Buffering Scheme Drives Large
abstract: this application notes shows how to buffer the triplex backplane drive outputs of a lcd driver such as max7231 family to increase the capacitive drive capability. this enables a large lcd to be driven without ghosting and other artifacts due to backplane waveform distortion.
to conserve pins, many lcd drivers triplex their drive signals—a technique that enables ac waveforms on trhree common lines and three segment lines to activate any standard character of a seven-segment display. large lcds of 1 or more exhibit a large capacitance between the common and segment electrodes (several nonofarads), which presents a problem for standard lcd drivers.
these drivers' high output impedance (50kω, for example) causes difficulty in driving capacitance, and the consequent ac-waveform distortioncan produce ghosting and shadow segments in the display. the drive circuit in figure 1 solves this problem by introducing a buffer amplifier for each of the three common lines. each amplifier may be programmed independently for a quiescent current of 10, 100 or 1000µa. in this application, the bias network applies a voltage that sets the three quiescent currents to 100µa.
the display driver and triple op amp operate between 5v and ground, and the com signals range from 5v to ~ 1v. to assure that these signals remain within the amplifiers' common-mode range. we attenuate the signalsby one half and operate the buffers at a gain of two. the circuit drives eight 1 displays and is suitable for ambient temperature variations of 15°f or less. at the highest expected temperature, you should adjust r1 so that no off segments are visible.
figure 1. three buffer amplifiers enable this standard lcd driver (ic1) to control eight large (1) seven-segment displays.
我国将重点研发支撑低碳冬奥的智能电网综合示范工程项目
六类网线水晶头和五类网线水晶头通用吗
大联大友尚集团推出基于Actions与Vesper产品的TWS骨传导蓝牙耳机方案
开关电源的直流变换器电路图详解
威士丹利打造智能芯片模组荣获Zigbee 3.0技术认证
Buffering Scheme Drives Large
导电膏的作用_导电膏成分_电接触导电膏的使用方法
神仙代码静态测试工具 Helix QAC 2022.3中的新增功能
5v1a充电器芯片方产品特性以及它的优势的介绍
三星初代旗舰GT-i9000居然能运行安卓7.0？
DigiPCBA常见问题之关于可靠性
国产FPGA最新动态：CME-M7芯片初放光芒
创维50H7 50英寸超薄全面屏4K超高清智能网络电视浅析
智能路由器哪个好用
电网谐波对用电造成的危害
最新黑科技 不用半导体将电路导电率提升 10 倍
通用汽车2023年盈利101亿美元，2024年拟减成本20亿美元
如何设计出分离式电源
用热敏电阻打造廉价LED恒流源解决方案
全球AI挑战赛”年度总决赛在京收官
to conserve pins, many lcd drivers triplex their drive signals—a technique that enables ac waveforms on trhree common lines and three segment lines to activate any standard character of a seven-segment display. large lcds of 1 or more exhibit a large capacitance between the common and segment electrodes (several nonofarads), which presents a problem for standard lcd drivers.
these drivers' high output impedance (50kω, for example) causes difficulty in driving capacitance, and the consequent ac-waveform distortioncan produce ghosting and shadow segments in the display. the drive circuit in figure 1 solves this problem by introducing a buffer amplifier for each of the three common lines. each amplifier may be programmed independently for a quiescent current of 10, 100 or 1000µa. in this application, the bias network applies a voltage that sets the three quiescent currents to 100µa.
the display driver and triple op amp operate between 5v and ground, and the com signals range from 5v to ~ 1v. to assure that these signals remain within the amplifiers' common-mode range. we attenuate the signalsby one half and operate the buffers at a gain of two. the circuit drives eight 1 displays and is suitable for ambient temperature variations of 15°f or less. at the highest expected temperature, you should adjust r1 so that no off segments are visible.
figure 1. three buffer amplifiers enable this standard lcd driver (ic1) to control eight large (1) seven-segment displays.
我国将重点研发支撑低碳冬奥的智能电网综合示范工程项目
六类网线水晶头和五类网线水晶头通用吗
大联大友尚集团推出基于Actions与Vesper产品的TWS骨传导蓝牙耳机方案
开关电源的直流变换器电路图详解
威士丹利打造智能芯片模组荣获Zigbee 3.0技术认证
Buffering Scheme Drives Large
导电膏的作用_导电膏成分_电接触导电膏的使用方法
神仙代码静态测试工具 Helix QAC 2022.3中的新增功能
5v1a充电器芯片方产品特性以及它的优势的介绍
三星初代旗舰GT-i9000居然能运行安卓7.0？
DigiPCBA常见问题之关于可靠性
国产FPGA最新动态：CME-M7芯片初放光芒
创维50H7 50英寸超薄全面屏4K超高清智能网络电视浅析
智能路由器哪个好用
电网谐波对用电造成的危害
最新黑科技 不用半导体将电路导电率提升 10 倍
通用汽车2023年盈利101亿美元，2024年拟减成本20亿美元
如何设计出分离式电源
用热敏电阻打造廉价LED恒流源解决方案
全球AI挑战赛”年度总决赛在京收官