When i read register CH0_ERR_REG,i found that:
a、CH0-AINP undervoltage error,CH0-AINM undervoltage error，how can i deal these errors？
If you get these flags, it actually means that both AIN0+ and AIN0- voltages are below the AVSSx - 40mV.
What type of signal are you connecting to that channel and ?
The input signal is ±100mV,AC signal,and i use channel 0 and channel 2.
Follows the chart.
The input signal is ±1.4V,follows as the chart.
Here in your plot, I pressume this is either AIN+ or AIN-, correct? And it is refered to GND, correct?
So, in the negative semiperiod, your signal will be as low as -1.4V, which is below the limit I mentioned above (AVSSx-40mV) and hence the undervoltage triggers.
In fact, if you are willing to acquire this bipolar signal you will need to either use a dual power supply or level shift your input. Note that the absolute input signal on any AINx+/AINx- pin must be kept between AVSSx+100mV and AVDD1x-100mV to avoid lineality degradation.
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