Replacing the ADS1278 with the GXSC A/D Converter for Multi-Channel Strain Testing

Strain testing is a technical method used to determine a structure’s stress distribution, deformation state, and operational reliability. It primarily relies on the piezoresistive effect of resistive strain gages for measurement. When a strain gage is affixed to the surface of the structure under test, the gage’s resistance undergoes a slight change in tandem with the structure’s deformation under load. A bridge circuit converts this change in resistance into a weak analog voltage signal.

Strain testing signals are typically weak analog signals that are susceptible to environmental electromagnetic interference and channel timing deviations. This solution recommends using the GXSC 8-channel 400 ksps 24-bit analog-to-digital converter. This chip offers pin-to-pin replacement for the ADS1278 and meets the technical requirements of multi-channel strain testing applications.

The GXSC ADC employs a high-order multi-bit delta-sigma modulator. In-band noise is shaped and then filtered out via an on-chip digital decimation filter, resulting in extremely low in-band noise power. The chip offers two on-chip digital filter options: a high-bandwidth FIR filter, with an effective bandwidth reaching 90.6% of the Nyquist bandwidth and in-band ripple less than ±0.005 dB; and a low-latency SINC filter, which can generate stable data output within 6 cycles and offers superior noise performance.

The GXSC ADC is controlled directly via PIN pins, eliminating the need for register configuration and making it user-friendly for developers. It employs a high-order multi-bit delta-sigma modulator, which shapes the in-band noise and then filters it out using an on-chip digital decimation filter, resulting in extremely low in-band noise power. Its features are as follows:

• 8-channel synchronous sampling with data rates ranging from 144 kS/s to 400 kS/s

• Selectable high-bandwidth FIR filter or low-latency SINC filter

• Low power consumption: HS mode: 34.0 mW/channel;

HR mode: 20.8 mW/channel;

LP mode: 10.9 mW/channel;

LS mode: 2.7 mW/channel;

• Rail-to-rail input common-mode voltage

• Common-mode rejection ratio: 116 dB

• Analog supply: 5 V; Digital supply: 1.8 V

• I/O supply: 1.8 V to 3.3 V

• SPI or frame-synchronous interface, supports daisy-chain mode

• ESD rating: HBM ±2 kV, CDM ±2 kV; Latch-up ±600 mA

• Operating temperature range: -40°C to +85°C