Design Of Fast Transient Response LDO For Automotive Application

With the increasing demand for automobiles and the rapid rise in the proportion of electronic systems in automobiles,the automotive electronics market has been growing at a rapid rate.As a kind of power management chip,LDO(low dropout regulator)is widely used in various electronic systems,so the research of LDO for automotive applications has very important scientific research and market value.This article introduces the basic principles of LDO,and the difficult points such as high-precision bandgap reference,protection circuit,loop compensation and transient enhancement circuit in LDO for automotive applications are designed.Based on the analysis of the various error sources in the bandgap reference,for the voltage error related to high-order temperature,an exponential curvature compensation scheme based on Brokaw structure is proposed.Combined with the ?-help,the error caused by the base current is reduced.For the first-order temperature-related voltage error,a PTAT voltage trimming scheme is proposed to ensure static output accuracy while improving temperature stability.Corner and Monte Carlo simulation is designed to predict the temperature coefficient after PTAT voltage trimming.According to the application requirements of LDO,a high-precision bandgap reference circuit with high power supply rejection ratio is designed.The adaptively driven pre-regulated circuit improves the PSRR of the bandgap reference,the voltage and current trimming techniques improve the accuracy of the reference.The output of low-power trimming code generation circuit improves the accuracy of the reference output through voltage and current trim Technology.Aiming at the requirements of LDO for automotive application,a soft start circuit with slope enable control and slope reference establishment is designed to avoid inrush current during LDO startup.Over-temperature,over-current and under-voltage protection modules are designed for LDO.The circuit parameters were simulated at a temperature of-40?-150?and all corner of 6?,and Monte Carlo simulation of 6? was performed to ensure the stability of circuit performance a loop with pseudo ESR compensation and pole-pole tracking is designed.Combined with the structure of the LDO,a transient enhancement circuit is designed to improve the output accuracy of the LDO in the load transient response.This paper designs an LDO with fast transient response for automotive applications.The input voltage range is 2.7V-3.6V,the output voltage is 2.5V,the maximum output current is 200 mA,and the output capacitance is 1?F.During the transient response,the overshoot voltage is 17 mV and the settling time is 20?s;the overshoot voltage is 15 mV and the settling time is 5?s.