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In recent years, the portable electronic products such as mobile phones, is becoming more popular in the market. So efficient power management becomes a key factor in electronic design, Pulse Width Modulate (PWM) DC-DC switching converter is characterized as high efficiency, and is very suitable in battery-operated portable electronic devices.First it has been done to study the main topologic structure of power management, and analyze and compare the switching converters with different topologic structures or control modes, then decide to adopt the current switching converter with PWM control mode.Then further study of the main principle of buck current DC-DC converter with PWM control mode has been done. The DC-DC converter has three features: current mode control, PWM, synchronous rectification technology. This paper makes the analysis of the principles of the features.Every sub-circuit is designed reasonably according to the principle and character of PWM switching converter, such as: bandgap, error amplifier (EA), oscillator, PWM comparator, current sense, PWM flip-latch, fault logic with soft start, dead time control and so on. It is analyzed in detail that how to realize every sub-circuits’functions according to different needs, then the sub-circuit was simulated with Spectre emulator of Cadence, and the simulated curve is given. At last, the simulation results of the system, which can show that the circuit is correct, are given.
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