| With the development of electronics industry, DC/DC converters have been widely used in many electronic equipments. Now, peak-current-mode control strategy has become the primary control strategy in PWM DC/DC converters because of its good performance.In this paper, the basic theory of Peak-current-mode PWM DC/DC converter is studied. The stability of whole system is analyzed according to the system model,then the key modules and circuits which will affect the stability are designed and simulated with HSPICE.Error Amplifier is an important module in PWM DC/DC converters for the connection of its performance and stability of whole system. The Error Amplifier in this paper reaches the performance request with its wide bound of common-mode input, high output impedance, high open-loop gain and PSRR with 75dB, good phase-margin and response-speed. Slope compensation and Frequency compensation are needed in Peak-current-mode system with high stability. In Slope compensation module, use the rising-edge hiding technology to get more accurate current-sample and reduce the quantity of exterior components; also improve the structure of limit circuit to solve the problem that the loading ability decline. Adopting the equivalent capacitance multiplicative circuit, design an internal-compensation network to reduce the quantity of exterior components.The output ripple voltage of the PWM converter is±8 mV with the emblematical condition: 1.5V input voltage, 3.3V output voltage, 100mA loading current, 1MHz working frequency. It means that the whole system has high stability according with the design request. Moreover, the quantity of exterior components, cost and PCB area are all reduced for using various of internal-integrated technology. |
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