Single inductor mutiple LED string driver and method thereof
A technology of LED light string and common mode inductance, applied in instruments, static indicators, energy-saving control technology, etc., can solve problems such as increasing cost
Inactive Publication Date: 2014-12-03
ACTIVE SEMI SHANGHAI +1
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Problems solved by technology
A boost converter 32 is used to convert the 24V input DC voltage into a specified DC output voltage (VOUT), such as 100 to 200V, output to the front end of the LED light string, and the rear end of each LED light string is respectively converted by, for example, a switch The LED light string switching converter of the device 35 is driven by the LED light string switching converter. The LED light string switching converter is composed of a MOSFET transistor 36, an inductor 37, a diode rectifier 38 and a current detection resistor 39. The working principle of the converter operates to reduce the main output voltage to match the total forward voltage of the LED light string, and then adjust the current of each LED light string to the target value, so that there is no difference between the main output voltage and the total positive voltage of the LED light string. The power loss caused by the voltage difference between the two voltages, however, each LED light string needs to be configured with a LED light string switching converter with a separate inductor, which increases the overall cost
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[0022] Such as Figure 4 As shown, it is a schematic diagram showing the first embodiment of the single-inductor multi-LED light string driver of the present invention. Single inductor multiple LED string driver 40 includes multiple LED strings 41 - 46 , integrated circuit 47 , AC / DC converter 48 , output capacitor 51 , diode rectifier 52 and common mode inductor 53 . Each LED light string contains multiple LED lights linked in series. As shown in the figure, the front end of each LED light string is connected to the DC voltage VHIGH terminal, and the rear end of each LED light string is respectively connected to the LED light switch terminals S1-S6 of the integrated circuit 47, and the rear end of each LED light string Terminals are also electrically connected to holding capacitors 61-66. In addition to the above six LED light switch terminals S1-S6, the integrated circuit 47 also includes a CTRL terminal as a control interface, an ISET terminal as a reference current, a ma...
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A single inductor multiple LED string driver comprises a switch control circuit and a current-sensing control circuit. The switch control circuit generates a plurality of digital control signals that are used to control a plurality of switches coupled to a plurality of strings of LEDs. Each switch is selectively turned on and off by each corresponding digital control signal. The current-sensing control circuit determines an integrated charge amount provided by each current that flows from an input voltage through each LED string, through each switch, through a common inductor, and through a main switch to ground. In response to the determined integrated charge amount, the current-sensing control circuit generates an on-time control signal that controls the on-time of each switch such that the average current flowing across each LED string is equal to each other. Furthermore, the total current flowing across each LED string is regulated to a predefined value.
Description
[0001] This application is to claim the priority of the invention patent with the application number 61 / 402,106 and the invention name "Single Inductor Multiple LED StringDriver" first submitted to the United States on August 23, 2010. technical field [0002] The invention relates to a technology related to power supply, control and protection circuits of LED lamps, in particular to a controller for driving multiple LED lamp strings with a single inductor. Background technique [0003] In the field of general lighting, the application of light-emitting diodes or LED lamps is becoming more and more popular. For example, LED lamps are used in the backlighting of LCD TVs, thin and light laptop display screens, and DLP projector light sources. With the use of LED lights in the field of backlighting, TVs and computer display screens can be designed to be thinner and thinner. The multiple LED light strings designed with LED backlights are arranged in parallel, and the LED lights ...
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IPC IPC(8): G09G3/32
CPCY02B20/42
Inventor 黄树良范文强
Owner ACTIVE SEMI SHANGHAI