Application of GXSC 24 bit 16kSPS analog-to-digital converter GX7124 replacing AD7124 in thermocouples

Thermocouples are widely used in the field of temperature monitoring, with a wide temperature measurement range, good stability, and resistance to harsh environments. However, the thermoelectric potential signal output by thermocouples is extremely weak (usually only tens to hundreds of microvolts) and is easily affected by environmental noise, wire impedance, cold end temperature drift, and other factors. This article mainly introduces a ∑ - Δ analog-to-digital converter GX7124 designed specifically for high-precision analog signal acquisition, which is PIN TO PIN compatible with AD7124. It not only perfectly solves the technical pain points of thermocouple temperature measurement, but also provides a new replacement solution for thermocouple temperature measurement systems.

GX7124 includes many integrated features that can reduce the number of system level components required for sensor measurement applications. Featuring low noise, programmable gain amplifier, ADC, single cycle digital filter and oscillator, low drift reference voltage source, and two matched programmable excitation current sources, the input multiplexer supports eight differential inputs.

In addition, the GX7124‘s multiplexer also integrates sensor burnout detection, thermocouple voltage bias, system monitoring, and universal digital I/O. PGA provides up to 32V/V optional gain, which provides a complete front-end solution for temperature sensor measurement applications, including thermocouples, thermistors, resistance temperature detectors (RTDs), and other small signal measurements, including resistance bridge sensors. The weak signal of the thermocouple is easily drowned out by noise, resulting in temperature measurement errors. It has a 23 bit lossless code resolution, an output rate of up to 16kSPS, linearity<7ppm, and supports 50/60Hz simultaneous suppression, meeting the ultimate precision requirements of high-end industrial temperature measurement.

The main performance advantages of GX7124 are as follows:

• Effective resolution: 23bits

• Number of channels: 16 single ended/8 pairs of differential

• Output rate: up to 19.2kSPS

• High integration:

Integrated internal benchmark: temperature drift 8ppm/℃, 2.5V

› Programmable differential amplifier (integrated high impedance PGA): 0.02% initial accuracy

Integrate 2 channels with 0.1% matching degree IDAC

Integrated Bias voltage and wire breakage detection

Integrated 2 ℃ precision temperature sensor

• Supports 50/60Hz simultaneous suppression

Single cycle establishment and automatic channel scanning

• Support SPI CRC verification

Digital power supply: 2.7V~5.25V

• Analog power supply: unipolar (2.7V~5.25V)&bipolar (± 2.5V)

• Package: 5.00mm x 5.00mm QFN (32pin)

• Operating temperature range: -40 ° C to+125 ° C