串行模数转换器MAX1072/MAX1075的原理及应用

MAX1072/MAX1075是Maxim公司推出的10位串行输出模数转换器,具有真差分输入、高转换速度、低功率损耗等特点,广泛应用于各种传感器测量电路.给出了MAX1072/MAX1075的内部结构、功能特点和工作原理,并详细描述了在温度测量系统中的典型应用和使用注意事项.     

基于看门狗芯片MAX708的数据保护系统设计

单片机系统的设计要考虑程序的稳定性和数据的安全性,如果连续运行或环境恶劣,用软件看门狗不起作用时,往往要使用硬件看门狗来重启CPU,如果断电,常常还有一些重要的数据要保护。针对这些问题,给出了既有电源监控和数据保护又有看门狗作用的集成电路MAX708。介绍了MAX708的原理及在数据保护方面的应用,给出了MAX708与微处理器的接口及其作为电源监测和数据保护使用时的部分程序框图。该系统可以有效解决单片机系统运行的稳定性和数据的安全性。     

12位A/D转换器MAX187原理及应用

MAX187是一个具有串行接口的12位A/D转换器。设计精巧,工作速度快。小巧的封装,外围电路简单,特别适合于高精度小型便携式仪器设备中使用。详细介绍了MAX187的特点及工作原理、操作时序,给出了MAX187与AT89C51单片机的接口电路,并介绍其在直流电压测量系统的应用和基于MCS-51的汇编语言程序。     

基于SP37的新型TPMS系统设计

简要介绍了胎压监测系统(TPMS)的组成,提出了一种基于新型传感器SP37的胎压监测系统.该系统采用SP37和MAX1473作为无线收发芯片,详细阐述了其软件和硬件设计中的关键技术.实际测试效果表明,该系统接收灵敏度可达到-100 dBm,高速跑车时速100 km时工作稳定.     

MAX7219在数码管显示电路中的应用研究

传统的数码管显示电路,需占用较多的单片机口线,采用动态扫描方式编程时较为复杂,为解决此类问题,作者介绍了一款数码管显示专用驱动芯片MAX7219,MAX7219采用串行方式与单片机通信,仅占用3条口线,同时,片内集成硬件动态扫描显示控制电路,支持软件修改内部参数以实现数码管的自由显示,文章设计了MAX7219驱动8位数码管的应用电路,提供了程序代码。实验表明,MAX7219可较大程度地简化电路,提高集成度,增强系统的可靠性,是一款优秀的LED数码管显示驱动器件。     

基于CPLD的多通道数据采集系统

数据采集技术是信息科学的一个重要分支,与传感器技术、信号处理技术、计算机技术共同构成了现代检测技术的基础.详细介绍了数据采集系统的设计方案、组成结构及其特性.该采集系统由采样保持器、AD转换器、CPLD、USB控制芯片、软件设计等组成.采用Altera公司的EPM7128芯片为控制器的核心器件,设计了一种基于CPLD的...     

基于MAX16832C驱动器的大功率LED电源

大功率LED是一种新型的半导体光源,具有效率高、寿命长、环保等优点。基于MAX16832C芯片设计了一款高精度LED恒流源驱动电路。MAX16832C是降压型恒流高亮度LED驱动器,为汽车内部或外部照明、建筑和环境照明、LED灯及其他LED照明应用提供极具成效的解决方案。本设计以CREE公司的Q4型大功率白光LED为负载,供电电源为输出电压为24 V的太阳能光伏电池。测试结果表明该电路满足大功率白光LED照明的电压电流工作要求。     

Microstructure and phase transformation of Ti3AC2 (A = Al,Si) in hydrofluoric acid solution

In this paper, Ti₃AC₂ (A = Al, Si) were prepared by pressureless argon shielding synthesis technique. The microstructure and phase transformation of as‐prepared Ti₃AC₂ (A = Al, Si) in hydrothermal hydrofluoric acid (HF) solution were investigated systematically. Results showed that the obtained Ti₃AlC₂ and Ti₃SiC₂ were closely aligned layered structure. In hydrothermal HF solution, Al or Si element was preferentially etched from the layered structure, inducing obvious transformation of microstructure and phase composition. For Ti₃AlC₂, Al atoms diffused out of the structure and reacted with HF to form AlF₃•H₂O, which induced the rearrangement of the Ti and C atoms, and finally resulted in the formation of TiC_x cubic phase. With the hydrothermal temperature and reaction time increasing, the TiC_x phase gradually disappeared and the grain size of AlF₃•H₂O gradually increased. When Ti₃SiC₂ was immersed in hydrothermal HF solution, the main products were TiC and SiC. Interestingly, with the hydrothermal treatment temperature and reaction time increasing, TiC gradually disappeared, while SiC nearly kept unchanged. This can be explained that SiC was covalently bonded carbide, while TiC was metallically bonded, having relatively weak bond energy and consequently being unstable in hydrothermal HF solution.     

First‐order Raman scattering of the MAX phases: Ti2AlN,Ti2AlC0.5N0.5, Ti2AlC, (Ti0.5V0.5)2AlC,V2AlC,Ti3AlC2, and Ti3GeC2

Here, we report, for the first time, on the Raman spectra of Ti₂AlN, Ti₂AlC_0.5N_0.5, (Ti_0.5V_0.5)₂AlC, Ti₃AlC₂, and Ti₃GeC₂ and compare the results with those of Ti₂AlC and V₂AlC reported previously. The first‐order mode peaks of the end members are narrower than those of their respective solid‐solution compounds. The Ti₃AlC₂ and Ti₃GeC₂ phases show, in addition to atomic displacements of the ‘M’ and ‘A’ atomic planes, modes that correspond with vibrations of the ‘X’ sublattice relative to itself. We also predict the Raman modes using density functional theory. The agreement between theory and experiment was found to be satisfactory. Copyright © 2011 John Wiley & Sons, Ltd.     

基于RS-485的小区安防信息采集控制系统的设计

为解决当前住宅小区安防信息采集的问题,提出一种智能小区安防信息采集控制系统的设计方案.该方案基于RS-485接口协议标准构造,采用MAXIM公司的MAX487构造小区信息联网卡网络,通过联网卡接口将小区终端管理系统与用户室内控制系统相连,实现对居民家中火警、煤气泄露、非法入侵等各种意外事件的实时数据采集,并对相应报警信息进行及时处理.该系统安全性能好,成本较低,可操作性强,便于推广.