A multi-channel independently controlled led drive circuit

Abstract

The present invention discloses an LED driver circuit with multi-channel independent control. The circuit comprises a constant current drive circuit that is commonly used by all LEDs, and a plurality of LED branches. The plurality of LED branches are in series connection with the output end of the constant current drive circuit. Each LED branch comprises at least a LED string and a bypass circuit that is corresponding to the LED string and capable of operating in a short circuit or an open circuit. The bypass circuit is connected to the positive and negative electrodes of the LED strings, in order to control the LED lamp in the LED branch to turn on or off in case of a short circuit or an open circuit. The control end of the bypass circuit is connected to a programmable chip and can independently and separately control the LED strings in series connection under the constant current drive power supply.

Description

technical field [0001] The invention relates to the field of LED general lighting, in particular to a multi-channel independently controlled LED driving circuit. Background technique [0002] LED is widely used in general lighting. At the same time, it is often used to express various dynamic effects by connecting colored lights into light strings. As a light source for landscapes, stages, festivals and advertisements, it can reflect two kinds of flickering and flowing water through simple connection and control. Dynamic effect, the whole light string can be divided into a few channels connected in parallel to control them separately, and each branch can be directly loaded by a constant voltage power supply by connecting a certain current limiting resistor in series, even if each branch is driven by a constant current power supply alone It is also feasible, and the driving design is relatively simple. Therefore, this kind of light string is more popular, and it is also comm...

AI Technical Summary

Problems solved by technology

In many occasions, such as building exterior wall lighting, temporary stage construction, amateur cultural performances, outdoor landscapes and advertisements, and enhancement of festival atmosphere, it is necessary to change patterns and use high-power lanterns to achieve a strong enough rendering effect. This kind of professional stage lighting is more complicated, time-consuming and costly to install and disassemble, so the application is limited

[0004] If a single power supply is used and the control circuit is designed with enough output ports, different lamp beads can be simply connected in parallel to the DC constant voltage power supply, and they can be easily controlled independently, but for high-power lamp beads For example, for example, the current passed by a 3W lamp bead is about 700~800mA, and the voltage drop of each lamp bead is between 2V (red LED) and 3~3.5V (blue LED). To obtain colorful changes and dynamic effects, as many independent control branches as possible should be used. For example, 20 circuits require a DC power supply to provide a working current of about 15A. Large currents bring difficulty in device selection and increase costs for power supply design. Low voltage leads to a great reduction in rectification efficiency

[0005] Of course, multiple low-power LEDs can be used in series in each parallel branch or series integrated package (COB) lamp beads to reduce the current and increase the working voltage, but this method is difficult to completely solve the problems caused by parallel connection. The chip-packaged lamp bead is so close to the point light source that it is convenient for light-gathering design. The volt-ampere characteristics of different LED devices are not completely consistent. It is difficult to ensure that the current passing through each path is the same in the parallel connection mode. Due to the different heat dissipation conditions, Also causes inconsistencies in aging and failure times

In order to ensure reliability and working life, it is generally necessary to drive LEDs with a constant current, so multiple LED lamp beads are more suitable to be connected to the constant current drive circuit in series, otherwise the drive circuit can only perform constant current control on the total current, which cannot be guaranteed. The current of each branch connected in parallel is constant, or each LED lamp bead uses a constant current drive power supply alone, resulting in circuit redundancy and complex structure, resulting in reduced reliability

[0006] Even if the parallel LED light group is driven by constant current, it is difficult to ensure that the current distribution of each branch is the same, only the total current can be controlled constant, and it is more difficult to separate the control of different lamp beads in a single series circuit

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