Analysis of AC -free LED's Constant Current Control Technology Analysis

AC -free LED failed to avoid the essential constant current control technology analysis 1. AC -free LED is not the essential change of the device. In other words, there is actually no LED chip that does not have the working mechanism of AC Electric Farm. The AC -free LED that is now available is a specially arranged device in the internal chipset. It is just a change in the internal structure of the LED device. Of course The level of craft is not easy. The introduction of AC -free LED is mostly quoted information published by Seoul Semiconductor. It can be seen that it is a traditional rectifier bridge circuit to solve the problem of communication on the so -called DC LED power supply problem. It seems that the benefit is that the rectifier diode is eliminated, but the reverse resistance of LED is limited. When the grid is in a large peak, it is not necessarily the benefit. Because it is an imitation of the rectifier bridge circuit, only half of the current flows on the four bridge arm, and the DC load flows through the entire current, resulting in the current distribution of the upload of LEDs in each group. And light emitting efficiency, such as overcurrent to cause light decay and affect life. It is simple to solve. Just short -circuit the DC LED is removed. Take a closer look at the circuit, and now it has become positive and reverse LEDs in each group. In fact, you don't have to be too complicated at first. 2. AC -free LED does not avoid the essential constant current control technology. From the introduction, the light effect of AC LED is not higher enough than the usual LED. It is said to be the development stage. The author believes that the foundation of similar LED chips itself is the same. The main thing to restrict the amount of light per tile is the circuit type of the rectifier bridge. Imagine that only one group of LEDs can work normally, giving full play to the light effect, and 80%of the remaining four groups work in the underwriting state with poor light effects. No matter how to develop with it, it is naturally lower than that of ordinary LED's luminous efficiency. The way to improve is to abandon the unreasonable rectification bridge road. There is no constant current protection function in the AC -free LED. When used, it must be connected to the flow resistance. However, when the current at the limit of the power supply voltage is limited, it is necessary to work in the low light effect state of the underlying current when normal or low voltage. The resistance limit is a poor protection method. It not only has defects, but also rely on energy consumption to work, so that the utilization rate of power is reduced. If you want to add a PTC to solve the LED constant current problem, you don't know enough about the performance of the component. PTC is mainly used in overcurrent protection and thermal protection. When the current in the circuit is too large, when the PTC reaches the temperature of the residence after the heat, the resistance value rises sharply to the disconnection. The elimination circuit in the color TV uses it to generate a large current attenuation vapor. Demagnetic. When the PTC resistor is affected by the surrounding heat, the temperature will be opened when the temperature becomes more than the residential point, which can play a role in switching thermal protection. If you want to rely on the positive temperature coefficient characteristics of the PTC resistance to the LED's constant current protection effect: First, the PTC resistance passes the current, there is a heating time process to get hot. The current has already damaged LED. Second, the spontaneous heating temperature of the PTC resistor can really control the constant current. Then the impact of high environmental temperature and low may change dozens of degrees to make this "constant stream value" change meaningless. Is it possible that the common LED devices can also be so simple to flow at the current simple current? Unfortunately. And usually communication constant flow is more troublesome than DC constant current. In fact, there can be all kinds of high quality Product support. Instead of energy, LED manufacturers will be more energetic in terms of circuit technology, and it is better to focus on developing low -cost and high -light LED lighting products.