Design Of Multi-channel And High-efficiency DC/DC Chip Based On Wearable Application

With the increasing market share of portable wearable devices,the demand for power management chips especially switching power chips has also grown rapidly.At the same time,because portable products are moving toward multi-functions,miniaturization,and low power consumption,the requirements for area and conversion efficiency of switching power supply chips are also increasing.As the functions of portable devices are increasingly diversified,the requirement of the whole SOC for the supply voltage is no longer limited to a single type.The traditional single inductor single output(SISO)DC/DC converter cannot meet the power supply requirement of the entire SOC due to the limited output number.Using several SISO DC/DC converters will increase the area of chips obviously and bring EMI problems.To solve this problem,in recent years many references have mentioned single-inductor multi-output(SIMO)DC/DC converters.This paper presents a single inductor double output(SIDO)DC-DC BUCK converter.By adopting double NMOS structure,converter conversion efficiency is improved.Firstly,this paper introduces the topological structure of the inductive switch power supply,taking the BUCK converter as an example to analyze the common control mode in the switching power supply,then on this basis analysing the working principle of SIDO and designing the structure and control strategy of the SIDO converter in this paper.Afterwards,the model of the SIDO converter loop and the design of compensation loop are designed in this paper.Then,the key circuit modules are discussed in detail such as OSC,the current sensing circuit,LEB and the bandgap reference.Besides,the control strategy adopted in this paper can reduce the cross-regulation problem of the ordered power-distributive control mode dual output converter to a certain extent.Finally,based on SMIC 0.18?m CMOS technology platform,the BUCK SIDO converter is verified by simulation in this paper.Simulation results show that the converter can start normally with a 3V input voltage and the converter has two different load conditions,in addition,the cross voltage regulation drops to 0.16 m V/m A and 0.147 m V/m A respectively by adapting cross regulation suppression structure.Meanwhile,when the load of both branches is 140 m A,the conversion efficiency of the converter reaches about 93%.The simulation results show that the SIDO DC/DC BUCK converter designed in this paper fulfils the design specifications,which is suitable for situations requiring low intermodulation and mutual interference.