Design Of Full-bridge Motor Drive Chip With Integrated Current Limiting Function

The acceleration of the electrification process has made the application prospect of the motor system more extensive,but the electric power consumption of the motor system has always accounted for more than 60% of the total power consumption,which is one of the major difficulties to be overcome for energy saving and emission reduction.With the continuous development of the BCD process and smart power integrated circuit(SPIC)to provide excellent conditions for design,coupled with the expansion of market demand and the promotion of green environmental protection concepts,the motor driver chip is the core part of the motor system,and its diversified development And optimization is imperative.This article deeply studies the development status and development trend of motor drive chips at home and abroad.Based on this,a full-bridge motor drive chip is designed based on a company's 0.18?m BCD process,which integrates current limiting and rectification functions.It can work in-40 ? 150 ? environment,working power supply voltage 8-40 V,peak output current ± 3.5V.Two input terminals are provided to realize motor speed and bidirectional control through external input pulse width modulation(PWM).The maximum current of the chip can be adjusted by the external input reference voltage and current detection resistor,and the maximum output current is preset at a known level,which effectively limits the opening current and the stall current.The current decay mode is used to reduce the power consumption of the system,and a stable voltage can be maintained without a large capacitor.Over-temperature protection uses digital control to improve system reliability.The chip uses four N-channel LDMOS to form an H-bridge and integrates power supply circuit,logic control circuit,drive circuit,and various protection circuit modules.It is suitable for DC motor system.The article first gives an overview of the working principle of the full bridge,and details the rectification mode of the full bridge and three current attenuation modes of fast attenuation,slow attenuation and mixed attenuation.With this as the theoretical basis,the design framework of the chip is constructed and the chip's parameter index is determined to complete the design and analysis of the core module.The bandgapreference and NMOS-LDO provide a stable supply voltage for the chip.The charge pump provides the voltage for the high-end drive.Based on the rectification theory,the maximum current control circuit and the hybrid attenuation control circuit are proposed to reduce the loss during the PWM operation.The driving circuit realizes the charging and discharging efficiency of the full-bridge MOSFET gate capacitance.Propose over-temperature,over-voltage and under-voltage protection circuits with hysteresis to ensure the reliability of the system.And the function and performance simulation of each sub-circuit.Finally,the whole circuit is built according to the design framework,and three current attenuation modes are simulated and verified respectively.The simulation results show that the motor driver chip originally designed basically meets the design specifications.