By Christopher Nunes
In a world increasingly driven by high-speed data, precision control, and robust connectivity, the humble transceiver plays a pivotal role. But not all transceivers are created equal. Enter the isolated transceiver—a quiet powerhouse that’s transforming how engineers design for safety, reliability, and performance.
So far in this blog series, we’ve talked about the importance of fault tolerance and wide common-mode range, for increased robustness in RS-485 and CAN communication. Now we are taking robustness to the next level by introducing the benefits of isolated transceivers but first let’s define galvanic isolation.
What is Galvanic Isolation?
Figure 1: Visual Representation of How Isolation Works in an Electronic Circuit
Galvanic isolation is a physical separation of two different ground planes but still allows communication to flow between each side. How is it done? Through magnetic and electric fields present in internal transformers and capacitors, electrical signals are transferred across the barrier. Analog Devices applied this isolation technology to a wide range of applications ranging from RS-485, CAN, I2C, to standard digital isolators, to isolated ADCs and much more.
Why You Need Isolation?
There are two different types of common isolation: functional isolation and safety isolation. Safety isolation provides protection against high voltages while functional isolation enables functionality within circuits. Depending on your application, your reason for needing an isolator may be due to either or both cases.
Human Safety
The easiest place to think about safety isolation is in the healthcare sector. Patient monitoring systems rely on isolated transceivers to protect patients connected to electrical devices against shock. An isolator will be placed between the high voltage systems and the systems connected to patients to keep them safe from 5000 Vrms or greater transients.
Circuit Function Protection
An example of functional isolation can be found in battery management systems (BMS), where the circuitry can be referenced anywhere from a few volts to a few hundred volts from the controller. Isolation is necessary for the system to work because the low voltage components need to communicate control commands to the high voltage systems that have working voltages a few hundred volts apart.
The industrial sector is an area where both functional and safety isolation is necessary, where isolation provides safety for the operators in the factory, but also protects communication between the low voltage controllers and high voltage systems such as motors.
Ground Reference Separation Benefits
Isolation also aids field bus transceivers by preventing ground loops. Ground loops appear when there are multiple paths to different ground references (like in RS-485 where the devices can be up to 4000 feet apart), but those references are not electrically identical causing voltage imbalances between the references. The voltage differences can cause a potentially large current to flow between the two ground planes, which can exceed the transceiver’s absolute maximum ratings and harm the transceiver or cause communication errors from going out of specification. An isolated transceiver allows the bus side’s reference to float relative to the local Earth ground on the logic side, preventing the voltage imbalance that stops the ground currents from forming.
Figure 2: EVAL-ADM2896E Evaluation Board
Figure 2 showcases the ADM2895E, which is an RS-485 transceiver that has ±60 V of fault protection and ±25 V of common-mode range, but also has the ability to isolate up to 5700 Vrms across the barrier for ultra robust applications.
Let’s consider another scenario where improving signal integrity is key. If there is a problem with a noisy reference plane interfering with sensitive components, the physically separate planes can isolate a noisy reference to give the sensitive equipment a silent ground plane to operate properly.
Conclusion
When it comes to building systems that last, galvanic isolation is the secret sauce to keeping your systems safe and functional. It keeps signals clean, protects people and equipment, and makes sure everything stays connected—even when voltages are mismatched. Whether you're working with motors, medical devices, or battery packs, isolation helps your design withstand the punches with confidence.
See the blogs in the TranscendingConventionalFieldBus series.