LED constant current driver and LED constant current driving method

Abstract

The invention discloses an LED (Light-Emitting Diode) constant-current driver which comprises an output current detection module, an inductive current zero-cross detection module, an RS (Remote Sensing) trigger, a power switch driver, a cycle timer and a short-circuit protection module, wherein the cycle timer is connected with the setting end of the RS trigger and is used for receiving the output of the inductive current zero-cross detection module; when receiving a zero cross signal, the cycle timer starts timing and resets after timing for preset time; the input end of the short-circuit protection module is connected with the cycle timer and the output end of the short-circuit protection module is connected with the resetting end of the RS trigger; the short-circuit protection module is used for judging whether a sampling resistor is short-circuited, sending out a signal to turn off a master power switch if the sampling resistor is short-circuited, and keeping normal operation of the circuit if the sampling resistor is not short-circuited. The invention also discloses an LED constant-current driving method. The LED constant-current driver is capable of automatically recognizing the normal operation condition and the sampling resistor short circuit condition of a single-stage LED constant-current driver with a source power factor correction function, and well avoiding device explosion or damage caused by superhigh inductive currents generated in a circuit after the sampling resistor is short-circuited.

Description

technical field [0001] The invention relates to circuit protection, in particular to an LED constant current driver and an LED constant current driving method. Background technique [0002] When the LED works normally, it needs to provide a constant DC current, so an LED constant current driver is needed to convert the grid voltage into DC and supply it to the LED. Such as figure 1 As shown, the structure of the LED constant current driver generally includes a semiconductor diode D, an inductor L, a capacitor C, a resistor R and a main power switch S. [0003] In order to achieve accurate control of the current supplied to the LED load, a general LED constant current driver needs a sampling resistor connected in series in the main power circuit, and the output current information can be obtained by sampling the voltage signal at both ends of the sampling resistor, and then Accurate control of the output current is achieved by changing the conduction time of the main power ...

AI Technical Summary

Problems solved by technology

If the inductor current exceeds the maximum current that some devices in the circuit can withstand before the output voltage reaches the overvoltage protection point of the output voltage, the device will be damaged or explode.

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