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| 型号： | LTC4070IDDB#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC BATT CHRGR LIION/POLY 8DFN |
| 产品培训模块： | LTC4070 - Li-Ion/Polymer Shunt Battery Charger System |
| 标准包装： | 500 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion）、锂聚合物（Li-Pol） |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 供应商设备封装： | 8-DFN（3x2） |
| 包装： | 带卷 (TR) |
LTC4070
APPLICATIONS INFORMATION
The voltage at the NTC pin depends on the ratio of the NTC
thermistor value, R NTC , and a bias resistor, R NOM . Choose
R NOM equal to the value of the thermistor at 25°C. R NOM
is 10k for a Vishay NTHS0402N02N1002F thermistor with
a B 25/85 value of 3490. R NOM must be connected from
NTCBIAS to NTC. The ratio of the NTC pin voltage to the
NTCBIAS voltage is:
R NTC
( R NTC + R NOM )
When the thermistor temperature rises, the resistance
drops; and the resistor divider between R NOM and the
thermistor lowers the voltage at the NTC pin.
An NTC thermistor with higher B 25/85 values may also
be used with the LTC4070. However the temperature trip
points are shifted due to the higher negative temperature
coefficient of the thermistor. To correct for this difference
add a resistor, R FIX , in series with the higher B 25/85 value
thermistor to shift the ratio,
R FIX + R NTC
( R FIX + R NTC + R NOM )
up to the internal resistive divider tap points: NTC TH1
through NTC TH4 . For a 100k thermistor with a B 25/85 value
of 3950 NTHS0402N01N1003F, at 70°C (with R NOM =
100k) choose R FIX = 3.92k?. The temperature trip points
are found by looking up the thermistor R/T values plus
R FIX that correspond to the ratios for NTC TH1 = 36.5%,
NTC TH2 = 29.0%, NTC TH3 = 22.8%, and NTC TH4 = 17.8%.
Selecting R FIX = 3.92k results in trip points of 39.9°C,
49.4°C, 59.2°C and 69.6°C.
Another technique may be used without adding an
additional component. Instead decrease R NOM to adjust
the NTC TH thresholds for a given R/T thermistor profile. For
example, if R NOM = 88.7k (with the same 100k thermistor)
then the temperature trip points are 41.0°C, 49.8°C, 58.5°C,
and 67.3°C.
When using the NTC features of the LTC4070 it is important
to keep in mind that the maximum shunt current increases
as the float voltage, V FLOAT_EFF drops with NTC conditioning.
Reviewing the Typical Application with a 12V wall adapter
in Figure 1; the input resistor, R IN , should be increased
to 165Ω such that the maximum shunt current does not
exceed 50mA at the lowest possible float voltage due to
NTC conditioning, V FLOAT_MIN = 3.8V.
Thermal Considerations
At maximum shunt current, the LTC4070 may dissipate up
to 205mW. The thermal dissipation of the package should
be taken into account when operating at maximum shunt
current so as not to exceed the absolute maximum junc-
tion temperature of the device. With q JA of 40°C/W, in the
MSOP package, at maximum shunt current of 50mA the
junction temperature rise is about 8°C above ambient.
With q JA of 76°C/W in the DFN package, at maximum
shunt current of 50mA the junction temperature rise is
about 16°C above ambient.
Operation with an External PFET to Boost Shunt Current
Table 2 lists recommended devices to increase the
maximum shunt current. Due to the requirement for low
capacitance on the DRV pin node, it is recommended that
only low gate charge and high threshold PFET devices be
used. Also it is recommended that careful PCB layout be
used to keep leakage at the DRV pin to a minimum as the
I DRV(SINK) current is typically 3μA.
Refer to device manufacturers data sheets for maximum
continuous power dissipation and thermal resistance when
selecting an external PFET for a particular application.
Table 2. Recommended External Shunt PFETS
DEVICE VENDOR Q GS V TH(MIN) R DS(ON)
FDN352AP Fairchild 0.50nC –0.8V 0.33
Si3467DV Vishay 1.7nC –1.0V 0.073
Si3469DV Vishay 3.8nC –1.0V 0.041
DMP2130LDM
DMP3015LSS
Diodes Inc.
Diodes Inc.
2.0nC
7.2nC
–0.6V
–1.0V
0.094
0.014
4070fc
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4070IDDBTRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Li-Ion/Polymer Shunt Battery Charger System |
| LTC4070IMS8E | 制造商:LINER 制造商全称:Linear Technology 功能描述:Li-Ion/Polymer Shunt Battery Charger System |
| LTC4070IMS8E#PBF | 功能描述:IC BATT CHRGR LIION/POLY 8MSOP 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 |
| LTC4070IMS8E#TRPBF | 功能描述:IC BATT CHRGR LIION/POLY 8MSOP 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 |
| LTC4070IMS8EPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Li-Ion/Polymer Shunt Battery Charger System |
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