Multi-channel LED drive circuit with open-circuit fault detection function

Abstract

The invention discloses a multi-channel LED drive circuit with an open-circuit fault detection function. The multi-channel LED drive circuit comprises an FB voltage selector, a plurality of LED current generation circuits, a Boost circuit and a Boost control circuit, wherein the FB voltage selector, the LED current generation circuits, the Boost circuit and the Boost control circuit are integratedin a chip, and the Boost control circuit is used for controlling the Boost circuit to work. Each LED current generation circuit is used for providing current for one LED string, and the first end ofeach LED string is connected with the output voltage of the Boost circuit; the FB voltage selector is used for selecting the lowest voltage in the voltages of the plurality of LED strings as the feedback voltage of the Boost circuit and automatically eliminating a channel with an open-circuit fault. According to the multi-channel LED drive circuit with the open-circuit fault detection function ofthe invention, the circuits for detecting the open-circuit faults are integrated into the chip, so that system cost is reduced, and the power supply on the LED strings can be automatically recovered when the open-circuit faults is recovered, so that the LED strings can operate normally.

Description

technical field [0001] The invention relates to the technical field of LED open-circuit fault detection, in particular to a multi-channel LED drive circuit with an open-circuit fault detection function. Background technique [0002] Traditional LED driver circuits such as figure 1 , the upper and lower terminals of the LED string are respectively connected to the output voltage (Vbst) and the feedback voltage (FB) of the Boost voltage boosting circuit 4', and the Boost voltage boosting circuit 4' is controlled by the Boost control circuit 5'. The Vbst voltage is dynamically adjusted by detecting the FB voltage, so that the LED string has enough cross-voltage to conduct and then emit light. [0003] In the absence of a zener diode (zener diode, D1), when an LED in the LED string has an open-circuit fault, the FB voltage will drop to about 0V, and the Vbst voltage will continue to rise. When Vbst is too high, there may be This causes the diode D2, the external voltage stabil...

AI Technical Summary

Problems solved by technology

[0004] Adding zener diode D1 can avoid damage caused by LED string open circuit, but requires additional components, which will increase the cost of the system

Moreover, the internal circuit of the existing LED driver chip 1' does not have an open-circuit fault detection function, and cannot automatically resume normal operation after the fault is eliminated.

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