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参数资料
| 型号： | LTC4068EDD-4.2#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER BATT LI-ON 8-DFN |
| 标准包装： | 121 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion） |
| 电源电压： | 4.25 V ~ 6.5 V |
| 工作温度： | -40°C ~ 85°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-EP（3x3） |
| 包装： | 管件 |
| 产品目录页面： | 1341 (CN2011-ZH PDF) |
LTC4068-4.2/LTC4068X-4.2
APPLICATIO S I FOR ATIO
charged condition and eliminates the need for periodic
charge cycle initiations. The CHRG output enters a pull-
down state during recharge cycles.
If the battery is removed from the charger, a sawtooth
waveform of approximately 100mV appears at the charger
filter can be used on the PROG pin to measure the average
battery current, as shown in Figure 2. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
output. This is caused by the repeated cycling between
termination and recharge events. This cycling results in
pulsing at the CHRG output; an LED connected to this pin
will exhibit a blinking pattern, indicating to the user that a
LTC4068-4.2
PROG
GND
10k
R PROG
C FILTER
CHARGE
CURRENT
MONITOR
CIRCUITRY
2 π ? 10 5 ? C PROG
battery is not present. The frequency of the sawtooth is
dependent on the amount of output capacitance.
Stability Considerations
The constant-voltage mode feedback loop is stable with-
out an output capacitor, provided a battery is connected to
the charger output. With no battery present, an output
capacitor on the BAT pin is recommended to reduce ripple
voltage. When using high value, low ESR ceramic capaci-
tors, it is recommended to add a 1 ? resistor in series with
the capacitor. No series resistor is needed if tantalum
capacitors are used.
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. The constant-current mode stability
is affected by the impedance at the PROG pin. With no
additional capacitance on the PROG pin, the charger is
stable with program resistor values as high as 20k; how-
ever, additional capacitance on this node reduces the
maximum allowed program resistor. The pole frequency
at the PROG pin should be kept above 100kHz. Therefore,
if the PROG pin is loaded with a capacitance, C PROG , the
following equation can be used to calculate the maximum
resistance value for R PROG :
1
R PROG ≤
Average, rather than instantaneous charge current may be
of interest to the user. For example, if a switching power
supply operating in low current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
406842 F02
Figure 2. Isolating Capacitive Load on PROG Pin and Filtering
Power Dissipation
It is not necessary to design for worst-case power dissi-
pation scenarios because the LTC4068 automatically
reduces the charge current during high power conditions.
The conditions that cause the LTC4068 to reduce charge
current through thermal feedback can be approximated
by considering the power dissipated in the IC. Nearly all
of this power dissipation is generated by the internal
MOSFET—this is calculated to be approximately:
P D = (V CC – V BAT ) ? I BAT
where P D is the power dissipated, V CC is the input supply
voltage, V BAT is the battery voltage and I BAT is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
T A = 120 ° C – P D θ JA
T A = 120 ° C – (V CC – V BAT ) ? I BAT ? θ JA
Example: An LTC4068 operating from a 5V supply is
programmed to supply 800mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.3V. Assuming
θ JA is 50 ° C/W (see Thermal Considerations), the ambient
temperature at which the LTC4068 will begin to reduce the
charge current is approximately:
T A = 120 ° C – (5V – 3.3V) ? (800mA) ? 50 ° C/W
T A = 120 ° C – 1.36W ? 50 ° C/W = 120 ° C – 68 ° C
T A = 52 ° C
instantaneous current pulses. In such a case, a simple RC
406842fa
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| LTC4068XEDD-4.2 | 功能描述:IC CHARGER BATT LI-ON 8-DFN RoHS:否 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 |
| LTC4068XEDD-4.2#PBF | 功能描述:IC CHARGER BATT LI-ON 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
| LTC4068XEDD-4.2#TR | 功能描述:IC CHARGER BATT LI-ON 8-DFN RoHS:否 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 |
| LTC4068XEDD-4.2#TRPBF | 功能描述:IC CHARGER BATT LI-ON 8-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 |
| LTC4069 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Standalone 750mA Li-Ion Battery Charger in 2 × 2 DFN with NTC Thermistor Input |
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