TI Automotive Safety and Intelligence 2024: Radar edge architecture gives way, satellite architecture is coming

The new year has begun, and the 2024 CES exhibition is also busy with the launch of new products. The editor followed the engineers of Texas Instruments to explore the new automotive chips unveiled at the 2024 TI CES exhibition: the radar sensor AWR2544 optimized for satellite architecture, the programmable drivers DRV3946-Q1 and DRV3901-Q1 that improve the safety of electric vehicle battery disconnection , and see how they help build smarter and safer cars.


What is the satellite architecture and its advantages?
If you want to achieve 360° panoramic imaging of the car through the car millimeter wave radar, you need to place radar sensors at different positions outside the car like arranging satellites, as shown in the figure below. If the edge computing architecture is adopted, what is needed is that each radar sensor will fully process its own data and then give a result to the central processor. Unlike the edge architecture (a single radar sensor performs all data processing independently), the data processing part of the satellite architecture is not completely completed by the edge sensor, but will be coordinated and handed over to the central processor for judgment. Through data fusion, the judgment accuracy will be higher, which can improve the accuracy of ADAS, making the car smarter and safer. In addition,

under the satellite radar architecture, it is easier for automakers to use wireless software updates to improve system performance and enhance safety.

Image: Radar sensor connected to a central ECU in a satellite architecture

What optimizations have been made to the AWR2544 designed for satellite architecture?
From the following comparison chart of the functions of AWR2944 and AWR2544, we can clearly see that the AWR2544 optimized for satellite architecture lacks the DSP part compared to the AWR2944. That is, as we said before, the data processing of the new generation of radar sensors is not completed independently. It does not need to output the entire radar signal processing result, but it does not hand over the most original signal to the central processor. Let’s also talk about AWR2944 here. Although it was released earlier than AWR2544, they are both TI’s second-generation radar products, and the RF performance of both is 50% higher than the first generation. In addition, let’s learn about the naming rules of TI radar sensor models. The second number represents the complexity of the processor inside the chip. The larger the number, the stronger the processing power. Therefore, the chip processing power of AWR2944 is actually stronger than that of AWR2544. It is a single-chip radar, which means that all radar signal processing is completed on one chip.



Figure: Functional block diagram of AWR2944

Figure: AWR2544 functional block diagram


Designed for satellite architecture, the AWR2544 is a chip with partial processing capabilities, not a radar with a traditional single-chip output interface. In addition to an integrated 77GHz transceiver with four transmitters and four receivers, it provides greater distance detection and better performance, and also includes a cost-optimized radar processing accelerator and a throughput-enhanced 1Gbps Ethernet interface for generating and streaming distance FFT compressed data. The device meets automotive safety integrity level B and can provide a secure execution environment through a hardware security module.


A brief discussion on the AWR2544 process and packaging
AWR2544 uses a 45nm process. Will this lag behind the existing 28nm process radars on the market? In this regard, Chris Meng, a senior field application engineer at Texas Instruments, said: TI has a dedicated process department and has its own research and development on the process. The radar chip is specially optimized on the basis of 45nm, making the RF performance higher, allowing users to achieve the performance of lower nanometer-level chips on the 45nm process, as well as better cost performance. TI's 45nm is more than 45nm.

AWR2544 uses waveguide interface packaging (LOP, Launch-on-Package) technology. The main benefit of using this package is that the size of the radar sensor is reduced by 30%, the RF performance is improved, and the detectable distance is extended to more than 200m. This technology can transmit the signal from the packaged radiating element directly to the 3D antenna through the waveguide in the printed circuit board (PCB). The figure below shows the AWR2544LOP evaluation module with a 3D waveguide antenna.






LOP is not a new technology. When customers used the AWR2243 chip design, the PCB board was connected to the waveguide chip through the detour. This time, the new product TI directly uses LOP packaging, which will make the antenna signal-to-noise ratio better. At the same time, it can save PCB costs compared to using ordinary antennas. There is no need to use expensive RF PCB materials. The PCB board can be made smaller and there is no need to use some microvias. Another feature is that it has a certain degree of flexibility. Generally, once an antenna is made, its FOV and gain are fixed. If you want to change it, you have to redesign the PCB. However, if you use LOP technology, the PCB does not need to be changed. You only need to replace the waveguide antenna below to achieve different antenna FOVs and gains.



New driver products that improve the safety and efficiency of HEV/EV battery disconnection systems
The battery management system (BMS) of electric vehicles, medium and high voltage relays and circuit breaker fuses are indispensable components in the power distribution part. The demand for higher voltage, current, efficiency and reliability is growing. In response to this demand, TT has launched two new programmable integrated drivers in 2024. The so-called programmable means that its drive current and time can be adjusted through the SPI interface. One is the integrated contactor driver (Contactor Driver) DRV3946-Q1, and the other is the pyrofuse driver (Pyrofuse Driver) DRV3901-Q1 that can realize the state system of the intelligent thermal fuse. Both meet the functional safety standards of ISO26262.

Figure: Battery disconnect fuse and high-voltage relay in BMW power distribution


Regarding the integrated contactor system driver DRV3946-Q1, it can be used to drive two solenoids in automotive applications. It integrates a peak holding current controller, the peak current allows it to quickly pull the relay, and the instantaneous pull can improve system safety; it integrates a holding current controller, which can maintain the pull-in state with a small current after the system is pulled in, saving system power consumption. In addition, it can improve system efficiency through integrated peak holding current and low-ohm power control stage. That is to say, its built-in impedance is very low, and the power consumption of the chip itself will be very low. First, its own heat will be reduced, reducing the complexity of system design. Second, it will also reduce the overall battery power consumption of the system. Third, it is extensive. This solution can not only be used for solenoid type current control, but also can use various different Contactor Drivers to drive various types of relays and switches.

Figure: Simplified schematic diagram

of DRV3946-Q1 Regarding the integrated squib driver DRV3901-Q1, it is a highly integrated squib driver designed for electric vehicle thermal fuse applications. Compared with the discrete solutions built with multiple chips on the market, it can naturally reduce system complexity and improve efficiency. It includes the power supply, current detection and regulation, and diagnostic and protection functions required to drive the squib load. Compared with traditional squib drivers, it also has a hardware pin trigger interface, energy storage capacitor diagnosis, addressable SPI, and an optimized driver stage with integrated charge pump and additional deployment current options.

Figure: Simplified schematic of DRV3901-Q1

There is a lot to look forward to in the future of automobiles, and many chip products will emerge as a result. We look forward to the automotive track in 2024, which will be full of excitement.