LED drive circuit and control method thereof

Abstract

The invention discloses an LED drive circuit which comprises an IC drive circuit, a state modulation module and an output power supply module. The IC driving circuit is used for outputting working voltage required by the LED to the output power supply module; the output power supply module is used for rectifying and filtering the working voltage output by the IC driving circuit and then outputting the working voltage to the LED; the state modulation module is used for continuously controlling the IC driving circuit to be periodically and alternately in a working state and a non-working state; when the IC driving circuit is in a working state, the LED is lightened; and when the IC driving circuit is in a non-working state, the LED is not lightened. The state modulation module continuously controls the IC driving circuit to be in the working state and the non-working state periodically and alternately, so that the LED is switched between the lighting state and the non-lighting state, the purpose of adjusting the brightness of the LED is achieved, a special dimming DIM pin is not needed, a power device does not need to be additionally arranged at the output end, the energy consumption is reduced, and the circuit reliability is higher.

Description

technical field [0001] The invention relates to the technical field of LED power drive, in particular to an LED drive circuit. Background technique [0002] People's life has higher and higher requirements for the light quality and brightness of lighting products, so the performance indicators of LED drive power supply are getting higher and higher. Therefore, many LED chip manufacturers have launched various driving solutions to achieve dimming. Effect. Most of the existing solutions adopt two dimming methods: [0003] The first solution: the LED driver chip has a dedicated pin (DIM), which can be a PWM modulation signal, or a (0-10V) modulation signal, which is input into the chip for calculation and comparison, and outputs a signal to control the power device. Turn on and turn off time to achieve the purpose of brightness adjustment; [0004] The second solution: the LED driver chip does not have a dedicated pin (DIM), but a power device is added at the output end, and...

AI Technical Summary

Problems solved by technology

[0005] There are deficiencies in the two existing dimming schemes: the first scheme requires that the LED driver chip must have a dedicated pin (DIM); in the second scheme, when the LED brightness is at 80-90%, the output The current is large, but the power device that controls the current is in a non-complete conduction situation (such as when the PWM duty cycle is 85%). At this time, all the current loss is added to the power device, and the input power of the driving power supply is abnormally increased. The power device that controls the current heats up seriously. In this state, not only cannot save energy, but even damage the LED drive power supply, which directly brings about the adverse consequences of high failure rate of the LED drive power supply.

Images