC USB POWER MANAGER 10-DFN |
| 标准包装： | 121 |
| 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： | 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-WFDFN 裸露焊盘 |
| 供应商设备封装： | 10-DFN（3x3） |
| 包装： | 管件 |
| 产品目录页面： | 1341 (CN2011-ZH PDF) |
LTC4081
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
Using the previous example with an ambient temperature
of 85°C, the charge current will be reduced to approxi-
=
ef?ciency at that particular load.
It is not necessary to perform worst-case power dissipa-
tion scenarios because the LTC4081 will automatically
mately:
I BAT =
115 ° C ? 85 ° C 30 ° C
( 6 V ? 3 V ) ? 43 ° C / W 129 ° C / A
= 2 3 2 . 6 mA
115 ° C ? T A
( V CC ? V BAT ) ? θ JA
reducethechargecurrenttomaintainthedietemperature
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 LTC4081 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 LTC4081 will begin to reduce the 250mA
charge current is approximately:
T A = 115°C – (6V – 3V) ? (250mA) ? 43°C/W
T A = 115°C – 0.75W ? 43°C/W = 115°C – 32.25°C
T A = 82.75°C
If there is more power dissipation due to the regulator,
the thermal regulation will begin at a somewhat lower
temperature. In the above circumstances, the LTC4081
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:
I BAT =
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in the
Programming Charge Current section.
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.
Thermistors
The LTC4081 NTC trip points are designed to work with therm-
istors whose resistance-temperature characteristics follow
Vishay Dale’s “R-T Curve 1.” The Vishay NTHS0603NO1N1002J
is an example of such a thermistor. However, Vishay Dale
has many thermistor products that follow the “R-T Curve 1”
characteristic in a variety of sizes. Furthermore, any thermis-
tor whose ratio of R COLD to R HOT is about 5 will also work
(Vishay Dale R-T Curve 1 shows a ratio of R COLD to R HOT of
3.266/0.5325 = 6.13).
4081f
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4081EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:500mA Li-Ion Charger with NTC Input and 300mA Synchronous Buck |
| LTC4085 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Efficiency Battery Charger/USB Power Manager |
| LTC4085-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:USB Power Manager with Ideal Diode Controller and 4.1V Li-Ion Charger |
| LTC4085-3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:USB Power Manager with Ideal Diode Controller and 3.95V Li-Ion Charger |
| LTC4085EDE | 制造商:Linear Technology 功能描述:USB Power Manager 14-Pin DFN EP |
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