Analysis of hysteretic current mode switching supply without current detection

This paper presents a current sensor-less hysteretic current mode switching power supply. In a general, the switching power supplies are controlled in the voltage mode or the current mode. The current mode converters are used to the power supply system required of high reliability because it has high stability of the feedback loop compared to the voltage mode converter. The current mode converters are needed to detect the inductor current. The efficiency of the converter is decreased by the current detection resistor. In the proposed method, the inductor current is predicted by solving the equations from the circuit analysis. The converter is operated in a hysteretic current mode using predicted inductor current. Therefore, it is unnecessary to detect the inductor current. It is able to eliminate the current detection resistor. It is contribute to reduce the power loss of the main circuit. This prediction method can achieve the high prediction accuracy because it considers the some losses such as MOSFETs on-resistor, diode's voltage drop. This paper indicates the prediction error of the inductor current when the parameter of the circuit components includes the error. As a result, the proposed method is realized sufficiently high prediction accuracy for the inductor current.