New technology: new LED intelligent constant current driver

In the LED industry, it is well known that using constant current source to supply power to LED is the best power supply scheme. In recent years, a variety of constant current drive came into being. Many manufacturers from the definition of "constant flow" of the production of constant voltage power supply years of technology and experience, grafted to the constant current driver, producing constant current driver constant current high precision and the performance is also very good.

The stability of the output current of the constant current driver is mainly affected by the fluctuation of the power supply voltage, the change of LED load and the change of the ambient temperature. The current negative feedback principle of constant current driver using LED current sampling can almost eliminate the influence of various interference factors on the constant current value. We call it an unconditional constant current driver.

High precision constant current driver is the best driver for LED? The actual use shows that the answer is negative. Because its performance does not fully meet the requirements of LED. In the power supply voltage fluctuations, LED load changes, in order to make the LED work stable, constant current is required, but when the use of ambient temperature changes, still keep the constant flow is wrong.

The analysis is as follows:

LED is a semiconductor device, very sensitive to temperature, it has a certain temperature characteristics. Figure 1 is the relationship between the LED operating current and the ambient temperature provided by the LED manufacturer (solid line). It is shown that the operating current of LED should be decreased with the increase of ambient temperature in order to make the LED junction temperature not exceeding the maximum allowable value (about 100 DEG C). According to the practical requirement of LED, we have designed a special LED constant current driver for LED - "intelligent constant current driver". It can load changes in the power supply voltage fluctuation and LED under the condition of constant flow, and in the use of environmental temperature rises, the value of the constant current automatic drop (about 0.3%/ DEG C) to the requirements of the LED values (dotted lines shown). In order to distinguish it from the unconditional constant current, we call this new constant current method conditional constant current.

Using the condition of constant current LED use can prevent overheating in high temperature environment, avoid light effect, reduce light speed, prolong the service life of the LED.

In Figure 1, the output characteristics of the constant current (horizontal dashed line) and the output characteristics of the conditional constant current are shown. They are compared: the unconditional constant current overload starting temperature T1 is lower than the conditional constant current overload starting temperature T2; the LED overload degree is higher than the conditional constant current.

Unconditional constant current, in winter, summer LED is a working current, and conditional constant winter, summer LED working current is not the same, summer working current will automatically reduce. In summer, the working environment temperature is high, it is unfavorable to LED heat dissipation, so it is very reasonable to reduce the working current.

Some people may ask: reduce the LED operating current will reduce the brightness of LED? The answer is: 1, high temperature, appropriate to reduce the working current of LED, to prevent serious overload, greatly prolong its service life, even if the brightness was slightly decreased, and it is worth.

From the figure 2 curve of LED output luminous flux and the junction temperature of 2, we can see that when the working current decreases, junction temperature decrease, LED increase in luminous efficiency, luminous flux also increased (about 0.8%/ degrees), which gives the current decline because of work caused by the flux decline, given a certain amount of compensation. In fact, LED brightness is not obvious, the impact on the normal operation of the LED lamp is small. Almost invisible to the naked eye.

According to the "conditional constant flow" innovative design ideas, we have produced a 0.35A, 0.5A, 0.7A, 0.9A, 1.5A and other 5 series of products.

Their common features are: "three high".

High working reliability

Constant current driver with short circuit, open circuit, open circuit connected to the back, anti shock, anti overheating protection and other functions, (the first two protects the driver after three patentsprotecting LED) can ensure safety of constant current driver and LED lamp under various working conditions. In particular, open and then turn on the impact of the protection of the problem we have breached, and applied for a national patent. Short circuit, open circuit protection power consumption 1W. Working temperature rise 20. Service life of 20000 hours, about 5 years.

Two, high efficiency and energy saving

The highest conversion efficiency of constant current driver is 93%; power factor > > 0.9.

Three, high cost

Good performance, low cost, low price, called "cheap".

Intelligent constant current driver output power range of 25W - 120W, mainly for high-power LED street lamps, such as supporting the use of.