Modified high-efficiency light-emitting diode (LED) drive circuit and drive method

Abstract

In one embodiment, an LED driving circuit can include: (i) a sense circuit configured to sense an inductor voltage, and to generate a sense voltage signal; (ii) a protection control circuit configured to activate a first protection control signal in response to a comparison of the sense voltage signal against a first reference voltage to indicate an LED device is in a first load state; (iii) the protection control circuit being configured to activate a second protection control signal in response to a comparison of the sense voltage signal against a second reference voltage to indicate the LED device is in a second load state; and (iv) a PWM control circuit configured to control a power switch according to the first protection control signal or the second protection control signal, based on the load state of the LED device.

Description

technical field [0001] The invention relates to the technical field of power electronics, and more specifically, relates to an improved high-efficiency LED driving circuit and a driving method. Background technique [0002] With the widespread use of LED lighting, the status of LED driving power is also prominent. The matching of LED driving power directly affects the stability and safety of LED loads. However, in the design of LED driving power supply, it is still a major difficulty to make the driving power supply well matched with different control structures, and have good stability and high power utilization efficiency. The applicant of the present invention applied for a patent application for LED driving power supply in China, the title of which is "A high-efficiency LED driving circuit and driving method". The application was filed on January 10, 2011, and the application number is 201110005323.6 . The content published therein is incorporated herein as figure 1 a...

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Problems solved by technology

[0003] However, in this invention, abnormal load conditions, such as open circuit and short circuit, are not considered. When the load is open circuit, the voltage at the output terminal will become high instantaneously. At this time, if there is no overvoltage protection measure, it will cause waste of energy on the one hand, and on the other hand On the one hand, too high voltage is easy to cause damage to the circuit; and when the load is short-circuited, the input current will drop very slowly after the power switch is turned off. At this time, if the short-circuit protection circuit is not set, in the next cycle When the time comes, the input current will continue to rise because it has not dropped before, causing the input current to be too high and the efficiency to be low

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