Monitoring an industrial system—such as building automation or industrial networking equipment—is essential to ensure continuous operation. You'd want to know, for instance, whether the voltage in your system is set at the right threshold, or if a relay contact is present. However, system monitoring usually requires an external isolated power supply. Such power supplies can consume a lot of space and also be quite costly, especially when the power demand on the field size is small.
Among the advantages isolated power supplies bring are their ability to protect electronic loads as well as equipment operators from exposure to high voltages, along with their ability to prevent ground loops. However, for industrial systems whose components are getting smaller, the size of isolated power supplies is disadvantageous. For these types of systems, how can you simplify your diagnostics scheme while still meeting the size constraints? In this blog post, we'll discuss the challenges you might encounter in both powering and monitoring an industrial system, and introduce a new digital isolator that can help you overcome the challenges.
Figure 1. Industrial networking applications can benefit from solutions that provide diagnostic system monitoring.
Intelligence at the Edge Requires Small, Power-Efficient ICs
Let's consider industrial networking as an example application area to illustrate our points. Thanks to industrial networking technologies, factories, for instance, are becoming smarter and more autonomous. Intelligence is moving to the edge and enabling real-time decision-making that is helping to boost manufacturing uptime and productivity. Eventually, the machines will become self-aware enough to perform predictive maintenance or diagnoses and repairs with minimal human intervention. Enabling this drive toward true industrial convergence are underlying industrial power and industrial communications ICs that are power efficient, rugged, and small enough to fit at the edge.
In keeping with these trends, system monitoring is also moving toward more compact, integrated, and cost-efficient solutions. After all, integrating a large external isolated power supply into such an environment isn't practical. Transformers are traditionally used for power isolation, plus optocouplers or digital isolators for the data isolation barrier. This mix of discrete components takes up a significant amount of board space that wouldn't fit well in an industrial networking architecture.
A new self-powered, two-channel digital isolator provides isolated system monitoring and enhanced system diagnostics, while reducing solution size by 4x and component count by 5x compared to traditional discrete approaches. The MAX22518 provides:
- Integrated isolated power (3.3V at 220µA)
- 3.5kVRMS galvanic isolation
- Two binary inputs with field protection
- <10mA logic supply consumption
- 3.0V to 5.5V logic supply voltage
- -40°C to +125°C operating temperature range
Because the device's 220µA field-side power is supplied by the logic side using an integrated, isolated DC-DC converter, there's no need for a bulky, expensive external isolated power supply when the power demand from the field side is small. It provides enough power for small field-side circuits like window comparators and relay monitoring circuits. The key to the device's ability to simplify diagnostic monitoring while it also delivers isolated power is the MAXSafe system architecture. MAXSafe is the industry's first integrated isolated micropower architecture, providing enough power for internal chips and a simple field-side circuit in a design. Self-diagnostics and monitoring happen on the isolated field side. Functionality and status can be communicated over isolated circuitry to the design's microcontroller. Isolated diagnostics ensure robust communications.
Figure 2. This diagram provides an example of dry contact remote alarm sensing and monitoring using the MAX22518 digital isolator
With these features, the MAX22518 is ideal for dry contact remote alarm monitoring, such as ethernet switches and industrial IoT applications (Figure 2), and for isolated field supply window monitoring, such as motor DC bank, battery bank, AC input, and negative supply designs. A traditional system monitoring solution based on discrete devices (dual optocoupler, dual discrete binary inputs, isolated power) would require up to 15 components and a solution size up to 178mm2. By comparison, the MAX22518 is only 44mm2 and requires just three components. This helps the designers to reduce board space and bill of materials.
For applications requiring analog-to-digital converters, consider the MAX14001 configurable, isolated 10-bit ADC, also designed with the MAXSafe architecture. The MAX14001 also features programmable voltage comparators and inrush current control for configurable binary input applications.
Watch for more MAXSafe products in the future, as Maxim continues to find ways to simplify diagnostic monitoring while reducing the size of your industrial system solution.