Open-circuit protection circuit

Abstract

The invention discloses an open-circuit protection circuit, which comprises two branch load circuits of a constant-current driving circuit, a voltage stabilizing unit, an open-circuit detection unit and a short circuit unit. Two connection ends of the voltage stabilizing unit are connected with the two ends, with the same polarity, of the two branch load circuits; the other ends, with the same polarity, of the two branch load circuits have equal potential; the two ends, with the same polarity, of the two branch load circuits are also connected with two input ends of the open-circuit detectionunit respectively; and the output end of the open-circuit detection unit is connected with a control end of the short circuit unit. The open-circuit protection circuit has the advantages of low realization cost and wider application range.

Description

technical field [0001] The invention relates to constant current driving technology, in particular to an open circuit protection circuit. Background technique [0002] A light-emitting diode (LED) constant current drive circuit with multiple outputs generally includes a constant current drive main circuit and at least two load branches, and at least one LED load is connected in series on each load branch. Since the load has multiple branches, in the constant current drive circuit, it is necessary to achieve load current balance on multiple load branches, that is, to realize that the total current output by the constant current drive main circuit is distributed to each LED load according to the load requirements. [0003] In practical applications, to achieve load current balance on the load branch of the LED constant current drive circuit, you can use such as figure 1 In the structure of the LED constant current drive circuit shown, in the drive circuit, a current equalizin...

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Problems solved by technology

[0006] However, the open-circuit protection circuit implemented by short-circuiting the load branch of the thyristor, once an overvoltage occurs, the surge current flowing through the thyristor is very large. Therefore, it is necessary to use a high-current thyristor in practical applications. The implementation cost of the circuit is too high; moreover, if the main circuit of the LED constant current drive circuit adopts BOOST topology, since the BOOST circuit cannot directly connect the load branch short circuit, this open circuit protection circuit will not be applicable to this circuit. Similar to LED constant current drive circuit, the scope of application is small

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