Design Of A High Efficient Multi-Mode Buck-Boost SMPS Controller IC

Since the fast development of power electronics technology, semi-conductor technology along with IC design and manufacture technology, portable devices are used more and more widely, which require better SMPS (Switch Mode Power Supply) ICs. The requirements include generating stable output voltage from a large input voltage range, operation with high efficiency in full load range, smaller volume and higher power density. In this dissertation, a SMPS controller IC based on 4-swtich Cascade BUCK_BOOST converter was designed to fulfill these requirements.After the analysis of variety of BUCK-BOOST topologies, a SMPS controller IC based on 4-swtich Cascade BUCK_BOOST converter was proposed, which provide different control strategy for different load conditions and different input voltages.(1) In heavy load condition: the system operated in PWM mode with voltage mode control. The system can switch in BUCK operation, BOOST operation and Transient operation according to different input voltages.(2) In light load condition: the system operated in BURST mode with hysteresis control. The system can switch in BUCK operation, BOOST operation and Improved BOOST operation according to different input voltages.The Transient operation and Improved BOOST operation were designed to minimize the switch power consumption compared with conventional method. The whole system architecture and control strategies improve the power efficiency on system level to reduce power comsumtion.Based on system design, the key modules of the system were analyzed and designed. For instance, the Muti-Mode Clock Generator with a PLL was fabricated and tested as a separate chip, the result show that the muti-mode function was successfully finalized and the noise performance was improved. This Muti-Mode Clock Generator can be used in power management ICs. The Erro Amplifier (EA) was designed taking into consideration of system loop compensation to guarantee the system stability. The Level Shifter, Current Sensing Circuit and Clock Generator was designed with some new structures to improve the power efficiency on circuit level. The whole system and circuits were designed in Candence EDA tool's SpectureS model supported by NSC 1.5μmBCD process. The simulation results show that the system operated properly and all the operation modes were realized and it can switch between different modes as designed. The design goal of this system, which is generating stable output voltage from a large input voltage range and operation with high efficiency in full load range, was successfully realized.