Research On The Modules Of Current Mode Switching Power Supply Controll IC

Switching power supply (SPS) is the most efficiency and costless power supply. It is representing the developing trend of regulated power supply and widely used in various electronics and electron devices. With high integration, high performance-cost-ratio, elegant peripheral circuits, and many other advantages, monolithic SPS has becoming the best choice to develop middle and small power SPS. The core of the monolithic SPS is the control IC which determining the performance, cost, reliability and stability of SPS products, and focused on by many researchers with various functions built in it recently.The dissertation focuses on the control IC of fly-back SPS. By adopting control methodologies such as PWM, PFM and PSM, a control IC with many features such as high performance cost ratio, low cost, complete protection, excellent anti-EMI and free audio noise is presented.Bipolar and CMOS technology are used respectively to discuss system simulation and design and circuits implements of SPS control IC. In bipolar section, co-simulation of all modules has been done, and working situation such as start-up, over and lack voltage, green-mode, current limitation is also been simulated and verified. Periphery circuits and frequency compensation network is designed and simulated using SPECTRE, finally, a 5V output with only 20mv ripple is obtained. Meanwhile, 1.5μploy emitter technology is used to achieve IC layout and the layout has been verified after writing verification command file.In CMOS section, a current mode SPS control IC system with multiple functions and complete protection is presented. Utilizing Charter 0.35μCMOS technology, main function modules of band gap reference, oscillator, frequency jitter, LEB and so on are designed and verified using simulator SPECTRE, and the band-gap reference has been taped out.