Adaptive Slope Compensation for Improving Load Capability

It is excessive or insufficient slope compensation current in buck DC-DC converters that cause available load current reduction and subharmonic oscillation issues. In this paper, a slope compensation circuit scheme was proposed, concerned with the input/output voltage changes and the product of the inductor current and the on-resistance of the power transistor. Compared with the traditional adaptive slope compensation circuit, the proposed circuit includes the influence factor of the power transistor on-resistance and demonstrates its slope compensation relationship, based on which an adaptive slope compensation circuit with Flip Voltage Fllower (FVF) structure is formed. Finally, the self-regulation and precise controlling of compensation amount can be achieved. The load capability and transient response of the DC-DC converter is improved and thus the system stability can be guaranteed. Experimental results show that the maximum inductor current change is less than 12% with the duty cycle ranging from 11% to 73%.