Portable and Scalable High Power Analog Mixed Signal Circuit Design For Automotive Applications in BiCMOS Processes
Sri Navaneeth Easwaran, Texas Instruments, USA
The electronic content is increasing in automotive applications replacing earlier mechanical and hydraulics solutions. However proper protection and diagnostic circuits are required to ensure that electronic components perform the expected function and achieve ultimate fail silent operation. Topology wise, these automotive circuits are not much different from the conventional analog circuits used in consumer electronics, but have to handle a wide range input voltage from 5V to 40V and wide range of currents from 30mA to 4A. There are several additional system requirements and design implementation challenges that have to be considered when defining and implementing automotive safety circuits. This tutorial introduces the State of the Art requirements of automotive ICs.
The design of the ICs introduces the power stages and their driver along with challenges due to R-L-C type of loads with the design solutions is presented. Such designs need a good understanding of the junction temperature rise during the operation of power stages, and therefore an insight to thermal simulations will be presented. Test cases from high side driver, low side driver, configurable high side/low side floating drivers will be presented. These are used in several automotive applications for airbag, braking, power steering and solenoid drivers.
After discussing the power stages, the biasing circuitry for these power stages is covered. The power supply sequencing and various fault scenarios will be presented. A robust solution using the current and voltage selector based circuits will be discussed. Following the biasing circuits overview, the tutorial takes a deep look into the high voltage and negative voltage tolerant switches that are implemented for diagnostics in automotive applications.
Finally the tutorial presents the scalability and programmability of these designs. It does provide minor design tricks and recommended additional circuits that are needed while porting or redesigning the circuits from an older technology node to new one, like 0.35μM to 0.13μM.
Structures for the proof of concept are simulated and measured. Tutorial does cover the strong and thermally activated parasitic bipolar transistor that gets activated unintentionally due to the negative voltage requirements. The aggressor and victim concepts will be presented from test cases. Such unintentional activation can cause catastrophic fails to the system and the tutorial presents the design and layout based mitigation methodology to avoid the interference of these parasitic in any technology node. This tutorial will be valuable for the design community in general to carefully design high voltage fault tolerant circuits not only limited to automotive but also for industrial and personal electronics.
Dr. –Ing Sri Navaneeth Easwaran was born in Erode, India on October 19, 1977. After finishing his Higher Secondary school, he received his Bachelor of Engineering, B.E. Degree (cum laude) in Electronics and Communication Engineering from Shanmugha College of Engineering (affliated to Bharathidasan University, Tiruchirapalli, India), Thanjavur, India in 1998. He worked at SPIC Electronics, Chennai and STMicroelectronics, Noida, India between 1998 and 2000. From 2000 he worked for Philips Semiconductors at Bengaluru India, Zurich Switzerland and Nijmegen, The Netherlands where he designed analog circuits for Mobile Baseband and Power Management Units. While working at Philips Semiconductors, he also received the International M.Sc. degree in Electrical Engineering from the University of Twente, Enschede (Prof. Dr.ir. Bram Nauta’s ICD group), The Netherlands on the design of NMOS LDOs. From 2006 he started his work at Texas Instruments GmbH Freising, Germany and he joined the Technische Elektronik group at Friedrich-Alexander-Universität Erlangen Nürnberg in January 2010 as an external Ph.D student under the supervision of Prof. Dr. – Ing. Dr. -Ing. habil. Robert Weigel. His research focused on the fault tolerant design of smart power drivers and diagnostic circuits. He received his Dr.-Ing degree from Friedrich Alexander-Universität Erlangen-Nürnberg in May, 2017. Since September 2010 he is with Texas Instruments Inc, Dallas, Texas USA where he has the design lead for several airbag squib driver ICs. He has also designed analog high voltage, negative voltage tolerant circuits for automotive power steering and braking ICs. He was elected as the Senior Member of IEEE in 2011, Member Group Technical Staff at Texas Instruments in 2014. He has more than 15 patents (US and German) in the field of Analog Mixed Signal IC Design and has 6 IEEE and conference publications