Application of TCAN4550 and TPS3702 in EV/HEV functional safety system

alan000345 · Published on 2018-10-22 10:15

Application of TCAN4550 and TPS3702 in EV/HEV functional safety system [Copy link]

Hello everyone, with the development of these years, more and more automotive-grade applications have added the concept of functional safety level requirements. Under this development trend, more and more processors with functional safety features and peripheral system designs will be focused on. Generally speaking, in the design of on-board chargers, DCDC converters, and automotive traction drives, for customers who already have ready-made solutions, how to add some functional safety designs to the system so that the entire system can reach ASIL-B or ASIL-C or even ASIL-D is often the focus of everyone's attention. The Hercules series functional safety processor TMS570 currently promoted by TI can reach the functional safety level of ASIL-D. It is a set of solutions that add functional safety design while maintaining the original design architecture. However, with the development of vehicle-mounted systems, the demand for CAN-FD has been continuously proposed, which makes some design solutions without CAN-FD built-in controllers face great shortcomings. This article will focus on [color=rgb(170, 102, The TCAN4550-Q1 solution can be used to add CAN-FD functionality to controllers without CAN-FD controllers, or to add an extra CAN-FD communication channel when the number of CAN-FD interfaces is insufficient. The TCAN4550-Q1 solution is a SPI to CAN-FD controller with built-in CAN-FD PHY. It has passed the AEC Q100 certification, built-in watchdog, and +/- 42V BUS Fault Protection. It supports ISO 11898-1_2015 and Bosch M-CAN Revision 3.2.1.1, and can meet the requirements of ISO 11898-2_2016. The maximum rate can reach 5Mbps, and the SPI clock frequency can reach up to 20MHz. The sleep wake-up of TCAN4550-Q1 supports remote wake-up mode, which can be achieved by sending ISO Wake Up Pattern (WUP) on the CAN bus.

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Introduced here, I believe everyone has a good understanding of [color=rgb(170, 102, The functions of TCAN4550-Q1[/url] are roughly understood. The communication on the CPU side is SPI, and the external data is the CAN-FD interface. The next question that everyone may be more concerned about is how to design the system in a functional safety system to ensure its functional safety characteristics and achieve a certain ASIL level.

In the system using TCAN4550-Q1, we can abstract the following topology, Node 1 is our current system design. In this system, we need to pay attention to three parts:

Host MCU: This part is generally a functional safety processor, such as TMS570, etc. Generally, it has functional safety level certification from the device level, and can provide relevant functional safety manuals, etc. to confirm that the system designed using it can achieve the functional safety level target.
TCAN4550-Q1: That is, the CAN-FD communication part. TI is about to release the certification of this part and related functional safety manual materials to confirm that it can achieve the corresponding functional safety level in the system.
SPI communication: This part is more about authenticating the integrity of its data from the perspective of system communication, and there is no difference from the system design of general SPI communication devices. Simple redundant transmission can be used, and then data comparison is performed on the MCU side to confirm its data integrity.

The pain points we see at present, in addition to the support of CAN-FD, there is another problem, that is, for the existing C2000 or the system that hopes to use an independent power supply solution, how to deal with the unstable power supply and prevent the abnormal behavior of the CPU. At present, TPS3702 series voltage monitoring products can effectively check the unstable situation of CPU power supply, and it is also very simple to use.

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[color=rgb(170, 102, TPS3702 can detect overvoltage and undervoltage in time and provide feedback to LDO/DCDC or the corresponding processor side. 102)]查看详情

In a multi-channel voltage monitoring scenario, multiple TPS3702 may be required. It should be noted that TPS3702 has different suffix part numbers for different voltage detection. For details, please refer to Datasheet of TPS3702:

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In addition, for the design of C2000, the following TI-Design provides a very good reference:

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Monitoring Voltage Rails on Delfino with TPS3702 Reference Design

Finally, for the TPS3702 series of voltage monitoring products, in addition to a variety of monitoring voltage levels, there are also more choices in terms of function selection. For example, TPS3702 series of voltage monitoring products.The TPS3850 is a single-channel voltage monitor with a window watch dog function. The dual-channel voltage monitors include the TPS3086/7; the three-channel TPS3306/7; the four-channel TPS386xxx; and there are also separate overvoltage/undervoltage monitoring products. For more choices, you can search on www.ti.com, or go to the https://e2echina.ti.com/ technical forum to post a question.