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参数资料
| 型号： | LTC1731EMS8-8.2 |
| 厂商： | Linear Technology |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC BATT CHRG CNTRLR LI-ION 8MSOP |
| 标准包装： | 50 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子，镍镉，镍氢 |
| 电源电压： | 8.8 V ~ 12 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-MSOP |
| 包装： | 管件 |
| 产品目录页面： | 1340 (CN2011-ZH PDF) |
| 其它名称： | LTC1731EMS88.2 |
LTC1731-8.2/LTC1731-8.4
APPLICATIO N S I N FOR M ATIO N
Charger Conditions
The charger is off when any of the following conditions
exist: the V CC pin is less than 8.2V, the droput voltage (V CC
- V BAT ) is less than 54mV, the PROG pin is floating, or the
timer has ended. The DRV pin will be pulled to V CC and the
internal resistor divider is disconnected to reduce the
current drain on the battery.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input
voltage and keeps the charger in shutdown mode until V CC
rises above 8.2V. To prevent oscillation around
V CC = 8.2V, the UVLO circuit has built-in hysteresis.
Trickle Charge and Defective Battery Detection
At the beginning of the charging sequence, if the battery
voltage is less than 4.95V the charger goes into trickle
charge mode. The charge current is reduced to 10% of the
full-scale current. If the low battery voltage persists for
one quarter of the total charging time, the battery is
considered defective, charging will be terminated and the
CHRG pin output is forced to a high impedance state.
Shutdown
The LTC1731-8.2/LTC1731-8.4 can be forced into shut-
down by floating the PROG pin and allowing the internal
2.5 μ A current source to pull the pin above the 2.457V
shutdown threshold voltage. The DRV pin is then pulled
up to V CC turning off the external P-channel MOSFET. The
For best stability over temperature and time, 1% resistors
are recommended. The closest 1% resistor value is 19.6k.
Programming the Timer
The programmable timer is used to terminate the charge.
The length of the timer is programmed by an external
capacitor at the TIMER pin. The total charge time is:
Time (Hours) = (3 Hours)(C TIMER /0.1 μ F)
The timer starts when the input voltage greater than 8.2V
is applied and the program resistor is connected to ground.
After a time-out occurs, the CHRG output will become high
impedance indicating that the charge cycle has ended.
Connecting the TIMER pin to V CC disables the timer and
also puts the charger into a constant-current mode. To
only disable the timer function, short the TIMER pin to
GND.
CHRG Status Output Pin
When the charge cycle starts, the CHRG pin is pulled to
ground by an internal N-channel MOSFET that can drive an
LED. When the charge current drops to 10% of the full-
scale current ( C /10), the N-channel MOSFET turns off and
a weak 100 μ A current source to ground is connected to the
CHRG pin. After a time-out occurs, the CHRG pin goes
high impedance indicating that the charge cycle has ended.
By using two different value pull-up resistors, a micropro-
cessor can detect three states from this pin (charging,
C /10 and stop charging). See Figure 1.
internal timer is reset in the shutdown mode.
V +
V DD
Programming Charge Current
The formula for the battery charge current (see Block
Diagram) is:
7
V CC
LTC1731-8.4
CHRG
2
100k
2k
μ PROCESSOR
OUT
I BAT = (2.457V/R PROG )(800 ? /R SENSE )
IN
1731 F01
where R PROG is the total resistance from the PROG pin to
ground.
Figure 1. Microprocessor Interface
For example, if 0.5A charge current is needed, select a
value for R SENSE that will drop 100mV at the maximum
charge current. R SENSE = 0.1V/0.5A = 0.2 ? , then calculate:
R PROG = (2.457V/500mA)(800 ? /0.2 ? ) = 19.656k
sn1731 17318fs
8
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| LTC1731ES8-4.1 | 功能描述:IC CTRLR BATT CHRGR LI-ION 8SOIC 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 |
| LTC1731ES8-4.1#PBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 8SOIC 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 |
| LTC1731ES8-4.1#TR | 功能描述:IC CTRLR BATT CHRGR LI-ION 8SOIC 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 |
| LTC1731ES8-4.1#TRPBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:1 系列:- 功能:充电管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:3.75 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:剪切带 (CT) 产品目录页面:669 (CN2011-ZH PDF) 其它名称:MCP73831T-2ACI/OTCT |
| LTC1731ES8-4.2 | 功能描述:IC CTRLR BATT CHRGR LI-ION 8SOIC 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 |
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