高灰度等级高压背光驱动电源电路的分析和研究

论文总字数：35024字

摘 要

在手机等移动设备非常流行的当代，背光的精确控制对于使用者的用户体验非常重要，其中关键主要是WLED的驱动电路的设计。

本课题是研究高灰度等级高压背光驱动电源电路，针对企业已经设计好的整个集成芯片中大电路的部分子电路进行分析研究。芯片输入电压主要为锂电池电压2.7V5.5V，其中集成了30V大电流开关(1.2A限)；具有高效性：转换效率高达90%； 为了保证双路调光的精确性，采用双电流阱设计，每串电流可达25 mA，同时保证了2%典型电流匹配与精度；调光方式采用PWM与单线数字调光两种方式；boost开关管的开关频率为0.8MHz。

本文首先介绍了国内外WLED驱动的研究现状和趋势，然后分析了LED的驱动原理和方式。主要的子电路的电路仿真分析包括带隙基准源电路的温度特性，误差放大器的幅频特性，电流沉的电路分析和输出电流源的匹配，振荡器工作原理分析，调光电路如何在PWM和单线调光两种方式下实现高灰度等级调光的分析。

关键词：WLED驱动，电流阱，调光电路

ABSTRACT

In the contemporary era where mobile devices such as mobile phones are very popular, precise control of the backlight is very important to the user's user experience, and the key is the design of the drive circuit of the WLED.

This subject is to study the high gray level high voltage backlight driving power supply circuit, and analyzes and studies some sub-circuits of the large circuit in the integrated chip that the enterprise has designed. The chip input voltage is mainly lithium battery voltage 2.7V ~ 5.5V, which integrates 30V high-current switch (1.2A limit); with high efficiency: conversion efficiency of up to 90%; in order to ensure the accuracy of dual-channel dimming, using dual current Well design, each string current up to 25 mA, while ensuring 2% typical current matching and accuracy; dimming using PWM and single-wire digital dimming; boost switch tube switching frequency of 0.8MHz.

This article first introduced the research status and trends of WLED driver at home and abroad, and then analyzed the driving principle and method of LED. The main subcircuit simulations include the temperature characteristics of the bandgap reference circuit, the amplitude-frequency characteristics of the error amplifier, the circuit analysis of the current sink and the matching of the output current source, the analysis of the operating principle of the oscillator, how the dimming circuit is in the PWM and High-gloss dimming analysis is achieved in both single-wire dimming modes.

KEYWORDS： WLED driving circuit，current sink，dimming circui

目录

摘要................................................................ I

Abstract.............................................................II

1. 绪论........................ ..............................1
   1. 课题研究的背景和意义..................................... 1
   2. 研究现状和发展方向....................................... 2
   3. 本论文主要内容和安排.....................................9传到过-pm定失调情况，我们使用蒙特卡罗仿真，其仿真结果如下 3
2. LED驱动电路原理分析...................................... 4

2.1 LED工作原理............................................. 4

2.2 常见LED驱动器种类...................................... 6

2.2.1 电荷泵...............................................6

2.2.2 线性稳压源驱动.......................................7

2.2.3 开关电源驱动......................................... 8

2.3 Boost转换器基本结构.................................... . 9

2.4 Boost转换器的工作模式................................... 11

2.4.1 连续导通模式.......................................11

2.4.2 非连续导通模式.....................................11

2.5 Boost转换器的调制方式................................... 12

2.5.1 PWM.................................................12

2.5.2 PFM.................................................13

2.5.3 PSM.................................................13

2.6 环路控制方式............................................ 14

2.6.1 电压模式控制........................................14

2.6.2 电流模式控制........................................15

2.7 本章小结................................................ 16

1. 驱动电路系统分析与设计....................................17

3.1 芯片设计参数............................................. 17

3.2 设计方案考虑............................................ .17

3.3 系统电路框图和芯片引脚介绍............................... 19

3.3.1 系统电路框图.......................................19

3.3.2 芯片引脚介绍.......................................20

3.4 本章小结................................................. 21

第四章 电路设计与仿真............................................22

4.1 带隙电压基准源设计与仿真分析............................. 23

4.1.1 带隙电压基准源的设计...............................23

4.1.2 带隙电压基准源的仿真分析...........................26

4.2 振荡器设计与仿真分析............... ......................27

4.2.1 振荡器电路的设计...................................27

4.2.2 振荡器电路的仿真分析...............................28

4.3 运算放大器设计与仿真分析................................. 29

4.1.1 运算放大器的设计...................................29

4.1.2 运算放大器的仿真分析...............................32

4.4 电流阱电路设计与仿真分析................................. 33

4.5 调光电路的设计与仿真分析............ .....................36

4.5.1 单线数字调光.......................................36

4.5.2 PWM调光控制........................................36

4.6 本章小结............................ .....................37

第五章 总结......................................................38

致谢...............................................................39

参考文献...........................................................40

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