LED (light-emitting diode) drive control circuit

Abstract

The invention discloses a LED (light-emitting diode) drive control circuit, which comprises an LED load sampling port, a switch port and a comparison port. An error amplifier module compares the LED load sampling voltage with the reference voltage and amplifies the LED load sampling voltage; a comparison module feeds the voltage of the comparison port and the current sampling signal to a logic processing module after comparing the voltage of the comparison port and the current sampling signal are compared; an open circuit detection protection module detects whether a LED load is open-circuited, detects the duration of the open circuit and outputs the open circuit status signal, an output for a first output end of the open circuit detection protection module and an output of the error amplifier module commonly control the voltage of the comparison port, and a second output end of the open circuit detection protection module outputs the current limiting threshold; a current limiting module feeds the current limiting threshold and the current sampling signal to the logic processing module after the current limiting threshold and the current sampling signal are compared; the logic processing module processes the logic of an input, and the output controls the switch of a power tube through a drive module. The LED drive control circuit prevents the current of an inductor of the LED drive circuit from rapidly rising and avoids the LED load and the power tube being burnt after the LED load is switched on.

Description

technical field [0001] The invention relates to an LED drive control technology, in particular to an LED load open circuit protection technology for an LED drive circuit in a fixed switching frequency step-down mode. Background technique [0002] At present, LED drive circuits can be divided into boost mode and buck mode according to different peripheral topologies, and can be divided into fixed switching frequency and variable switching frequency according to whether the switching frequency changes. Generally, in the LED drive control circuit using boost mode, the designer will take load open circuit protection to prevent the output voltage from getting out of control. However, in the general step-down mode LED drive circuit, especially in the high-power LED drive circuit, the LED drive control circuit with fixed switching frequency step-down mode is widely used. After the load is opened, no detection action is taken inside the chip, such as figure 1 The shown LED drive co...

AI Technical Summary

Problems solved by technology

[0013] After the above-mentioned LED drive circuit is opened, when the LED load is open for a period of time, the voltage of the comparison port COMP continues to rise, and the waveform diagram is as follows image 3 As shown, if the LED load is turned on, especially when the input voltage VIN is high, the external inductor current will suddenly rise to a high level until the LED drive circuit loop is adjusted to a stable value, and the instantaneous high inductor current may damage the LED load and power tube

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