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Powering Levels of Autonomy: a Quick Guide to DC/DCSolutions for SAE Autonomy Levels

Martin Moss1

TIConfident
ial–NDARe

strictions

Most of today’s automotive vehicles use some level of autonomy. The Society of Automotive Engineers (SAE)
defines five levels of autonomy, from level 0 to level 5 (Figure 1). In this technical article, I’ll discuss theDC/DC power-supply needs for each autonomy level. I hope that design engineers looking to understand thepower-supply challenges and requirements of automotive applications at various autonomy levels will find thisguide helpful.

Figure 1. Levels of driving automation (courtesy of SAE)
Levels 0 and 1

Rear view cameras are an ADAS feature often found in level 0 and 1 autonomy. Mostly powered directly fromthe car battery and sometimes tied to the rear light assembly, rearview cameras require small DC/DC converters
like the LMR34206-Q1 and LMR34215-Q1 with good noise reduction and low ripple. The sensor inside thecamera module is highly sensitive to noise from dark currents created by heat, but also to noise injected from or
through the power supply. A compact and low-noise low-dropout regulator (LDO) like the LP5907-Q1 can help
manage unwanted noise in the system.
Forward-facing camera systems, also present in level 1, use machine vision to identify objects and perceive theroad situation ahead of the car as the vehicle travels at higher speeds, requiring higher data-processing speeds
than rearview cameras and lower levels of latency. As such, these systems need more software and more power

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Powering Levels of Autonomy: a Quick Guide to DC/DC Solutions for SAE
Autonomy Levels
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for data processing, requiring high-efficiency converters like the LM62440-Q1 or LM61440-Q1 to help reduce
thermals and lower electromagnetic conduction.
Level 2
Level 2 involves partial automation and includes the control of two vehicle movements at the same time, forexample, steering and accelerating. Most high-end (and some mid-range) vehicles are at this level. As thenumber of sensors grows, so do the power needs.

ictions

Figure 2 shows a typical block diagram of a radar power management system, which comprises a small
electronic control unit (ECU) that needs a power supply with a low bill of materials, such as the LM63625-Q1,
and a second-stage power-management integrated circuit (PMIC) such as the LP87702-Q1. These device
families are scalable across various power levels for different radar types (such as corner, front, and side), andsince they have the same pinout and footprint, you can use them across a variety of designs.

strFigure 2. Typical power block diagram of a radar system

Re

Level 3–NDA

Level 3 involves conditional automation. The driver can now let go of the steering wheel, accelerator and brakes,
but some road conditions will need the driver to resume control. Level 3 increases the processing needs ofthe ECUs used in autonomous systems, as vehicles now have to integrate information from various sensors tomake decisions (a process called sensor fusion). As the power increases, a potential power component choice
for a forward-facing camera or cascaded radar could be the LM61460-Q1 buck converter, as it can support theincreased need for processing power.

Levels 4 and 5TIConfident
ialAutomakers use varying quantities and types of sensors to implement different levels of autonomy; this often
means that the processors need scalability in order to meet additional performance needs, and flexibility as
power requirements change. In such instances, you might not be able to support these power needs with asingle PMIC, and will require smaller and more flexible products. The TPS628501-Q1 and TPS628502-Q1 comein a small-outline transistor (SOT)-583 package, but have tight output tolerance and control loops to support
fast-acting transients for data processing and low latency.

Level 4 is called high automation; the car now works with features of full autonomy. Although the driver cantake control of the vehicle, the car is capable of performing various maneuvers without driver intervention. The
final level of autonomy, level 5, is defined as full autonomy, where the vehicle has full control and no conditions
exist where the driver (now essentially a passenger) can operate the vehicle. Levels 4 and 5 both require thehighest level of sensor data and incorporate LiDAR, which offers a 3D map of the environment and provides highquantities of data. Should lidar or radar fail for any reason, the vehicle will go into “limp home” mode and use
other sensors as backup.
For such high-power applications, consider the LM61495-Q1. This is one device in a highly integrated converterfamily which is pin compatible and supports 6 A to 10 A to supply the system requirements. For even higher
levels of power, a device like the LM5143-Q1 can support in excess of 20 A, and multiple phases, helping
support the power needs as well as canceling noise and reducing component count.

2Powering Levels of Autonomy: a Quick Guide to DC/DC Solutions for SAE
Autonomy Levels
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Conclusion
As the level of autonomy increases so does the power needs of the system, this will potentially mean new typesof power devices and architectures. Close consideration should be paid also to the system sensitivity to noise,
size, and cost.
Additional resources•TIConfidential–NDARe

strictions•

To learn more about evolving ADAS design requirements, read the white paper, “Paving the way to selfdriving cars with advanced driver assistance systems.”
Check out the white paper, “Making cars safer through technology innovation,” to learn how TI is innovating toensure safety and security of autonomous vehicles.

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IMPORTANT NOTICE AND DISCLAIMER
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCEDESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANYIMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRDPARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicablestandards, and any other safety, security, regulatory or other requirements.
These resources are subject to change without notice. TI grants you permission to use these resources only for development of an
application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license
is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you
will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of theseresources.
TI’s products are provided subject to TI’s Terms of Sale or other applicable terms available either on ti.com or provided in conjunction withsuch TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for
TI products.
TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2023, Texas Instruments Incorporated