应用中使用了ADS1254 AD芯片，VREF= 5 V
CH1- 接2.5V
CH1+ 介于0V--5V之间
当CH1+ 大于 CH1-时，AD采样结果正确无误，但是当CH1+ 小于CH1-时，AD采样结果却不对了，且无论我怎么改变CH1+的电压，只要是CH1+小于CH1-，
采样结果基本不变，如下所示？
EnvTemp = 23.07,AdCode = 07 e5 3f AdValue = 0.308
EnvTemp = 23.07,AdCode = 07 e4 a9 AdValue = 0.308
EnvTemp = 23.07,AdCode = 07 e5 69 AdValue = 0.308
EnvTemp = 22.91,AdCode = 07 e4 c3 AdValue = 0.308
EnvTemp = 23.48,AdCode = 07 e4 92 AdValue = 0.308
EnvTemp = 23.48,AdCode = 07 e4 73 AdValue = 0.308
EnvTemp = 22.99,AdCode = 07 e4 f8 AdValue = 0.308
EnvTemp = 22.99,AdCode = 07 e5 38 AdValue = 0.308
采样结果居然是一个0.31V 左右的值？
不解，请各位朋友帮忙分析分析。谢谢
