An inductor current valley value detection method and a constant current control method for an LED drive circuit

Abstract

The invention discloses an inductor current valley value detection method and a constant current control method for an LED drive circuit, belonging to the technical field of electronic circuits. Inductor current valley value detection method The method for detecting the inductor current valley value in the nth working cycle of the LED drive circuit is as follows: firstly, the average current of the inductor current is calculated by using the reference voltage of the LED drive circuit and the sampling resistor; The maximum value of the voltage across the sampling resistor in n working cycles; according to the fact that the current flowing through the sampling resistor is the same as the current flowing through the inductor, use the maximum value of the voltage across the sampling resistor and the sampling resistor to calculate the value of the inductor current in the nth working cycle Peak value; finally, the valley value of the inductor current is calculated by using the average current and peak current of the inductor current in the nth duty cycle. The constant current control method of the LED driving circuit realizes constant current control by setting the valley value of the inductor current in each working cycle to the valley current of the inductor current in the previous working cycle.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and in particular relates to a method for detecting a valley value of inductance current and a constant current control method for detecting an LED drive circuit. Background technique [0002] LED has become the mainstream of today's lighting sources because of its energy saving, high reliability, long life and environmental friendliness. In the field where the LED power is less than 20W, the buck topology non-isolated structure is mainly used to drive, which not only ensures the conversion efficiency but also ensures a high cost performance. On the other hand, because of the unique current-voltage transfer characteristics of LEDs, small voltage fluctuations will produce large current fluctuations, so now a constant current method is generally used to drive LEDs to ensure that the brightness of LEDs remains stable, while usually The average value of the inductor current is used to ch...

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Problems solved by technology

[0007] Aiming at the problem that the above-mentioned sampling resistor between the power switch tube and the ground cannot detect the valley current of the LED constant current drive circuit of Buck topology in the traditional peak current control mode, the patent number of this invention is ZL2014102500721, and the patent name is a kind of Based on the current control method proposed by the constant current output control device of the LED drive circuit, a valley current detection method and a method for realizing constant current control using the valley current detection method proposed by the present invention are proposed, avoiding the The valley current cannot be determined while the average current is uncertain or even not constant, and the average current cannot be precisely controlled

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