Research On The System Compatibility Of DC-DC Switching Power Supply Integrated Circuits

Switching power integrated circuit becomes an important part of electronics devices, because of its advantages of high efficiency, high output current and so on. With fast development of the electronic technology, software and hardware performance, complexity and integrated level of electronic devices are continuous improved. Well system compatibility becomes the trend of development of DC-DC switching power supply ICs. The aim of this dissertation is improving the system compatibility of switching power integrated circuits. This dissertation focuses on research of key techniques and circuit structure of DC-DC switching power supply ICs. The techniques are implemented in DC-DC switching power supply ICs and verified by the whole chip design process and the test results. The mainly innovations and research achievements are as follows:(1) A loop reference voltage controlled soft-start circuit is presented. Circuit bases on digital to analog converter structure. Series binary resistors and unit ratio current bias are used to improve linearity. Novel switch structure is used to reduce the digital switching noise. Overcome the contradiction between soft-start time and integrated level. The proposed soft-start circuit has been implemented and verified in a 0.6μm CDMOS process high voltage buck DC-DC converter IC.(2) A switching frequency adjusted load transient response circuit is presented. The proposed circuit senses the output variation of error amplifier at load transient and controls the output switching frequency of voltage controlled oscillator to increase slew rate of inductor current. The circuit is realized by just few components and overcomes the defect of complex and low integrated of existing circuits. The proposed circuit has been implemented in a high voltage 0.6μm process high voltage buck DC-DC converter IC and verified by the post simulation results of the whole chip.(3) An open loop enable pin controlled switching frequency external synchronization circuit is presented. Only the delay circuits and the combinational logic compose the proposed circuit. The circuit detects the frequency range of external clock signal in enable pin and replaces the internal oscillator clock to synchronize the switching frequency directly and precisely without using phase locked loop. The circuit has simple structure and high synchronized precision. The problem of frequency jitter, low synchronization precision and low integrated level has been solved. The proposed circuit has been implemented and verified in a 0.6μm process high voltage buck DC-DC converter IC.(4) A switching frequency adaptive slope compensation circuit is presented. The constant current charged capacitor and the combinational logic are used to extract the switching frequency information. The circuit converts switching frequency into slope compensation current which realizes adaptive operation according to the switching frequency. The circuit avoids insufficient or excessive compensation in different switching frequency due to different inductor value. Both the stability and fast dynamic response is realized by the circuit. The proposed circuit has been implemented and verified in a 0.6μm process high voltage buck DC-DC converter IC.(5) A negative feedback loop controlled bootstrap driver circuit is presented. The circuit senses the bootstrap voltage and feeds it into a feedback loop structure which is used to regulate the bootstrap voltage and charge current precisely. Input supply of the DC-DC converter powered the proposed circuit increases bootstrap drive current and charge time of bootstrap voltage. Bootstrap voltage is not affected by switching node voltage at continuous current stage. The low bootstrap voltage precision and drive capability of existing bootstrap driver circuit with open loop structure is solved. The proposed circuit has been implemented and verified in a 0.6μm process high voltage buck DC-DC converter IC.