Replacing the ADS1248 with the GXSC ADC in High-Precision Measurement Instruments

High-precision measurement instruments are critical devices for acquiring measurement data, ensuring product quality, and driving technological innovation. The primary tasks of these instruments include capturing microvolt-level signals, milliohm-level resistance changes, and millivolt-level bridge outputs, which place high demands on the resolution, noise level, stability, and integration of front-end analog-to-digital conversion components. This article recommends the use of a GXSC 24-bit, 8/4-channel, 2kSPS analog-to-digital converter. This chip is 100% hardware and software compatible with the ADS1248, allowing for direct replacement on the board, which facilitates rapid implementation of the replacement and reduces development costs.

The GXSC ADC incorporates numerous integrated features designed to reduce system costs and component count in sensor measurement applications. The device features a low-noise, programmable gain amplifier (PGA), a precision differential ADC with a single-cycle-stable digital filter, and an on-board oscillator. Its high level of integration significantly reduces instrument size and simplifies power supply design. With a wide supply voltage range (2.7 V to 5.25 V) and low power consumption (typically 2.3 mW), it is well-suited for battery-powered handheld portable instruments, extending battery life.

The GXSC ADC incorporates a low-drift voltage reference and two matched programmable current sources (IDACs). A single input multiplexer supports four differential inputs. Additionally, this multiplexer integrates sensor burnout detection, thermocouple voltage bias, system monitoring, and general-purpose digital I/O functions. The PGA provides selectable gain up to 128 V/V. These features offer a complete front-end solution for temperature sensor measurement applications, including thermocouples, thermistors, resistance temperature detectors (RTDs), and other small-signal measurement methods such as resistive bridge sensors.

The digital filter in the GXSC ADC stabilizes within a single cycle, enabling fast channel switching when using the input multiplexer and supporting data rates up to 2 kSPS. For certain data rates, the filter is capable of rejecting interference at both 50 Hz and 60 Hz.