Abstract: You can configure a group of analog mulTIplexers as a large, mulTI-plane video mux that easily selects mulTI-channel video sources such as Y-C, R'G'B' and Y'PbPr.

The variety of video sources available to a home video-switching system has grown from a few composite inputs to many mulTI-signal sources. These include cable, HDTV, satellite STB, VCR, DVD, video games; in broadcast, and multi-PC or graphic KVM (PC) applications. Each requires an NxM:1 multiplexer, in which M is the number of sources and N is the number of channels that make up the signal. As an example, sixteen R', G', B' or Y, Pb, Pr sources require a 3x16:1 multiplexer. Constructing such a multiplexer is difficult, and programming the source selection requires that you combine the individual 16:1 MUX control with the three channels (Table 1).

You can configure a group of analog multiplexers as a large, multi-plane video mux that easily selects multi-channel video sources such as Y-C, R'G'B' and Y'PbPr. The 3x16:1 mux mentioned above is composed of six 8:1 multiplexers (Figure 1) controlled by a 4-bit binary code for source selection. (MAX4315 ICs include a 2V/V fixed-gain output buffer.) The only external circuitry required is half an SN7404 hex inverter for inverting the shutdown signals, and 75Ω source and load resistors for implementing unity gain when driving a back-terminated load. Substituting a MAX4312 (8-channel video mux with variable-gain output buffer) allows variable gain while rejecting input common-mode voltages.


Figure 1. This multi-plane multiplexer selects any one of 16 input signals, each of which consists of the three channels R, G, and B.

The wide bandwidth and high slew rate of these ICs make them ideal for selecting standard video and high-definition broadcast video, as well as graphic sources up to UXGA resolution and above, for KVM applications. No additional buffering is required, because the ICs can drive 150Ω back-terminated coax directly, to within < 0.75V of the supply rails using single or dual supplies. Their fast switching speed (40ns) and low glitch voltage (10mVP-P) allow, in addition to source selection, insertion of on-screen display (OSD), closed captioning, and tele-text in broadcast and graphics video.

Table 1. Source-Selection Programming

	A0	A1	A2	A3
RGB#1	>0 上一篇：Buffered Linear-Ramp Generator 下一篇：Inexpensive Peak Detector Feat 相关文章 海尔为何能在处于负增长的印度空调市场一枝独秀? Q2季度美智能手机出货量达3190万部，苹果市场份额飙升 Silicon Designs推出可提供七种量程选择的MEMS直流响应加速度计 无线传感器网络吞吐量的自适应跨层优化策略 这款传感设备简直就是家庭用电小帮手 OMEGA微型低高度张力传感器的特性参数解析 中兴通讯进军新能源汽车领域 他们是这样造车的 PC机的MPEG-4编码原理及实现 车身稳定系统的作用及组成 [组图]MC34262系列PFC控制芯片的应用研究 用毫米波传感器为汽车带来高级视觉 CC2431的无线传感器网络在温室环境监控系统中的应用 文章排行 PWM调光技术详解 自制充电宝最简电路方案设计汇总 太阳能路灯设计中超级电容的应用 磷酸铁锂电池工作原理详细图解 三端可调输出稳压器应用技巧 燃料电池：下一代移动设备电源 TPS40210异步升压电源控制方案 电池充电电路 KDPExpert专家系统的设计与使用指南（续） 单相半波整流电路的工作原理及参数计算 栏目更新 反激电源变压器设计(二) 反激电源PCB设计总结 浅谈 M3P 电池的性能优势和研发壁垒 双界面散热结构IGBT的热测试方法与结果分析 三极管放大电路设计要求及注意事项 反激电源变压器设计(一) 6W电源管理芯片——U9513D I2C上拉电阻如何根据开发要求选择合适的阻值呢？ 磷酸铁锂电池结构与工作原理 磷酸铁锂电池的优点 正负电源的硬件选择与电路设计 Top