Littelfuse, announced the AK-FL Series FlatSuppressX TVS Diodes. These axial-leaded transient voltage suppression diodes are designed to protect high-voltage DC aviation power systems from transient overvoltage events while providing a flat, low and stable clamping voltage.
Aviation and eVTOL platforms are adopting higher-voltage 270 V–800 V DC power architectures. This creates a design requirement for transient protection that limits clamping voltage tightly enough to prevent latch-up in solid-state power controller (SSPC) modules and other high-voltage semiconductor devices, without reducing surge robustness.
The AK-FL TVS diodes use Littelfuse proprietary FlatSuppressX technology, which employs an advanced foldback/snapback I-V characteristic to maintain a near-constant, low clamping voltage during fast transients and high-energy surge events. Unlike conventional TVS devices, which can exhibit higher and less predictable clamping voltages as surge current increases, FlatSuppressX devices control transient response while avoiding latch-up risk. This allows selection of lower voltage-rated semiconductors in high-voltage power circuits.
Charlie Cai, Director of Product Management for the Protection Business at Littelfuse, said: “The key advantage of FlatSuppressX technology is its ability to deliver a stable, low clamping voltage even under extremely high-energy surge conditions. For aviation applications, that means engineers can better protect SSPC modules and other sensitive semiconductor devices from latch-up, while meeting the reliability demands of DO-160 and MIL-STD-750 environments.”
The AK-FL Series is available in three current ratings: 6 kA, 8 kA and 10 kA at 8/20 µs. Each device is up-screened per MIL-STD-750 test methods. The series is the first FlatSuppressX TVS diode designed for aviation and eVTOL power protection and extends the FlatSuppressX platform beyond automotive systems into high-voltage avionics applications.
Key features include:
- FlatSuppressX technology with an advanced foldback I-V characteristic that maintains a flat, stable and low clamping voltage to help avoid latch-up risk in high-voltage circuits.
- Surge current ratings of 6 kA, 8 kA and 10 kA (8/20 µs).
- 100% screening per MIL-STD-750 methods, including vision inspection, surge test, temperature cycling and HTRB.
- Support for RTCA DO-160 avionics environmental qualification requirements.
- Ability to enable use of lower voltage-rated semiconductors in high-voltage power circuits.
The devices are optimized for protecting DC power rails and other circuits in high-voltage aviation power systems where sensitive semiconductor devices require precise clamping control. The axial-leaded package is halogen-free, RoHS-compliant and Pb-free E4 terminated, and supports both reflow and wave soldering.
Target applications include aerospace and defense 270 V–800 V DC aviation power trains, solid-state power controller circuits, eVTOL and next-generation aircraft electrical systems, and DC power rail protection in high-reliability avionics.
