Linear LTC4012 4A电池充电控制方案

Linear公司的LTC 4012-3是恒流/恒压电池充电控制器,采用同步准恒定频率PWM控制架构,不会产生和陶瓷电容有关的可听见噪音.充电电流由外接电阻设定,并由可编程电阻上的输出电压值来监视.可编程电流精度在4%,输出浮动电压精度在±0.5%,输入电压从6V到28V, 输出电压从2V到28V.主要用在笔记本电脑,手提仪器和电池备用系统.本文介绍了LTC 4012-3主要特性,方框图,典型应用电路,性能测试电路以及12.6V 4A充电器电路图.

The LTC 4012-3 is a constant-current/constant-voltage battery charger controller. It uses a synchronous quasiconstant frequency PWM control architecture that will not generate audible noise with ceramic bulk capacitors. Charge current is set by external resistors and can be monitored as an output voltage across the programming resistor.

With no built-in termination, the LTC4012-3 charges a wide range of batteries under external control. The LTC4012-3 features fully adjustable output voltage. For charge management and safety, the IC includes an input P-channel MOSFET ideal diode controller, battery (output) overvoltage protection, reverse charge current protection, PWM soft-start and robust non-overlap control for an all N-channel MOSFET PWM power stage.

The device includes AC adapter input current limiting, which maximizes the charge rate for a fi xed input power level. An external sense resistor programs the input current limit,and the ICL status pin indicates reduced charge current as a result of AC adapter current limiting. Ideal diode control at the adaptor input improves charger effi ciency.

The CHRG status pin is active during all charging modes, including special indication for low charge current.

LTC 4012-3主要特性:

General Purpose Battery Charger Controller

Efficient 550kHz Synchronous Buck PWM Topology

±0.5% Output Float Voltage Accuracy

Programmable Charge Current: 4% Accuracy

Programmable AC Adapter Current Limit: 3% Accuracy

No Audible Noise with Ceramic Capacitors

INFET Low Loss Ideal Diode PowerPath Control

Wide Input Voltage Range: 6V to 28V

Wide Output Voltage Range: 2V to 28V

Indicator Outputs for Charging, C/10 Current Detection and Input Current Limiting

Analog Charge Current Monitor

Micropower Shutdown

20-Pin 4mmx4mmx0.75mm QFN Package

应用:

Notebook Computers

Portable Instruments

Battery Backup Systems



图1.LTC 4012-3方框图



图2.LTC 4012-3典型应用



图3.LTC 4012-3测试电路图



图4.采用LTC 4012-3的12.6V 4A充电器电路图