基于ADG1607十六通道湿度测量电路设计

Design of Sixteen Channel Humidity Measuring Circuit Based on ADG1607

摘要:

为了解决多路湿度测量各个通道系统误差一致性以及简化ADC电路的问题，采用两片ADG1607电子模拟开关和一片AD7792数模转换器构成信号测量电路，通过MCU控制模拟开关阵列进行切换，实现十六路湿度模拟信号的采集，按照预设的顺序分时送入AD转换为数字量输出，通道切换需要稳定时间，经验值采取10ms。在输入电路加入合适的电阻和电容组成RC滤波电路消除开关切换带来一些毛刺干扰，同时引入正确的放电回路，防止电荷积累而影响测量精度。对电路进行测试，结果表明，各通道之间最大误差为0.17%，通道一致性评价为，相对误差0.003，平均绝对离差0.002475，标准差为0.095。该电路已经在实际的自动气象站中长期应用，无机械触点的模拟电子开关能够很好地适应频繁切换，其整体测量性能指标满足气象观测设备对湿度测量准确度的要求。

Abstract:

In order to solve the problem of system error consistency of each channel of multi-channel humidity measurement and to simplify the ADC circuit, two ADG1607 electronic analog switches and one AD7792 digital-to-analog converter are used to form the signal measurement circuit, and the analog switch array is controlled by MCU to switch, so as to realize the collection of sixteen channels of humidity analog signals, which are sent into AD and converted into digital output according to the preset sequence in time, and the channel switching needs stable time, The empirical value is 10ms. Add appropriate resistance and capacitance to the input circuit to form RC filter circuit to eliminate some burr interference caused by switch switching, and introduce correct discharge circuit to prevent charge accumulation from affecting the measurement accuracy. The circuit is tested. The results show that the maximum error between each channel is 0.17%, the channel consistency evaluation is, the relative error is 0.003, the average absolute deviation is 0.002475, and the standard deviation is 0.095. The circuit has been used in the actual automatic weather station for a long time. The analog electronic switch without mechanical contact can well adapt to frequent switching, and its overall measurement performance index meets the requirements of meteorological observation equipment for humidity measurement accuracy.