Average current control circuit and average current control method

Abstract

The invention discloses an average current control circuit and an average current control method. In the circuit, one input terminal of an average current detection module is connected to a reference voltage signal output terminal of a band gap reference source, and another input terminal is connected to a source terminal of a power switch. A voltage transmission signal output terminal of the average current detection module is connected to an input terminal of a current regulator. Another input terminal of the current regulator is connected to the reference voltage signal output terminal of the band gap reference source, and an output terminal is connected to a negative input terminal of a comparator. An oblique wave generator input terminal is connected to the source terminal of the power switch, and an output terminal is connected to a positive input terminal of the comparator. An input terminal of a logic and driving circuit is connected to an output terminal of the comparator, another input terminal is connected to a switch starting pulse output terminal of an oscillator and an output terminal is connected to a grid terminal of the power switch. The source terminal of the power switch is connected to a grounding terminal via a detection resistor and a drain electrode is connected to a switch power supply module. Constant current precision is high, a current ripple wave is small and anti-noise performance is superior.

Description

technical field [0001] The invention belongs to the technical field of microelectronics and power management, and in particular relates to an average current control circuit and an average current conversion method. Background technique [0002] The average current control circuit is a common control scheme for constant current power supplies, and has important applications in energy-saving lighting circuits, screen backlights, high-power lighting and other fields. Compared with the peak current control circuit and the hysteresis current control circuit, the average current control mode circuit has the advantages of high control precision, small current ripple, and excellent anti-noise performance. However, limited by the control principle, the circuit structure is often complicated, the design is difficult, and the response speed is slow. [0003] Common average current control circuits need to directly detect the current flowing through the inductor, so the sampling resis...

AI Technical Summary

Problems solved by technology

However, limited by the control principle, the circuit structure is often complicated, the design is difficult, and the response speed is slow.

[0003] Common average current control circuits need to directly detect the current flowing through the inductor, so the sampling resistor must be connected in series with the inductor to detect the change of the voltage signal at both ends of the resistor. For step-down switching power supplies, no matter what topology is used, this Either end of the detection resistor will not be the actual ground, so if you want to detect the voltage change at both ends of the resistor, you can only reset a chip ground, which will put higher design requirements on other parts of the control circuit, or you need to detect the resistance at the same time. The voltage across the resistor, but this is not suitable for high-voltage application circuits, even for low-voltage circuits, a more complex current detection module is required to convert the voltage across the resistor into a current

Due to the complexity of current detection, the application of the average current control circuit is severely limited, and the design complexity of the circuit is also increased, which occupies a large chip area and increases power consumption.

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