w7500P ADC crosstalk

Hi everyone.
We are developping a measuring device based on the w7500P chip and we are suffering from an interference between channels. It seems once we have sampled one channel, the next sampled channels gets affected by the sampling capacitor´s charge due to previous channel. There is no information about the internal impedance or the external optimum resistance and capacitance required for a “fast” sampling (we are talking about a few kHz, nothing high that justifies the interference). Has anyone suffered from this interchannel crosstalk or influencing?

Besides, does anyone know whar the “Abnormal mode” of the ADC is? It ´s mentioned in the user manual (ADC control register) but not explained.