ADC GX7793 is compatible with AD7793 for use in industrial environments as a gas-sensitive sensor.

Gas sensors are devices used to detect gas concentration and composition, primarily in environmental protection and safety monitoring applications. These sensors are exposed to various gas components and operate under harsh conditions, such as significant fluctuations in temperature and humidity, as well as the presence of dust and oil mist. Additionally, gases can react chemically with the sensor element materials, causing deposits on the surface that degrade performance.

Therefore, gas sensors must be capable of detecting the permissible concentration of alarm gases and other standard gas concentrations, operate stably over the long term, exhibit good repeatability, respond quickly, and be minimally affected by coexisting substances. This paper recommends the use of the GXSC 24-bit Σ-Δ ADC GX7793, which is pin-to-pin compatible with the AD7793, helping to reduce development costs while maintaining excellent performance.

Solution application principle: By converting gas type and concentration-related information into electrical signals via analog-to-digital conversion, the strength of these electrical signals can be used to obtain information about the presence of the target gas in the environment, enabling detection, monitoring, and alarm functions. Additionally, an interface circuit can be used to integrate with a computer to form an automatic detection, control, and alarm system.

The GX7793‘s low power consumption and low noise characteristics make it ideal for high-precision measurement applications. The chip includes three differential analog inputs and integrates an on-chip low-noise instrumentation amplifier, enabling direct input of small signals. The GX7793 can operate using an internal clock or an external clock, and the output data rate can be programmed via software, ranging from 4.17 Hz to 940 Hz.

Key features of the GX7793:

• Operating voltage range: 2.7V to 5.25V

• Root Mean Square (RMS) noise: 38nV (at 4.17Hz); 79nV (at 16.7Hz)

• Power consumption: 360 µA in operating mode

• Supports 15 update rates: 4.17 Hz to 940 Hz

• Gain settings: 0.5/1/2/4/8/16/32/64/128 times selectable

• Built-in RCO circuit with default frequency of 64K  

• Built-in programmable current source and bias voltage generator  

• TSSOP-16 package  

• SPI communication interface  

   Supports standard 3-wire SPI interface  

   Supports up to 5M SCLK communication clock  

   Supports CRC and XOR checksum verification