Streamlining Automotive Power Design in Safety Critical Systems

Introduction: 

Designing power systems for safety-critical automotive applications, such as electric power steering (EPS), braking, on board charger (OBC), transmission, and inverter, presents a formidable challenge for engineers. Modern vehicles are increasingly reliant on complex electronic systems that demand robust and reliable power management. These systems must operate flawlessly under harsh conditions, including extreme temperatures, vibration, and electromagnetic interference (EMI).

System designers are challenged with minimizing PCB space and component count, improving efficiency/thermal performance, differentiating the safety architecture, and reducing cost. The power management design must also remain compatible with the MCU of choice in addition to the various sensors and transceivers used in the application. While many MCU providers offer companion Power Management ICs, these solutions often ignore the critical challenges addressed above. The Allegro A81411 is a fully integrated power management IC (PMIC) meticulously designed to address these challenges, providing a comprehensive solution for safety-critical automotive systems that was developed to work with all the major automotive MCUs on the market.

How A81411 Addresses Design Challenges: 

Reduced Component Count and PCB Space: The fully integrated, buck-boost architecture with a single-inductor eliminates the need for multiple external components, such as a second inductor, a diode, and a FET, that are typically required in conventional boost + buck solutions (Figure 1). This integration dramatically shrinks the overall component count by 5 parts while cutting layout space by 2/3. 

Improved Efficiency and Thermal Performance: The buck-boost architecture delivers a marked improvement in efficiency, surpassing traditional boost + buck solutions by 5-15% across various operating conditions (Figure 2). Additionally, the lowered pre-regulator output voltage, 5.35V vs 5.8V, reduces the amount of voltage dropped across the LDOs. This enhanced efficiency translates to significantly lower power dissipation, reducing heat generation and improving thermal performance. Consequently, the A81411 can operate reliably at higher ambient temperatures, essential for under-the-hood automotive environments.

Enhanced Safety and Reliability: A81411 adheres to the rigorous ASIL-D safety standard, making it suitable for mission-critical automotive systems. It incorporates comprehensive safety and diagnostic features, such as fault detection and reporting. A crucial safety advantage of the A81411 is the higher absolute maximum voltage rating on its LDO input pins (40V vs 7V in typical solutions). This robust design protects the internal LDOs from damage in fault scenarios, such as a high-side FET short to battery voltage when in buck mode, ensuring system stability and preventing cascading failures (Figure 3).

Cost Savings: The A81411's integrated design and reduced component count contribute to substantial cost savings. The elimination of external components like inductors, diodes, and FETs reduces costs on average by $0.40-0.50 compared to typical solutions.

MCU Compatibility and Flexibility: A81411 is compatible and validated with leading automotive microcontrollers (MCUs), including but not limited to: Aurix TC2x, TC3x, TC4x, C2000, TMS570, MPC5xx, S32k3xx, RH850. 

Conclusion: 

This article explores the challenges of designing power systems for safety-critical automotive applications. As vehicle systems become increasingly complex, the demand for robust, reliable, and efficient power management is paramount. The Allegro A81411 PMIC addresses these challenges head-on with its innovative integrated buck-boost architecture. This single-inductor design significantly reduces component count and PCB space, leading to more compact and cost-effective systems. Furthermore, the A81411's enhanced efficiency and thermal performance ensure reliable operation even in demanding under-the-hood environments. Critically, for safety-critical systems, the A81411 is ASIL-D compliant and incorporates robust protection features, guaranteeing the highest levels of safety and stability. The A81411 is a game-changer for automotive power design, offering a streamlined, efficient, and highly reliable solution for the next generation of vehicles. 

For more information, download the A81411 datasheet, request a sample, or contact our sales team click here or visit the product page.