5 Isolation and Containment: Preventing Fault Propagation

In tightly integrated satellite systems, a local hardware failure on a single PCB can quickly affect neighboring subsystems—especially when high-voltage faults propagate through analog or digital I/O connections. This phenomenon, known as fault propagation, poses a serious risk to system integrity and mission success. To mitigate this risk, it is essential to introduce isolation barriers between critical circuit domains. These barriers contain faults locally, protect healthy subsystems, and allow graceful system degradation rather than total failure.

One of the most effective solutions for digital signal isolation in space applications is the ISOS141-SEP, a radiation-tolerant digital isolator from Texas Instruments. Unlike traditional optical isolators, the ISOS141-SEP uses capacitive isolation technology, which offers:

• Higher reliability in harsh environments
• Data rates up to 100 Mbps for fast and robust signal transfer
• Improved longevity and lower power consumption

This makes it ideally suited for high-speed communication between isolated circuit blocks, where both signal integrity and fault containment are mission-critical.

By implementing digital isolation with ISOS141-SEP, designers can significantly improve system-level robustness—ensuring that faults remain localized and that communication across the satellite remains operational, even under abnormal conditions.