LED short-circuit protection circuit for BUCK-BOOST LED drive circuit

Abstract

The present invention relates to the technical field of LED drive circuits, and especially to a LED short-circuit protection circuit for a BUCK-BOOST LED drive circuit. The LED short-circuit protection circuit comprises a comparer, a timer, a first RS trigger, a first NOT gate, a second NOT gate, a third NOT gate and a first NAND gate. The timer comprises a first D trigger, a second D trigger, a third D trigger, a fourth D trigger, a fifth D trigger, a sixth D trigger, a second RS trigger, a first AND gate, a second AND gate, a third AND gate, a fourth AND gate, a second NAND gate, a third NAND gate, a fourth NOT gate, a fifth NOT gate, a sixth NOT gate, a seventh NOT gate, an eighth NOT gate, a ninth NOT gate, a tenth NOT gate and an eleventh NOT gate. The LED short-circuit protection circuit for the BUCK-BOOST LED drive circuit improves the system stability, prevents the chip from being damaged and even bombed in a LED short-circuit condition, and reduces the system input power consumption in the LED short-circuit condition.

Description

technical field [0001] The invention relates to the technical field of LED driving circuits, in particular to an LED short-circuit protection circuit used in a BUCK-BOOST LED driving circuit. Background technique [0002] At present, most Buck-Boost LED drive circuits in the domestic market use traditional voltage technology and require an external power supply system. The positive load terminal of the LED provides the VCC voltage through resistors and diodes. Due to the needs of the market, the inventor has previously developed a BUCK-BOOST LED drive circuit powered by an integrated high-voltage JFET. This drive circuit does not require an external power supply circuit, so it is simpler in system application solutions. The change of LED LED short-circuit protection has also caused new problems. [0003] The traditional Buck-Boost LED drive circuit does not use high-voltage integration technology, and its power supply system is provided by the start-up resistor and the load...

AI Technical Summary

Problems solved by technology

Since the time of Ton_max (maximum conduction time) and Toff_max (maximum demagnetization time) is set internally, the system will work at the working state of Ton_max and Toff_max at this time. Due to the short circuit of the load LED, the system cannot When the current of the inductor is fully discharged, the current of the inductor will become larger and larger. When it increases to a certain extent, the high-voltage MOSFET will be burned and broken down, which will cause the circuit to fail.

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