Design And Verification Of A Switching Mode Power Supply Converter With Fast-transient-response Characteristic

With the rapid development of integrated circuit technology,power management chips for portable device applications with its high integration,high efficiency and high control accuracy in the semiconductor field have seen a meteoric rise.At the same time,lightweight,ultra long running time and stable power supply makes the power management chip market become a focus in the electronics field.What's more,with the wide application of portable devices,higher requirements for power management chips are also presented,such as low cost,low power consumption,high reliability and so on.Therefore,in accordance with market demands,the development of power management chips with more powerful performance has been an idea of research and development engineers.This paper studies the working principle of DC-DC switching power supply,focuses on the systematic and comprehensive analysis on BUCK DC-DC and designs a chip with the pseudo PWM,PFM modulation system and continuous and non-continuous inductor current working mode through comparing the advantages and disadvantages of topology,modulation system and working mode.The main work and innovations of this dissertation are as follows.A constant-on-time control is employed to provide transient response through the sampling output voltage on the upper power MOS to open the action,so that the adjustment time is shortened.At the same time the circuit loop does not contain the error amplifier,so no need to consider the issue of compensation.In order to improve the detection speed of inductor current,this paper presents an approximate lossless current sampling circuit.At the same time,the fast response of the discontinuous conduction mode DCM can be easily achieved by changing the ratio of the input resistance to make the output voltage of the sampling circuit truly reflect the change trend of the inductor current.In addition,on the basis of the traditional sampling structure,the burrs on the power supply voltage can be effectively suppressed by the series capacitance between the gate and the source of the regulating tube.In order to provide a constant switching frequency in a variety of input voltage range,this paper creatively introduces the design of out of chip resistor to counteract the frequency change caused by the change of input voltage.The circuit uses synchronous rectification technology,with the current continuous conduction and non-continuous conduction current of two different work modes,a series of chipintegrated circuit protection,so as to avoid the problem of over-voltage,short circuit,over temperature and current.The circuit uses synchronous rectification technology,has two different working modes of the current continuous conduction and current discontinuous conduction and integrates a series of protection circuit,so as to avoid the problem of over-voltage,short circuit,over temperature and over current.The circuit is implemented in 0.5?m BCD 18 V process,simulated and verified by Cadence EDA design tools and Spectre simulation platform for its key sub-block and the overall circuit.After verification,in the same based on constant on-time control mode,when the load from the 0.5A to 3A,the transient response of the basic synchronization to the load current jump time,low voltage at the same time due to undershoot;in the inductor current detection circuit design,common gate amplifier has been working in the normal state,the a cycle when the switch tube is opened when the system does not require time-consuming to restore the working state of each tube.Thus,when the inductor current begins to rise from zero,the output CS can change the inductor current response quickly,so as to improve the working efficiency of the whole system;the effective range of the input voltage,the switching frequency is almost not changed with the input.