CDM protection of high voltage LDMOS for automotive applications

In recent years, CDM compliance has been widely accepted as a critical part of product qualification to ensure product robustness. Hence technologies developed to support automotive market has increasingly required full AEC-Q100 ESD compliance to include a minimum of 500 V CDM robustness in addition to HBM and MM specifications. The high voltage devices developed to support 45 V to 80 V pins are typical requirements for automotive designs to support inductive loading from solenoid current which can generate dual polarity peak transients. The ESD protections designed for these pins need to be very compact high current device capable of clamping +65 V in forward mode coupled with -5 V in reverse mode. These ESD protections must also respond to transients of rise time (t_r) ranging from 10 ns to 100 ps to protect against HBM to CDM stress. This paper will present CDM design strategy to protect high voltage laterally diffused MOS (LDMOS) devices, requiring both primary and secondary ESD protection circuitry for 750 V CDM compliance.