Load short-circuit protection circuit of LED power supply

A load short-circuit protection circuit of LED power supply comprising a power supply end (100), a load end (200), a switching module (300) disposed between the power supply end (100) and the load end (200), a sampling resistor (400) set in series with the load end (200), a signal amplification module (500) that collects the current change signal of the sample resistor (400), and a protection control module (600) that receives an amplification signal of the signal amplification module (500) and controls the on-off of the switching module (300) according to the signal;

• wherein the signal amplification module (500) comprises a first triode (Q1), a second triode (Q2) and a constant current source (Ro), and when the sampling resistor (400) is disposed at the lower end of the circuit, the first triode (Q1) and the second triode (Q2) employ an NPN type triode;
• the base of the first triode (Q1) is connected to the base of the second triode (Q2), the collector of the first triode (Q1) is connected to the negative electrode of the sampling resistor (400), the emitter of the first triode (Q1) is connected with the protection control module (600) as a signal output end, and the emitter is also connected to a negative electrode of a conversion resistor (R1), a positive electrode of the conversion resistor (R1) is connected to the power supply end (100);
• the collector of the second triode (Q2) is connected to the positive electrode of the sampling resistor (400), the emitter is connected to the negative electrode of the constant current source (Ro), and the positive electrode of the constant current source (Ro) is connected to the power supply end (100).