Research On Key Technologies Of High Performance On-Chip Power Management For Automotive LIDAR System

In order to achieve the vision of autonomous driving,automotive electronic system is becoming increasingly complex and intelligentizing,and new requirements to the functionality and performance of intergrated circuits are raised.As one of critical systems in autonomous driving technology set,automotive LIDAR(Light Detection And Ranging)brings new challenges to the power design,including various high performance powering demand,emerging 48V power bus,and high performance laser driver.To this end,this paper will focus on these requirements,investigating and developing several key power management techniques.To provide consistent high performance power supply for various point-of-load in LIDAR system,an enhanced current mode control is proposed.By involving adaptive quadratic slope compensation and anti-jittering ramp strategy,it provides optimal loop performance and attenuates jittering over various low voltage point of load requirments,and help reduce design complexity in system level.With enhanced current mode control,a general-purpose monolith high performance step-down converter isimplemented.The better overall performance than prior arts is verified by experiments.As for the high step-down ratio conversion,which is required by 12V/48V battery powered automotive LIDAR,an emulated current mode control with predictive over-current protection scheme is proposed.By engaging fast zero-Iq high voltage level shifter,smooth current sensing and ramp generator,35ns minimum on-time is achieved,thus converstion ratio can be increased with reliable over-current protection capability.Moverover,a VDMOS FET with lower on-resistance is introduced as low-side switch to improve conversion efficicency,which is co-pacakaged with control die to keep small size.Based on that,a compact fully integrated high step-down ratio buck converter is implemented and verified by experiments.Similar performance with prior arts is archieved with smaller solution size and better reliability.Aiming at small size,low cost,and high performance laser driver for automotive LIDAR,a pre-charge technique is introduced to walk around the most limitation of parasitic inductance.Hence 60W peak optical power can be realized within 2ns pulse width.By dedicated optimization,fast switching is realized with traditional LDMOS power device,which enable the cost-down through convtional BCD process fabrication.Based on these techniques,an integrated low cost high performance laser driver is implemented.The feasibility of this concept is well verified by experiments,and better performance can be achieved under same conditons.