Replacing the AD7689 with the GX7689 8-Channel 16-Bit 250 kSPS Analog-to-Digital Converter for Multi-Channel System Monitoring

Multi-channel system monitoring is commonly used in industrial automation and process control to acquire and monitor multiple sensor signals in real time. Traditional discrete solutions generally have high power consumption and material costs, while the multiplexed architecture shares a single ADC core, minimizing the conversion cost and space occupation per channel. This application solution can use the GX7689 8-channel 16-bit charge redistribution successive approximation register (SAR) analog-to-digital converter.

The GX7689 has all the components required for a multi-channel low-power data acquisition system, including: a true 16-bit SAR ADC with no missing codes; an 8-channel low-crosstalk multiplexer for configuring the inputs as single-ended, differential, unipolar, or bipolar inputs; an internal low-drift bandgap reference (selectable 2.5 V or 4.096 V) and buffer; a temperature sensor; a selectable single-pole filter; and a sequencer that is very useful when multiple channels are sampled sequentially and continuously.

The GX7689 uses a simple SPI-compatible interface to write configuration registers and read conversion results. The digital interface uses a separate supply (VIO) set to the logic level. Power consumption is proportional to the sampling rate. The GX7689 features are as follows:

Throughput rate: 250 KSPS

16-bit resolution, no missing codes

Integral nonlinearity: typical ±0.8 LSB, maximum ±1.6 LSB

Dynamic range: 88 dB

Signal-to-noise and distortion ratio: 87 dB @ 2 kHz

Total harmonic distortion: -100 dB @ 2 kHz

Internal reference: 2.5 V/4.096 V selectable

External buffered reference: up to 4.096 V

External reference: up to VDD

Supports single analog supply VDD: 3.3 V to 5.5 V

Logic interface supply VIO: 1.8 V to 5.5 V

Channel sequencer

Internal temperature sensor

8-channel multiplexer with configurable input modes