2, drive circuit, a complex problem:
in terms of voltage matching, unlike ordinary incandescent bulbs, LED can be directly connected to 220 v ac mains. LED is 2-3. V low voltage drive, must to design complex conversion circuit, different USES of LED lights, with different power supply. B. in terms of current supply, the LED of the normal work in 18 ma – 20 ma current, when the power supply current is less than 15 ma LED the luminous intensity is not enough, and more than 20 ma, LED light failure caused by aging, fever increased at the same time, the aging speed, shorten the life, when more than 50 ma soon damaged, in order to prolong the service life of LED light, common integrated circuit, power supply, electronic transformer, separation of components etc and large current drive, with high power tube or silicon controlled rectifier device, additional protection circuit, constant current, constant voltage power supply circuit, power circuit is complex, so failure, components cost, production cost and service cost will be higher. This has greatly limited the competitiveness of the market and buying groups.
Features of the LED lighting circuit:
A, multiple leds matrix structure in series, in parallel;
B, don’t need to control brightness;
C, the LED current to a certain scope changes will not significantly affect the intensity of illumination;
D, LED the cause of the damage is too much electricity, more than 50 ma, smaller voltage change caused by large current changes. So control over current, which provide the basis for simplification of the circuit.
Methods to solve the problem:
WHPTC over-current protector if use for protection, in principle, when the current exceeds the specified value of the circuit when news fast automatic protection, and automatic reset after troubleshooting, without artificial replacement. For leds, and voltage change is not LED the immediate cause of damage, and the increase of current is the real killer of leds. Using this feature, the leds on the circuit protection has the absolute advantage, let the simple power supply into a reality. Practice has proved that in LED circuit fault occurs before the effective protection. As the chart shows, due to the saves WHPTC constant current, constant voltage circuit,. Device cost, production cost and service cost is greatly reduced. Also greatly increase the market competitiveness of products.