SBAS813 June 2018 ADS8688AT
PRODUCTION DATA.
The application circuit and system diagram for this design is illustrated in Figure 120. This design includes a complete hardware and software implementation of a multichannel data acquisition system for power automation applications.
This system can be designed using the ADS8688AT, which is a 16-bit, 500-kSPS, 8-channel, multiplexed input, SAR ADC with integrated precision reference and analog front-end circuitry for each channel. The ADC supports bipolar input ranges up to ±10.24 V with a single 5-V supply and provides minimum latency in data output resulting from the SAR architecture. The integration offered by this device makes the ADS8688AT an ideal selection for such applications, because the integrated signal conditioning helps minimize system components and avoids the need for generating high-voltage supply rails. The overall system-level dc precision (gain and offset errors) and low temperature drift offered by this device helps system designers achieve the desired system accuracy without calibration. In most applications, using passive RC filters or multi-stage filters in front of the ADC is preferred to reduce the noise of the input signal.
The software algorithm implemented in this design uses the discrete fourier transform (DFT) method to calculate and track the input signal frequency, obtain the exact phase angle of the individual signal, calculate the phase difference, and implement phase compensation. The entire algorithm has four steps: