Inductive current induction circuit for switching power supply

Abstract

The invention relates to an inductive current induction circuit for a switching power supply, which is provided with a switching tube circuit, an inductive current generating circuit and an inductive voltage generating circuit, wherein the output end of the switching tube circuit is connected with the inductive current generating circuit of which the output end is connected with the inductive voltage generating circuit; the output end of the inductive voltage generating circuit outputs inductive voltage; and the switching tube circuit, the inductive current generating circuit and the inductive voltage generating circuit are provided with the same common power supply input end and the same common input control signal. The inductive current induction circuit for the switching power supply utilizes the principle that a PMOS tube in a linear area is approximately equivalent to a resistance, adopts a self-bias current mirror, shortens the inductive current in proportion to induce the inductive current, converts the current and the voltage by a method that the inductive current flows through an output resistance, and generates stable inductive voltage.

Description

technical field [0001] The invention relates to a current sensing circuit, in particular to an inductor current sensing circuit for a switching power supply, which can accurately track the current in the inductor and output the induced voltage. Background technique [0002] Switching power supply circuits are generally divided into voltage mode control and current mode control. Current mode control has the advantages of fast dynamic response, simplified compensation circuit, and wide gain bandwidth, so it has been more and more widely used. In the current mode control circuit, the inductor current needs to be detected accurately and efficiently, so the inductor current detection circuit is particularly important in the current mode switching power supply circuit. [0003] The traditional inductor current sensing method usually connects a sense resistor in series on one side of the inductor ( figure 1 a) or directly use the on-resistance of the switch tube to detect the cha...

AI Technical Summary

Problems solved by technology

However, the method of series resistance produces additional power consumption, especially in the high-current switching power supply system, which greatly reduces the working efficiency of the system; in the method of directly using the on-resistance of the switch tube, the specific on-resistance of the switch tube The value is greatly affected by the process deviation, and there is a certain temperature coefficient, which makes the current sensing value not accurate enough. In addition, when the inductor current is small, a large on-resistance is needed to improve the accuracy of current detection, but a large on-resistance will inevitably cause Consumes a large amount of additional power consumption, which will greatly reduce work efficiency

Images