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小功率便携式电子产品,目前常用锂电池和Boost(Buck)芯片给MCU、Audio以及显示屏等器件供电。此类产品通常使用适配器供电,设计要求充电部分工作时,必须通过测试并符合EMC标准。一般来说,为了提高系统工作效率,锂电池充电芯片都是基于开关工作方式,类似一个开关电源;另外,可能其他的开关电源芯片在同时工作,器件均为开关工作方式,提高了工作效率,同时引入了辐射问题,这也是电子产品设计过程中的常见问题。本文基于一个产品设计实例(用BQ24133单电池充电电路和LM3478升压电路),对设计过程中曾经遇到的辐射难题进行了详尽的分析。确定骚扰源,找出耦合路径,最终给出解决问题的方法,以供大家作参考。
Low-power portable electronic products, commonly used lithium batteries and Boost (Buck) chip to MCU, Audio and display devices such as power supply. Such products are usually powered by adapter, the design requirements of the charging part of the work must pass the test and comply with EMC standards. In general, in order to improve system efficiency, lithium battery charging chips are based on the switch mode of operation, similar to a switching power supply; In addition, other switching power chips may work at the same time, the devices are switching mode of operation, improve work efficiency, At the same time the introduction of the radiation problem, which is also a common problem in the electronic product design process. This article based on a product design example (BQ24133 single-cell charging circuit and LM3478 boost circuit), the design process encountered in the radiation problems were analyzed in detail. Determine the source of harassment, find the coupling path, and ultimately give a solution to the problem, for your reference.