Bench Talk

(Source: Analog Devices)

Smart Building and Smart Home are contemporary terms used to describe built structures that employ automated control systems to manage their environment, lighting, security, and other facilities. Smart City is used to describe a larger metropolitan area comprising multiple smart buildings and homes, which may also use elements of these automated systems for larger-scale facilities management (traffic flow, electricity, water treatment, etc.). Commonly referred to as Building Automation and Control Systems (BACS), their goal is to improve operational efficiency by reducing building energy consumption and enhancing its occupants’ safety and comfort. BACS, controlled using digital controllers that closely resemble the Programmable Logic Controllers (PLC) units found in Industrial systems, is made possible through the recent convergence of smart sensors and actuators, networking protocols, and software configurability.

Analog Devices (ADI) building automation system technologies support the explosion of connected devices that enable intelligent buildings. These smaller, scalable, lower power solutions enable a platform approach to building control that monitors, controls, and reconfigures at a local or high level. These solutions fit into existing building network topologies and standards as well as enable cutting-edge builds.

These include (Figure 1):

• Digital and Analog Inputs to monitor a wide array of sensors; temperature, humidity, pressure, etc.
• Digital and Analog Outputs to drive a variety of actuators, damper controllers, solenoids, and valves.
• Communications Interfaces (RS-485, CAN, Home Bus) for data and control signaling isolators for safety and to protect low voltage electronics from high field-side voltages

Figure 1: BACS Key Enabling Technologies (Source: Analog Devices)

In BACS, Analog Input and Output ICs precisely monitor and control the state of continuously varying environmental variables, for example, temperature, humidity, lighting, and gas levels.

Analog Output

The MAX22007 is a 4-channel Analog Output in which designers can independently configure each channel using software to operate in either current or voltage mode. With a factory-calibrated output with a total unadjusted error of <1% from -40C to 85°C, this IC provides better accuracy in a smaller footprint than discrete solutions.

Analog Input

The MAX22005 12-channel industrial-grade analog-input IC can operate in both voltage and current mode. It provides 12 single-ended, six differential, four configurable inputs, or any combination thereof.

Digital Inputs and Outputs are suitable for multiple functions within a BACS, e.g., in a security sub-system monitoring building entrances/exits or as part of a fire detection and sprinkler activation system.

Configurable Digital IO

The single-channel MAX14914 and quad-channel MAX14906 can be configured to operate either as a digital input or as a digital output (high-side or push-pull). Both devices provide space and power savings while offering robust protection against ESD and surges. These ICs integrate several diagnostic features that enhance overall end system reliability.

For safety reasons, double isolation is a regulatory requirement in systems that require direct human contact. Reinforced isolators have the same protective effect as double isolation, making them suitable for use in BACS.

Galvanic Isolators

MAX22344, MAX22345, and MAX22346 are 4-channel, 3.75kV_RMS reinforced low-power digital galvanic isolators that use Analog Devices’ proprietary process technology to provide data transfer rates up to 200Mbps. Two independent voltage supplies operate between 1.71V and 5.5V, providing logic translation and the required galvanic isolation for safety.

Dry Contact/Relay Monitor

The MAX22518 is a dual-channel isolator with an integrated DC-DC converter. Requiring only a single 3.0-5.5V logic-side supply eliminates the need for a bulky and expensive field-side power supply.

8-Channel Relay/Load Driver

The MAX4896 is an 8-channel relay and load driver designed for medium voltage applications up to 50V, driving either latching/non-latching or dual-coil relays. It provides open-load and short-circuit fault detection and protects against inductive kickback and overcurrent conditions. Each independent open-drain output features a 3Ω (typical) on-resistance and is guaranteed to sink 200mA of load current (VS ˃ 4.5V) when all channels are active or 410mA for each channel.

High DC Voltage Monitoring

The MAX22530 family are galvanically isolated, 4-channel, multiplexed, 12-bit analog-to-digital converters (ADC) from the MAXSafe^™ family product line. An integrated, isolated DC-DC converter powers all field-side circuitry enabling field-side diagnostics even without an input signal.

Quad-Channel Low-Side Switch

The MAX14919 is an industrial quad-channel low-side switch with 140mΩ (typical) on-resistance per channel and integrated ±1kV/42Ω surge protection. It has resistor-settable current limiting that provides operating currents in the range of 100mA to 800mA. The outputs can get connected in parallel for higher load currents. The four switches are pin-controlled to allow for fast and straightforward switching of up to 200kHz. Reverse-current detection prevents damage against load-supply miswiring faults, while the switches are short circuit and overload protected. Inductive loads may rapidly discharge using internal high-voltage clamps.

BACnet, Profibus, Modbus, and Home Bus are networking protocols commonly used in BACS. ADI provides a comprehensive portfolio of transceivers to provide robust and reliable data protocol signaling at the physical layer.

RS-485

ADI’s range of RS-485 products includes half-duplex, full-duplex, isolated-data, and fully integrated modules like the MAXM22511 that provide complete data and power isolation in a single package. All transceivers integrate high levels of ESD protection to help reduce board space while maintaining robust performance.

Controller Area Network (CAN)

A controller area network (CAN) is a two-wire, half-duplex, high-speed serial network typically used to provide communications between network nodes that can operate independently of the main system microcontroller. CAN transceivers act as the interface between a controller and the physical wires of the CAN bus. ADI’s portfolio of CAN transceivers, which includes the MAX14883E, provides high ESD and fault protection and polarity selection to reduce downtime caused by installation errors. The MAX14878 contains integrated isolation for enhanced robustness.

Home Bus

The MAX22088 is a Home Bus System (HBS) compatible transceiver that uses a single pair of wires for data and power. This IC eliminates the need for the bulky external AC-blocking inductor typically required in bus-powered applications. It also improves signal quality, enabling longer cable runs (Table 1).

Table 1: Transceiver Product Selector for Building Automation (Source: Analog Devices)

Quad Beyond-the-Rails^® (BTR) Switch

The MAX14777 quad SPST switch supports analog signals above and below the rails with a single 3.0V to 5.5V supply. It has a selectable -15V/+35V or -15V/+15V analog signal range for all switches. Each independent switch is controlled separately, making the device an alternative to opto-relays in applications that do not need galvanic isolation. Alternatively, designers can quickly configure the MAX14777 as a single-supply analog input module that supports both ±15V voltages and 4mA–20mA current measurements. In this scheme, a switched 250Ω resistor translates the loop current to a voltage for analog measurement.

ADI’s industrial communication products provide building automation engineers with a broad range of analog IO, digital IO, isolation, and communication interfaces that combine low power, robust performance, and improved diagnostics in the smallest possible form factors.

Paul Golata joined Mouser Electronics in 2011. As a Senior Technology Specialist, Paul contributes to Mouser’s success through driving strategic leadership, tactical execution, and the overall product-line and marketing directions for advanced technology-related products. He provides design engineers with the latest information and trends in electrical engineering by delivering unique and valuable technical content that facilitates and enhances Mouser Electronics as the preferred distributor of choice.

Before joining Mouser Electronics, Paul served in various manufacturing, marketing, and sales-related roles for Hughes Aircraft Company, Melles Griot, Piper Jaffray, Balzers Optics, JDSU, and Arrow Electronics. He holds a BSEET from the DeVry Institute of Technology (Chicago, IL); an MBA from Pepperdine University (Malibu, CA); an MDiv w/BL from Southwestern Baptist Theological Seminary (Fort Worth, TX); and a PhD from Southwestern Baptist Theological Seminary (Fort Worth, TX).