Power regulation circuit for linear LED (light-emitting diode) drive power supply

Abstract

The invention provides a power regulation circuit for a linear LED (light-emitting diode) drive power supply. The power regulation circuit comprises a detection circuit and a control circuit, wherein the input end of the detection circuit is connected to a detection point and second reference voltage, the detection circuit is configured to output a first signal when judging that the voltage of the detection point and the second reference voltage meet a preset relationship, and the voltage of the detection point is linearly proportional to voltage applied to an LED; the input end of the control circuit is connected to the output end of the detection circuit, the output end of the control circuit is connected to a gate of a first MOS (metal oxide semiconductor) transistor, and the control circuit is configured to control the first MOS transistor to be switched off when receiving the first signal from the detection circuit. According to the power regulation circuit, when the value of input voltage is higher than a threshold value, the MOS transistor is switched off through the control circuit to reduce power loss during high-voltage input; in addition, reference voltage of a compensation circuit is changed to increase current during low-voltage input and reduce current during high-voltage input to meet the requirements of a user on linear regulation rate and load regulation rate.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a power adjustment circuit for a linear LED driving power supply. Background technique [0002] The structure of linear LED drive power supply is as follows: figure 1 As shown, the AC input signal is converted into an input voltage by a rectifier circuit. The LED load is connected in series with the MOS transistor Q1 and the CS sampling resistor R1. The characteristic of this circuit is that the power varies with the input voltage. When the voltage compensation is added from the drain of the MOS transistor Q1, the change of the input power with the input voltage can be improved to a certain extent, but there is usually a power change of more than 10%. [0003] As the input voltage increases, the loss of the circuit will also increase greatly, resulting in a decrease in the efficiency of the circuit at high voltage input and severe heat generation. This makes the user need t...

AI Technical Summary

Problems solved by technology

[0003] As the input voltage increases, the loss of the circuit will also increase greatly, resulting in a decrease in the efficiency of the circuit at high voltage input and severe heat generation.

This makes the user need to increase the heat dissipation area of ​​the linear circuit chip when using the circuit, which increases the system cost and design difficulty

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