多通道隔离采集电路设计

Design of multi-channel isolated acquisition circuit

为便于采集不共地的多路信号,防止信号间的串扰,在采集电路基础上增加隔离设计:隔离电源、隔离光耦以及数字隔离通道,大大降低了噪声的干扰,提高了系统的采集精度。基于系统电路设计,分析了隔离电源LTM8068及线性隔离光耦HCNR201的工作原理,建立ROM表实现了采集模块的片选及模拟开关通道的切换,方便控制的同时提高了采集板卡的通用性。实验通过输入0~5 V模拟量验证电路采样精度,经实践验证,该隔离采集电路的采样精度优于2‰,且抗干扰能力强,电路通用性好,具有较强的实用价值。

In order to facilitate the collection of multi-channel signals that do not share the same ground and prevent crosstalk between signals,an isolation design is added on the basis of the collection circuit:isolated power supply,isolated optocoupler and digital isolation channel,which greatly reduces noise interference and improves the collection accuracy of the system.Based on the system circuit design,the working principles of the isolated power supply LTM8068 and the linear isolation optocoupler HCNR201 are analyzed,and the ROM table is established to realize the chip selection of the acquisition module and the switching of the analog switch channel,which facilitates control and improves the versatility of the acquisition board.The experiment verifies the sampling accuracy of the circuit by inputting a 0~5 V analog quantity.After practical verification,the sampling accuracy of the isolated acquisition circuit is better than 2‰,and it has strong anti-interference ability,good circuit versatility,and strong practical value.