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