Is there a faster way to complete the design?
If time is tight, a fully integrated AFE, such as the AD7124 or AD4130 Σ-Δ ADC (with integrated PGA), might be a better choice. Let's say you're designing a sensor for an application requiring thermocouples. In this case, the MAX31855 is a ready-to-use thermocouple-to-digital converter IC that also performs linearization and cold junction compensation. If you're planning an RTD-based sensor, consider the MAX31865 RTD-to-digital converter IC. If you don't have time to research different types of sensors and simply want to design a sensor that provides fast and accurate digital temperature readings, the MAX31875 or ADT7420 digital temperature sensor ICs offer an ideal "one-stop" solution. These devices integrate the sensor, AFE, and linearization circuitry into a single package and connect to a microcontroller via I2C. Figure 1 illustrates several different options.
What are the options for pressure sensors?
Strain gauges and load cells are commonly used to generate electrical signals in pressure sensors, and the AD7124 and AD4130 AFE can also support these sensors. Alternatively, if you do not want the microcontroller to perform linearization, you can use the ADA4558 bridge signal conditioner IC to handle linearization (Figure 2).
How have sensors traditionally been connected to industrial networks?
Typically, sensors are designed to communicate using a single fieldbus or industrial Ethernet protocol. However, this approach requires an internal network interface IC, significantly increasing costs and limiting the sensor's applicability to customers using that protocol. To use the sensor on another network, it must be redesigned with a different interface IC, which is costly and time-consuming. Furthermore, the number and type of diagnostic functions vary depending on the network type (some networks lack diagnostics altogether), and if your sensor only supports a certain protocol, customers may find it difficult to maintain or troubleshoot the sensor after installation. Therefore, sensors should ideally be designed to adapt to any industrial network, reducing costs and expanding the market.
How can sensors be made "network-independent"?
You can achieve this using IO-Link®, a three-wire industrial communication standard designed to connect sensors and actuators to industrial control networks. In IO-Link applications, the transceiver acts as a physical layer interface, connecting to a microcontroller running a data link layer protocol, while supporting digital inputs and outputs (up to 24V). The advantage of IO-Link is its ability to support the transmission of four different types of information: process data, value status, device data, and events. This information can indicate sensor faults, facilitating rapid fault location. The MAX14828 is a low-power IO-Link slave transceiver available in a (4mm x 4mm) 24-pin TQFN package and a (2.5mm x 2.5mm) wafer-level package (WLP), usable over an extended temperature range of -40°C to +125°C.
How do IO-Link slave transceivers communicate with industrial networks?
The IO-Link slave transceiver communicates with the IO-Link master (via cable), while the master connects to the industrial network via a protocol interface IC (such as the ADIN2299 for Industrial Ethernet). The MAX14819A is a low-power, dual-channel IO-Link master transceiver with a sensor/actuator power controller, fully compliant with the newly released IO-Link and binary input standards and test specifications, namely IEC 61131-2, IEC 61131-9 SDCI, and IO-Link 1.1.3.
