| A high-frequency high-efficiency current-mode monolithic Switching Regulator implemented with 0.5um BiCMOS process is analyzed in this paper. The chip has a wide input voltage range of 2.6V to 5.5V to generate adjustable output voltage range of 6V to 26V. A 1MHz oscillator circuit is imbedded and along with the function of soft-start, the chip also has protection functions such as UVLO, TSD and OVLO. The output current is adjustable simply by changing the outer sense resistor too meet customers'requirements. During circuit research, the basic principle of monolithic current-mode switching regulator is introduced at first. Then, the comparison between current-mode and voltage-mode is given in the thesis. With the comparison, we can understand the merits and drawbacks of these two topologies in order to use them freely. The author revised a new topology for this chip in terms of the customer's requirements and introduced several typical subblocks, such as shutdown, delay, current-sense, slope, sigma etc. Based on the principle analysis and circuit design in the beginning chapters, the author simulated all sub-circuits and the whole chip circuit using EDA tools HSPICE, the simulation result indicates that the IC has achieved the expectation, both function target and electrical characteristics. |
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