A multi-channel led drive circuit with open circuit fault detection function

Abstract

The invention discloses a multi-channel LED driving circuit with an open circuit fault detection function, which includes an FB voltage selector integrated in the chip, a plurality of LED current generating circuits, a Boost voltage boosting circuit, and a device for controlling the operation of the Boost voltage boosting circuit. Boost control circuit; each LED current generating circuit is used to provide current for an LED string, and the first end of each LED string is connected to the output voltage of the Boost booster circuit; the FB voltage selector is used to select the voltage of a plurality of LED strings The lowest voltage in the circuit is used as the feedback voltage of the Boost booster circuit, and the channel with an open circuit fault is automatically excluded. The invention integrates the circuit for detecting the open circuit fault into the chip, reduces the system cost, and can automatically restore the power supply on the LED string to make it operate normally when the open circuit fault is restored.

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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