Meeting ADAS Power Challenges

Cameras, sensors, complex algorithms, and microprocessors are teaming up to become a second pair of eyes for drivers, alerting them to road obstacles and blind spots, braking for them when necessary, and even helping them park their vehicles. These components are critical to enabling advanced driver assistance systems (ADAS) to help make our roads safer. In order for ADAS applications to function properly, they require power supplies that meet certain voltage accuracy, load transient, and fault protection requirements.

Balancing power demands and power constraints in ADAS applications is no easy task. On the one hand, these types of applications and their advanced algorithms are increasing the demand for onboard processing power. At the same time, power must be aligned with system performance goals. All of this occurs in a noisy environment consisting of multiple electronic subsystems.

Many automotive engineers choose to use multiple power rails to power each component in their ADAS modules, often with specific voltage regulation accuracy requirements. To meet stringent system requirements, they need precise, flexible and compact automotive power management solutions to address thermal constraints, electromagnetic interference (EMI) and heat dissipation.

Processors, memory, displays, and other vehicle subsystem components require well-regulated voltages at various current levels. To minimize heat dissipation, voltage regulators must operate efficiently to provide the power required to run these critical circuits. However, things get complicated when there are multiple power rails, so there are multiple voltage and current spikes to manage. Certain voltage rails have specific voltage accuracy requirements; if the voltage is out of specification, performance will suffer.

Another important consideration is the vehicle’s electrical and thermal environment. When a car starts up in various temperature situations (think cold start, hot start, or load dump scenarios), large and sudden voltage drops can occur. For example, consider a processor, which may be in standby mode at one point, consuming about one-third of its peak power. Then, when the processor is called into action, it can consume its full current. In this case, the output voltage of the switch-mode power supply will temporarily drop and then bounce back before settling to the target voltage. Effectively addressing these load transients requires a well-designed power converter to manage the output voltage swing.

EMI suppression is another priority, given the RF electrical noise from both internal and external sources. Automotive OEMs must ensure that electronic systems do not emit excessive EMI and are not affected by noise from other subsystems (CISPR 25 of the International Special Committee on Radio Interference provides standards for conducted and radiated emissions from vehicles.

There are multiple ways to address the challenges we have highlighted, from using discrete power solutions for each voltage rail to using higher capacitance components. Some approaches are more effective than others. There are also a variety of automotive-grade power management ICs (PMICs) designed to meet the performance and power requirements of ADAS applications.