16-Bit 500kSPS 8-Channel Single-Supply SAR ADC-TI ADS8688
The ADS8684 and ADS8688 are 4- and 8-channel, integrated data acquisition systems based on a 16-bit SAR ADC, operating at a throughput of 500 kSPS. The devices feature integrated analog front-end circuitry for each input channel with overvoltage protection up to ±20 V, a 4- or 8-channel multiplexer with automatic and manual scanning modes, and an on-chip, 4.096-V reference with low temperature drift. Operating on a single 5-V analog supply, each input channel on the devices can support true bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, as well as unipolar input ranges of 0 V to 10.24 V and 0 V to 5.12 V. The gain of the analog front-end for all input ranges is accurately trimmed to ensure a high dc precision. The input range selection is software-programmable and independent for each channel. The devices offer a 1-MΩ constant resistive input impedance irrespective of the selected input range.
The ADS8684 and ADS8688 offer a simple SPI-compatible serial interface to the digital host and also support daisy-chaining of multiple devices. The digital supply operates from 1.65 V to 5.25 V, enabling direct interface to a wide range of host controllers.
The key features of ADS8688
1.16-Bit ADC with Integrated Analog Front-End
2.4-, 8-Channel MUX with Auto and Manual Scan
3.Channel-Independent Programmable Input Ranges:
4.5-V Analog Supply: 1.65-V to 5-V I/O Supply
5.Constant Resistive Input Impedance: 1 MΩ
6.Input Overvoltage Protection: Up to ±20 V
7.On-Chip, 4.096-V Reference with Low Drift
ADS8688 16-bit eight-way integrated analog output module block diagram for PLC
The description of ADS8688EVM-PDK Evaluation Module
The ADS8688EVM-PDK is a platform for evaluating the ADS8688 device. The ADS8688EVM-PDK consists of an ADS8688EVM board and an SDCC controller card. The SDCC is an FPGA-based controller card that functions as an serial peripheral interface (SPI™) host and transfers data to the ADS8688EVM graphical user interface (GUI) via a USB interface. The ADS8688EVM GUI collects, analyzes, and records data from the ADS8688EVM board. The ADS8688EVM GUI is capable of collecting data from the ADS8688EVM in auto and manual modes, configuring the ADC program registers, and performing FFT analysis of data captured from the ADC.
The key features of ADS8688EVM-PDK Evaluation Module
• Includes support circuitry as a design example to match ADC performance.
• 3.3-V slave SPI.
• Serial interface header for easy connection to the SDCC controller card.
• Designed for a 5-V analog supply.
• Integrated 4.096-V voltage reference.
• Bipolar (±10.24 V, ±5,12 V, ±2.56 V )or unipolar(0 V to 10.24 V, 0 V to 5.12 V) input ranges for each channel.
• Onboard, second-order, Butterworth, low-pass filters for four channels.
• Onboard regulator for generating a ±15-V bipolar supply for second-order, Butterworth, low-pass filters.
• Capable of accepting a ±100-mV signal on the negative analog inputs (AIN_xGND).