Схемы, платы, компоненты

вот какое есть описание в руководстве на АЦП

The ADC has two ranges: 2.4V and 3.6V. 
In 2.4V range mode, the maximum input signal amplitude is ±2.4V; 
in 3.6V range mode, the maximum input signal amplitude is ±3.6V. 

When the ADC sampling channel is set as the output signal of the OPA (i.e. OPA0 ~ OPA1), 
the appropriate OPA gain should be selected. This will allow the maximum signal 
in a specific application to be amplified to a level close to +/-3.3V, while setting the ADC to a 3.6V range. 

For example, the maximum phase current is 100A (effective value of sine wave), 
and the MOS internal resistance (assuming as MOS internal resistance sampling) is 5mR, 
then the maximum input signal amplitude of the OPA is +/-707mV. 
Then, the OPA gain should be selected to be 4.5 times (see 5.2.5 for gain selection method), 
and the amplified signal is about +/-3.18V. 
If the output signal of the OPA is amplified and the maximum signal is still less than +/-2.4V due to objective reasons, 
the range of the ADC should be set to 2.4V. 

When the ADC sampling channel is set as the input signal of the GPIO multiplex port, 
the ADC range is also selected according to the maximum amplitude of the signal. 
Due to the limitation of the IO port, the signal range of the GPIO multiplex port can only be between -0.3V ~ AVDD+0.3V.