Driving the Future: Littelfuse Introduces 1300V A5A Trench IGBT

Littelfuse has unveiled its new line of 1300V A5A trench discrete IGBTs, engineered specifically for next-generation 800V battery electric vehicles (BEVs). These advanced semiconductors feature optimized collector-emitter saturation voltage (V_CE(sat)), robust short-circuit resilience, and broad current-handling capacity. They’re ideally suited for BEV subsystems where high surge current and low conduction losses matter more than switching frequency—such as PTC heaters, discharge circuits, and pre-charge systems.

A Shifting Industry: The Rise of 800V Architectures

Automotive electrification is gaining momentum, driven by sustainability goals and stringent emission regulations. Battery electric vehicles are at the forefront, with global sales of BEVs and PHEVs reaching 13.6 million units in 2023—a 31% increase from the previous year. Projections indicate this growth will only accelerate.

Yet, significant hurdles remain: high cost, long charging durations, and limited range continue to inhibit widespread adoption. To overcome these challenges, automakers are transitioning to 800V architectures. This high-voltage platform reduces current, accelerates charging, improves thermal efficiency, and lowers overall system cost.

Silicon Still Stands Strong

While wide bandgap (WBG) semiconductors like silicon carbide (SiC) have become the go-to for high-efficiency, high-frequency applications—particularly in traction inverters—silicon devices continue to hold strategic value. The maturity of silicon fabrication processes, lower costs, simpler gate drive requirements, and proven reliability make silicon-based IGBTs and MOSFETs viable alternatives for specific BEV functions.

In systems where switching frequency is low, such as PTC heating, pre-charge, and discharge circuits, conduction losses and thermal simplicity become more critical than switching speed. The larger die size of silicon devices facilitates easier heat dissipation, giving them a distinct advantage in these thermally constrained environments.

Application Spotlight: IGBT Use Cases in BEV Subsystems

Battery Disconnect Unit (BDU) Overview

Electric vehicles incorporate intricate circuit frameworks that segregate different functions. Among these is the Battery Disconnect Unit (BDU), which plays a central role in managing power flow and safety protocols. Three key subsystems within the BDU benefit from Littelfuse’s 1300V A5A trench IGBT technology:

1. Thermal Management: PTC Heaters

Unlike internal combustion engines, which produce ample waste heat, BEVs operate at significantly higher efficiencies and generate far less thermal byproduct. This necessitates active thermal management for two critical tasks:

• Regulating battery temperature

• Heating cabin space in cold climates

PTC (Positive Temperature Coefficient) heaters and heat pumps are leveraged to maintain battery performance and passenger comfort. The IGBT-based switching in PTC circuits typically operates at frequencies ranging from tens to hundreds of hertz. In these systems, low V_CE(sat), strong short-circuit withstand capability, and superior thermal performance are paramount.

2. Discharge Circuits

For safety, DC link capacitors in 800V BEV systems must be discharged in two scenarios:

• Controlled vehicle shutdown

• Emergency conditions (e.g., collision or critical fault detection)

These mechanisms, classified as ASIL-B under ISO 26262 standards, mitigate electrical hazards to occupants and service personnel while preventing fire risks.

The discharge event requires rapid voltage reduction of the DC bus to below 60V within 5 seconds. This is achieved by activating an IGBT switch, routing current through a discharge resistor (R_dis) to safely dissipate stored energy. High surge current capability and reliability under fault conditions make the A5A series an ideal fit.

3. Pre-Charge Circuits

To avoid inrush current damage, pre-charge circuits gradually energize the DC link capacitor during vehicle startup. These circuits typically include:

• Two high-voltage contactors (S1 and S2)

• A pre-charge switch (T1 – the IGBT)

• A DC link capacitor (C1)

The process begins with S1 and T1 closed, allowing controlled capacitor charging. Once voltage equilibrium is reached, T1 opens and S2 closes, completing the circuit without a surge. The IGBT’s surge resilience ensures reliable operation even under demanding startup conditions.

Littelfuse’s 1300V A5A Trench IGBT Portfolio

To meet the rigorous demands of 800V BEV subsystems, Littelfuse has developed a comprehensive portfolio of 1300V trench IGBTs. Designed for low conduction loss, enhanced thermal performance, and long-term durability, these devices represent the state-of-the-art in silicon power technology.

Key Features:

• Higher Breakdown Voltage (BV_CES):
  Rated at 1300V, these IGBTs offer extra margin above typical 800V battery voltages, ensuring reliability even during voltage surges due to state-of-charge variations.

• Expanded Current Range:
  From 15A to 85A at 110°C, these devices cater to a broad spectrum of applications—from passenger vehicles to commercial EV platforms.

• Low V_CE(sat) for Minimum E_cond:
  As one of the lowest V_CE(sat) devices in the 1300V class, A5A IGBTs significantly reduce conduction losses, easing thermal design constraints.

• 10µs Short Circuit Withstand Time (t_SC):
  This high fault tolerance ensures suitability for safety-critical automotive systems.

• Packaging Flexibility:
  Available in TO-263HV, TO-268HV, and through-hole TO-247 options. The SMD HV variants offer improved creepage and clearance versus standard 3-pin packages, enhancing insulation integrity in compact layouts.

Conclusion

As the electric vehicle industry transitions to higher voltage architectures, silicon-based IGBT technology continues to demonstrate its relevance in specific BEV domains. Littelfuse’s 1300V A5A trench IGBT family offers a compelling solution for applications where low switching frequency, low conduction loss, and high reliability are essential—such as PTC heaters, discharge systems, and pre-charge circuits.

By offering superior performance, enhanced safety characteristics, and versatile packaging, these IGBTs empower designers to balance cost, efficiency, and thermal constraints in the evolving landscape of 800V BEVs.