1 Introduction

LIDAR systems contain several critical components such as the laser arrays, time-of-flight sensors, and an MCU or processor. Monitoring the temperature of these components is essential for proper operation of the system. For example, LIDAR designs typically have two or more laser arrays and at temperatures above 70°C, the performance of each laser array will vary and require compensation. The time-of-flight sensor relies on optics, which has a different focus as temperatures change, making temperature monitoring crucial. Lastly, processors often become temperature sensitive around 105°C or higher. At high temperatures, designers may choose to lower the clock rate of the processor or shut it down to prevent overheating. Monitoring the temperatures of these components enhances safety and reliability and helps meet the ASIL requirements of LIDAR systems.

ASILs are established in ISO 26262 and specify the applicable requirements and safety measures needed to avoid unreasonable residual risk. The four ASIL levels range from A to D, with A representing the least stringent level and D the most stringent level. Depending on the specific function of the system within the vehicle, LIDAR systems can require up to an ASIL-D grade. Because temperature sensors used in these applications are often single-function devices, these safety standards are met using redundant and diverse temperature sensors. Redundancy means there are at least two temperature sensors where monitoring is needed, and the devices at each location may also connect to separate communication buses. Diversity ensures that the temperature sensors are as different as possible for safety reasons, and it can be introduced into the design in many ways (for example, differences in fabrication, packaging, die, common mode faults, and so forth). TI offers several options to achieve various levels of diversity depending on the requirements of the design.

There are different methods for meeting these temperature monitoring challenges, two of which are discussed in this application report. Option 1 is to use two thermistors or analog temperature sensor ICs at each location where temperature monitoring is needed. Option 2 is to use remote temperature sensors, which incorporate a local temperature sensor and remote channels for monitoring the temperature of another location. As is discussed, option 2 optimizes this design by using TI’s automotive remote temperature sensors to monitor several temperatures with high accuracy and fewer components.