What are the methods to protect the LED circuit? LED is very important for circuit protection circuit is small, from the electronic technology summarized several methods of LED protection circuit, we hope to help the design of LED protection circuit.
Select self recovery fuse
Self recovery fuse is also called high molecular polymer positive temperature thermistor PTC, which is composed of polymer and conductive particles. After special processing, conductive particles form chains in the polymer conductive pathway. When the working current through (or components under normal ambient temperature), the PTC self recovery fuse a low resistance state; when the circuit has abnormal current through (or ambient temperature), high current (or ambient temperature) heat generated by the rapid expansion of the polymer, it cuts off a conductive path a conductive particle, PTC self recovery fuse in a high impedance state; when the current in the circuit (over temperature) disappeared after the polymer cooling volume returned to normal, the conductive particles again form a conductive pathway, PTC self recovery safety wire and a low resistance state initial. In the normal working state of self recovery heating insurance tube is very small, abnormal working conditions in the heat of its high resistance is large, it is limited by its current, which play a protective effect. In the electronic circuit, tage in this small series recommended two options to you:
(1) shunt protection. General LED lamp is divided into many series connected branch. We can add a PTC element in front of each branch to protect. The advantage of this approach is high accuracy and good reliability.
(2) overall protection. Add a PTC element in front of all the light beads to protect the entire light. The benefits of this approach are simple and not accounted for by volume. For civilian products, the results of this protection in practical use are still satisfactory. Two. Protect the LED circuit using fuse (tube)
Because the fuse is disposable, and the reaction is slow, the effect is poor, difficult to use, so not suitable for LED lights fuse finished, because the LED lamp is now mainly in the city of light engineering and lighting engineering. It requires LED protection circuit to be very harsh: can immediately start protection beyond the normal current, let LED power supply channel was disconnected, the LED and the power supply can be protected, in the light then automatically resume normal power supply, does not affect the work of LED. Circuit can not be too complex volume can not be too large, the cost will be low. So it is very difficult to use the fuse.
Three. The use of transient voltage suppression diode (TVS)
Transient voltage suppression diode is a high performance protection device a diode form. When it‘s poles by the reverse transient high energy shock, with 10 minus 12 seconds short time speed, high resistance between the poles themselves immediately reduced to low resistance, absorption up to several kilowatts of power surge, the voltage clamp between two poles at a predetermined voltage value, effective the protection of the precision components in electronic circuit. Transient voltage suppression diodes have fast response time, transient power, low leakage current, breakdown voltage deviation consistency, voltage clamp easier to control, no damage limit, small volume etc..
But in the actual use of electronic components technology users found that it is not easy to find the TVS device to meet the requirements of the voltage value. LED light source is mainly due to the damage caused by the current overheating caused by the internal. TVS can only detect over voltage can not detect over current. It is difficult to choose the appropriate voltage protection point, this device can not be produced in the actual use of.