ADS8681: Timing of acquiring the analog input signal

Hi Yuto,

The acquisition starts when the ADC mode is moving from the conversion phase to the acquisition phase. In your timing diagram,it's the end of tconv and the beginning of tacq. The moment you highlighted indicates that the conversion starts.

Thanks&Regards,

Dale

Hi Yuto-san,

No, the analog signal acquired in previous cycle is used in conversion period of current cycle which starts at the rising edge of CONVST/CS you highlighted.

When acquisition phase starts (rising edge of ADCST and the end of tconv and the beginning of tacq), the internal switch S1 is closed, the internal sampling-hold capacitor will be charged, see screenshot below:

When conversion phase starts (at the rising edge of CONVST/CS), the internal switch S1 is open, the internal circuitry will start conversion, see screenshot below:

These detailed information can be found in SAR Operation Overview - SAR ADC Input Driver Design of TI Precision Labs - ADC.

Thanks&regards,

Dale