As avionics and defense systems continue to push toward higher power densities and more compact designs, protecting sensitive electronics from high-energy transient events is becoming more complex. Lightning-induced surges, in particular, remain one of the most demanding threats—requiring protection components that can handle extreme energy levels without compromising size, weight, or manufacturability.
To address this, Littelfuse has expanded its high-reliability transient voltage suppression portfolio with the SM15KPA-HR/HRA and SM30KPA-HR/HRA TVS diode series. These devices are designed specifically for mission-critical environments where both electrical performance and system-level reliability are non-negotiable.
Designing for Lightning-Level Threats
Aircraft electronics must operate in environments where lightning strikes and induced surges are not rare edge cases—they are expected conditions. Standards like RTCA/DO-160 define strict requirements for survivability, with Waveform 5A Level 5 representing one of the most severe transient conditions.
The new TVS diode series is engineered to meet these demands directly. With peak pulse power dissipation ratings of 15 kW and 30 kW (10/1000 μs), these devices are capable of absorbing significant transient energy while maintaining stable clamping performance. Fast response times—less than 1 picosecond—help ensure that sensitive downstream components are protected before voltage spikes can propagate through the system.
Moving High-Power Protection into SMT
One of the more meaningful shifts in this release is the move away from traditional axial-leaded packages toward a surface-mount form factor. Built in a compact SPD4-1 package, these devices support standard SMT pick-and-place assembly, aligning with modern electronics manufacturing workflows.
This transition addresses several long-standing challenges in aerospace electronics:
- Reduction in board space and overall system weight
- Elimination of through-hole assembly constraints
- Improved manufacturability and consistency in high-volume or complex builds
For applications like flight control systems or compact eVTOL platforms, these advantages directly translate into more efficient system integration.
Electrical Performance and Reliability Screening
Beyond power handling, the series is designed to deliver consistent electrical behavior under stress. Key performance characteristics include strong clamping capability, low incremental surge resistance, and stable operation across a wide junction temperature range from –55°C to 150°C.
Reliability is reinforced through extensive screening aligned with MIL-STD-750. Devices undergo 100% surge testing, temperature cycling, high-temperature reverse bias (HTRB), X-ray inspection, and final electrical characterization. For applications requiring even tighter assurance, the HRA variants include additional Group B testing, providing extended confidence margins for aerospace and defense qualification.
Flexibility Across System Designs
The series is offered in both unidirectional and bidirectional configurations, allowing engineers to tailor protection strategies based on the specific characteristics of the circuit. Whether protecting DC power rails, data lines, or mixed-signal interfaces, this flexibility simplifies design decisions across a range of architectures.
In addition to lightning protection, the devices also provide up to 30 kV electrostatic discharge protection in accordance with IEC 61000-4-2, further extending their usefulness in electrically noisy environments.
Target Applications
These high-reliability TVS diodes are aimed at systems where failure is not an option and transient exposure is unavoidable. Key use cases include:
- Avionics flight computers and control systems
- Navigation, communication, and radar electronics
- eVTOL propulsion and battery management systems
- Aerospace and defense power distribution modules
- High-reliability industrial and transportation platforms
A Practical Shift in Protection Design
The introduction of high-power TVS diodes in a surface-mount format reflects a broader shift in how protection is being integrated into modern electronic systems. Designers are no longer forced to trade off between performance and manufacturability. Instead, components like these enable both—delivering the energy-handling capability required for harsh environments while fitting into streamlined, automated production processes.
As power levels increase and systems become more compact, this combination of performance, reliability, and integration flexibility will play a larger role in how next-generation avionics and mission-critical platforms are designed.
