The missing link in ECU safety power supply

In the past, it was relatively easy to specify a power management approach for a given microcontroller and peripherals on an electronic control unit (ECU). However, as automotive system complexity grows exponentially, designers face many challenges. They now need devices that are intuitive, interchangeable, and able to facilitate platform development for power management and functional safety.

With the use of high computing performance MCUs and systems on chips (SOCs), the complexity of automotive systems continues to increase, providing some innovative applications and functions such as electrification, ADA, and regional/domain controllers. However, how to safely and efficiently power all different processors and system peripherals or high computing SOCs while achieving complex power-on and power-off sequences, simplifying board design, combining scalability, and reducing the risk of reliability failures caused by power hot spots. To answer these questions in the future, we need to analyze some key elements of the power management method.

Power management IC or discrete devices

Today, the fast pace of the automotive industry means that designs can be replicated across a range of vehicles, but with slight variations. The first choice to be replicated is the processor, followed by the power management aspects. A discrete approach offers power scalability and flexibility in layout and board layout, but as the solution becomes more complex, additional components such as sequencers, voltage monitoring and diagnostic needs are required. In addition, a small safety MCU and its software are required to manage the watchdog and system safety reactions. A solution based on a power management IC (PMIC) or system basis chip (SBC) will support this entire set of functions in one device without compromising scalability and ease of design.

SBC and PMIC for power platforms

To cope with the increasing complexity of automotive systems, designers decided to use SBC IC or PMIC. Due to the different systems, power needs to be transferred from the battery to multiple low-voltage domains. After switching to a distributed power architecture, many design limitations of the 12V/24V main battery power supply and the standard 5V automotive power rail are solved.

Under the distributed power architecture, high voltage SBC/PMIC (12/24V) and multiple low voltage PMICs (5V) can be combined and configured to meet multiple power needs. Additional power rails can be created by simply increasing the number of low voltage PMICs still powered by our high voltage SBC/PMIC.

Comprehensive functional safety

At NXP, we are very aware of the system safety requirements that hardware engineers must meet. Therefore, we developed the BYLink solution taking into account the reasons for higher safety integrity levels in smart safety mechanisms. Our portfolio consists of different pin- and software-compatible IC flavors that enable customer platform approaches and meet different safety requirements such as: QM/ASIL B and ASIL D. The adoption of a multi-PMIC system solution and thanks to the BYLink concept facilitates safety integration and eliminates all the obstacles that such complex safety systems may bring. While a single low-voltage PMIC can achieve QM or ASIL B levels, the entire power domain ECU can obtain ASIL D level through the main high-voltage PMIC, as it is responsible for monitoring critical voltages and the safety MCU and transitioning the system to a safe state in case of system failure.

Simultaneous sequencing

Another challenge of system complexity is the synchronization of the power-up and power-down sequences required to initialize different controllers and peripherals. A programmable power-up/power-down sequencer embedded in each device can be configured to fine-tune the sequence timing, ideal for flexibility and minimizing system BOM.

In a distributed architecture, how should devices be synchronized?

NXP's new BYLink concept helps ensure synchronization between all devices, avoiding any external additional components. With this cost-effective and reliable solution, the individual devices can be physically separated, reducing major heat points because thermal management is at the ECU level.

NXP’s scalable, expandable and secure BYLink system power platform is the solution

Enabling scalable power rails in a common IC footprint while sharing a familiar configuration interface for software portability between devices. These power management building blocks provide design flexibility and scalability by cascading system PMICs, essentially presenting as a single power solution. With the new BYLink platform, we are able to provide a simple yet essential link for secure and configurable power management designs.

To learn more about the BYLink platform, read the white paper.

author:

Jean-Philippe Meunier

Manager of Advanced Power Systems ADAS at NXP Semiconductors

Jean-Philippe joined NXP in 1999. With a Master's degree in Microelectronics, his career has focused on electronics and semiconductors for the automotive market, where he has held various positions including Product Engineering, Project Management, System and Safety Architect, and most recently System and Safety Solutions Manager. He is currently ADAS Segment Manager at NXP's Advanced Power Systems Division.