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参数资料
| 型号： | LTC1731CMS8-8.2 |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | BATTERY CHARGE CONTROLLER, PDSO8 |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 5/8页 |
| 文件大小： | 99K |
| 代理商： | LTC1731CMS8-8.2 |
5
LTC1731
LINEAR TECHNOLOGY CONFIDENTIAL
OPERATIO
U
The LTC1731 is a linear battery charger controller. The
charge current is programmed by the combination of a
program resistor (RPROG) from the PROG pin to ground
and a sense resistor (RSENSE) between the VCC and SENSE
pins. RPROG sets a program current through an internal
trimmed 800
resistor setting up a voltage drop from VCC
at the input to the current amplifier (CA). The current
amplifier servos the gate of the external P-channel MOSFET
to force the same voltage drop across RSENSE which sets
the charge current. When the potential at the BAT pin
approaches the preset float voltage, the voltage amplifier
(VA) will start sinking current which shrinks the voltage
drop across RSENSE, thus reducing the charge current.
Charging begins when the potential at VCC pin rises above
the UVLO level and a program resistor is connected from
the PROG pin to ground. At the beginning of the charge
cycle, if the battery voltage is below 2.457V per cell, the
charger goes into a trickle charge mode. The trickle charge
current is 10% of the full-scale current. If the cell voltage
stays low for one quarter of the total charge time, the
charge sequence will be terminated immediately.
The charger goes into the fast charge constant-current
mode after the voltage on the BAT pin rises above 2.457V
per cell. In constant-current mode, the charge current is
set by the combination of RSENSE and RPROG.
When the battery approaches the final float voltage, the
charge current will begin to decrease. When the current
drops to 10% of the full-scale charge current, an internal
comparator will turn off the pull-down N-channel MOSFET
at the CHRG pin and connect a weak current source to
ground to indicate an end-of-charge (C/10) condition.
An external capacitor on the TIMER pin sets the total
charging time. After a time-out occurs, the charging will be
terminated immediately and the CHRG pin is forced to a
high impedance state. To restart the charge cycle, simply
remove the input voltage and reapply it, or float the PROG
pin momentarily.
For batteries like lithium-ion that require accurate final
float potential, the internal 2.457V reference, voltage am-
plifier and the resistor divider provide regulation with
±1%
(max) accuracy. For NiMH and NiCd batteries, the LTC1731
can be turned into a current source by pulling the TIMER
pin to VCC. When in the constant-current-only mode, the
voltage amplifier, timer and the trickle charge function are
all disabled.
When the input voltage is not present, the charger goes
into a sleep mode, dropping ICC to 5A. This greatly
reduces the current drain on the battery and increases the
standby time. The charger can be shut down by floating the
PROG pin. An internal current source will pull it high and
clamp at 3.5V.
APPLICATIONS INFORMATION
WU
U
Charge Termination
The charger is off when any of the following conditions
exist: the voltage at the VCC pin is below 4.1V, the voltage
at the VCC pin is higher than 4.1V but is less than 54mV
above VBAT, or the PROG pin is floating. The DRV pin will
be pulled to VCC and the internal resistor divider is discon-
nected 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 VCC
rises above 4.1V. To prevent oscillation around
VCC = 4.1V, 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 low (below 2.457V per cell) the charger goes
into trickle mode. The charge current is dropped to 10% of
the full-scale current. If the low cell voltage persists for one
quarter of the total charging time, the battery is considered
defective, the charging will be terminated and the CHRG
pin output is forced to a high impedance state.
Shutdown
The LTC1731 can be forced into shutdown by floating the
PROG pin and letting the internal 2.5
Acurrentsourcepull
the pin above the 2.457V shutdown threshold voltage. The
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相关代理商/技术参数 |
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| LTC1731EMS8-4.1 | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP 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 |
| LTC1731EMS8-4.1#PBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 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 |
| LTC1731EMS8-4.1#TR | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP 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 |
| LTC1731EMS8-4.1#TRPBF | 功能描述:IC CTRLR BATT CHRGR LI-ION 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 |
| LTC1731EMS8-4.2 | 功能描述:IC CTRLR BATT CHRGR LI-ION 8MSOP 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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