GXSC Analog-to-Digital Converter Replaces AD7980 in Process Instrumentation

Industrial process instruments serve as the core sensing and measurement/control terminals in industrial settings, primarily responsible for the long-term, continuous acquisition, precise quantification, and regulation of process parameters such as temperature, pressure, flow, level, concentration, current, and voltage. The system consists of a front-end sensing unit, a signal conditioning unit, an analog-to-digital conversion and acquisition unit, a main control and processing unit, and an output and interface unit.

Various process physical parameters are converted by sensors into standard analog voltage or current signals. After undergoing impedance matching, amplification, shaping, and noise filtering via precision operational amplifiers, these signals are fed into a high-precision ADC for analog-to-digital quantification. The main control unit then performs digital filtering, temperature compensation, linear calibration, and parameter calculation on the sampled data. Industrial process parameters are often slowly varying, weak signals; even minor parameter fluctuations directly affect process quality, requiring a high-resolution ADC to accurately quantify subtle changes. This paper recommends using the GXSC single-channel 16-bit 1 MSPS analog-to-digital converter to replace the AD7980 in process instrumentation applications.

The GXSC analog-to-digital converter is a 16-bit successive approximation ADC that can be powered by a single VDD supply. It incorporates a low-power, high-speed 16-bit sampling ADC and a versatile serial interface port. On the rising edge of the CNV signal, it samples the analog input IN, which is grounded and ranges from 0 V to REF. The reference voltage REF is applied externally and can be set independently of the supply voltage VDD. Its power consumption varies linearly with throughput.

GXSC Analog-to-Digital Converter Features:

Zero-latency architecture, 16-bit resolution, no missing codes

INL: Typical ±0.6 LSB, Maximum ±1.25 LSB

Dynamic range: 92 dB, VREF = 5 V

Signal-to-Noise Ratio (SNR): 91.5 dB, fIN = 10 kHz, VREF = 5 V

Total Harmonic Distortion (THD): −114 dB, fIN = 10 kHz, VREF = 5 V

Signal-to-Intermodulation-and-Noise Distortion Ratio (SINAD): 91 dB, fIN = 10 kHz, VREF = 5 V

Low Power: Operates on a single 2.5V supply; supports 1.8V/2.5V/3V/5V

Proprietary Serial Interfaces: SPI/QSPI/MICROWIRE™/DSP compatible

Package: MSOP-10, LFCSP-10

Wide Operating Temperature Range: −40°C to 125°C

The SPI-compatible serial interface of the GXSC ADC also features the ability to cascade multiple ADCs on a single 3-wire bus using SDI inputs and provides an optional busy indicator. It is compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic using a separate VIO power supply.