时钟电路原理-电测与仪表.DOC

智能电表时钟问题分析与对策 钱立军 （210016） 摘要：RTC芯片和SoC芯片两种方案，从电路原理、关键器件选型、电池放电曲线、PCB布板可靠性以及生产工艺等方面分析了各种潜在风险。并且就两种方案存在的风险点提出了相应的解决对策：在供电回路选用低反向漏电流的二极管，提高时钟电池的寿命；增加电池激活电路，解决电池电压滞后现象；对时钟电路PCB布板提出了走线及布局等方面的原则；在软件层面提出设计规范性和测试覆盖性等原则；对生产工艺环节提出关键工艺质控点。本文从硬件、软件、生产工艺、质量体系等多角度对电表时钟可能故障提出了预防及解决方案。 关键词： 中图分类号：TM933 文献标识码：B 文章编号：1001-1390（201）00-0000-00 roblem Analyses and Countermeasures of the Real Time Clock in Smart Meters QIAN Li-jun (Jiangsu Provincial Electric Power Company, Nanjing 210016,China) Abstract：With the of smart meters, the meter failure caused by the clock problems has attracted great attention of the whole society, so it is very important to ensure the reliability and accuracy of the clock in the smart meter. This paper analyzed and summarized the typical clock problems of the smart meter, analyzed various potential risks of the RTC chip and the SoC chip used in the smart meter from the circuit principles, selection of key components of the clock, the battery discharge curve, PCB layout reliability and manufacturing processes, and offered correspondingsolutions to the risks involved in the use of the two different chips. The diode with low reverse leakage current could be used to increase the clock battery life; the battery activation circuit could be increased to solve the battery voltage hysteresis；the principles and rules of lines and layout were proposed for the reliability of PCB in the RTC part; principles concerning strict norms of the design and software test coverage areas were put forward on the software level;, and the key points of quality control were suggested to follow in the manufacturing process. This paper provided some precaution and solution schemes for possible malfunctions of the clock in the smart meter , in terms of hardware, software, manufacturing processes and quality systems. Key words： 0 引 言 1　 实时时钟（以下简称时钟）电路的原理如图1所示。从图中可以看出，时钟电路的工作电源有两种模式：一种是市电模式，时钟芯片通过主电源V1供电；另一种是备用电池模式，时钟芯片通过备用电池BAT供电；两路电源通过二极管D1和D2后并联。为确保从市