Constant current circuit and constant current controller

Abstract

The invention relates to a constant current controller. The constant current controller is used for generating a control signal for controlling a peripheral circuit which comprises an inductor to generate a constant current signal; the constant current controller is integrated with a power tube and a power supply circuit; when standard timing is jointly generated according to an over voltage protection signal supplied by an over voltage protection pin and a reference voltage supplied by a floating voltage source, the power tube detects inductor demagnetizing time; and when the inductor demagnetizing time is less than the standard timing, over voltage protection is triggered. The invention also relates to a constant current circuit comprising the constant current controller. By virtue of the constant current circuit and the constant current controller, the standard timing in a chip is not influenced by a reuse pin any more, so that high-precision and programmable output over voltage protection can be realized consequently.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a constant current circuit and a constant current controller. Background technique [0002] Due to the working characteristics of LEDs, current LED power supplies are mainly driven by constant current. In terms of structure, it is mainly divided into two types: isolation and non-isolation. The isolation scheme and the non-isolation scheme have their own advantages and disadvantages, so both exist in the market. [0003] At present, in the field of low-power LEDs without power factor requirements, three-legged control chips have become the mainstream. The three-legged LED control chip has only three pins, one is the power tube drain pin, one is the power pin, and the other is the current detection pin and the multiplexing pin of the chip. The three-legged LED control chip single-chip integrates power tube, high-voltage start-up, power supply circuit, constant current control, ...

AI Technical Summary

Problems solved by technology

[0006] Based on this, it is necessary to provide a constant current circuit and its constant current controller for the problems that the overvoltage protection caused by the multiplexing of the current detection pin and the chip ground is easily disturbed, and the output overvoltage protection is inaccurate or invalid.

Images