A white led driver circuit is presented in this paper . the circuit drives up to four white leds with regulated constant current for uniform intensity . by utilizing proprietary adaptive 1x / 1 . 5x modes and ultra - low - dropout current regulators , it maintains the highest possible efficiency over the full 1 - cell li + battery input voltage range 整体电路以恒定电流驱动4只白光led ,利用1倍/ 1 . 5倍分数型电荷泵和低压差电流调节器,在整个锂电池供电电压范围内保持最高的效率,并使四个白光led获得均匀的亮度。
After which , the battery will be charged by large constant current to allow the fast charging . finally , the constant voltage charging is adopted to guarantee the battery was charged to its full capacity . under the condition that the temperature has raised to a certain threshold at the constant current charging stage , the over temperature circuit is performing and it provides a compensation current which switches the system to constant temperature charging mode with the intention of protecting the ic 即在充电初期采用较小的电流对电池进行预处理,对出现过放电的电池进行修复和保护;然后采用较大的恒定电流对电池充电,实现快速充电的目的;最后采用恒定压充电,确保电池充满;在恒流充电阶段,当芯片温度上升到一定程度时,芯片过热保护电路开始工作,该电路以提供充电补偿电流的形式使充电进入恒温充电模式,对芯片进行保护。
The trickle charging uses small current at the initial of charging cycle to fix and protect the over - discharged battery ; after which , the battery will be charged by large constant current to allow the fast charging ; finally , the constant voltage charging is adopted to guarantee that the battery is charged to its full capacity 在充电初期采用较小的电流对电池进行预处理,对出现过放电的电池进行修复和保护;然后采用较大的恒定电流对电池充电,实现快速充电的目的;最后采用恒压充电,确保电池充满。
Tddb evaluation experiments are carried out with constant current stress on mos capacitors with ultra - thin gate oxides , and a method of precise measurement and characterization of the trap density and accumulative failure is presented . this method is based on dynamic equilibrium equation of charge trapping 采用恒定电流应力对超薄栅氧化层mos电容进行了tddb评价实验，提出了精确测量和表征陷阱密度超薄栅氧化层经时击穿效应与可靠性仿真技术研究和累积失效率的方法。
The research shows that students misunderstand the relation between force and motion . gravity and action / reaction ; that in dc circuit , students of different age groups have the belief of " consumption of current " , " clashing currents " and " the battery as a constant current generator " ; that in understanding the concepts of electricity students lack th e knowledge of relating the micro with the macro ; and that students have serious difficulties in understanding the propagation of mechanics wave , the speed of wave and superposition , and do not make a distinction between the initial conditions and the medium properties of the system 具体表现在：学生对力和运动的关系、重力和平衡、作用力与反作用力存在一些误解；对直流电路，不同年龄的学生不同程度地存在电流消耗、碰撞电流、恒定电流源等观念，而且对电学概念的理解缺乏宏观与微观的联系；学生在机械波的传播、波速、波的叠加上存在严重的困难，对于机械波的传播学生不能区分初始条件和媒质特性，并错误地将动力学某些观念与机械波进行类比。
The converter was designed to drive up to a 5 white leds with a constant current when the device operates with pulse width modulation ( pwm ) and to power an organic led display with a constant voltage when the circuit operates in pulse frequency modulation ( pfm ) for higher efficiency 它采用1 . 5微米bicmos / dmos工艺,输入电压范围是2 . 7 5 . 5v ,电路以恒定电流驱动5个串连白光led或者以恒定电压驱动一个oled显示器。在输出恒定电压时采用pfm调制方式;输出恒流时则采用pwm调制方式。
