Research And Design Of Dynamically Adjustable Drive Circuits For Digital Power System

Due to the rapid development of electronic products and the complexity of application scenarios,the design of chips needs to meet higher and higher requirements.The switching power supply,which is an important part of the chip,is also moving towards the direction of intelligence,miniaturization,and digitization.The analog switching power supply has a long development and the advantage of it is high reliability,fast transient and low cost.However,in the face of some complex application scenarios,such as the power supply adjust output voltage with the change of external signal,there is a large limit to the analog switching power supply.The digital switching power supply,due to its advanced control technology,can achieve new topology and output by replacing the firmware without changing the external components.At the same time,there are fewer peripheral devices for digital switching power supplies,which can save much area.The digital switching power supply also has the advantages of programming capability,support for PMBus protocol for ease of power system control,dynamic adjustment which can improve efficiency.At first,this paper introduces the types and components of digital switching power supply and analyses the conduction process of power MOSFET at length.Based on the above analysis,dynamic width control and adaptive dead-time techniques are proposed to dynamically adjust drive circuit and power MOSFET along with the change of load current.The segmented drive circuit is based on comprehensive consideration of the gate drive loss and the conduction loss of the power transistor for the optimized efficiency with the change of load current.The adaptive dead-time circuit also adjusts the dead-time following load current changes to reduce dead-time loss.Both of these technologies adjust the power MOSFET and drive circuit dynamically based on changes of load current.To ensure the normal operation of the chip,this paper designs current sense processor,thermal sense processor which protect chip from over-temperature and over-current.At last,crucial modules and output simulation is given to verify the design mentioned above.Based on the 0.35 um BCD process,using Cadence and Hspice to simulate the circuit and system.The simulation results shows that the chip has increase efficiency about 12% in the case of using dynamic width control and adaptive dead-time techniques which realize the dynamic adjustment of chip.The feasibility of the design and the correctness of the circuit are verified.