Because the LED PN junction conduction characteristics, it can adapt to the power supply voltage and current range is very narrow, slightly deviated from May to light the LED luminous efficiency or reduce seriously, or shorten the service life and even burn the chip. The power supply current and battery power supply common are not suitable for direct supply of LED, LED is the driver can drive the electronic component LED in the best voltage or current condition.
1, because the LED is sensitive to the characteristics of semiconductor devices, and has a negative temperature characteristic, the LED driver (also called drive) is a stable working state to protect it in the application process.
2, LED devices on the drive power requirements almost harsh, LED unlike ordinary incandescent bulb, can directly connect 220V AC city power. LED is low voltage drive, must design complex conversion circuit, different uses of LED lights, to be equipped with different power adapter. The design of a good power supply must be integrated into the conversion efficiency, effective power, constant current accuracy, power life and electromagnetic compatibility of these factor, because the power in the whole lamp acts as a human heart is as important as.
LED drive price
As far as its power is concerned, it is usually between more than 10 and 100 yuan. Now, of course, the cost continues to decline.
Common several classic LED driver chip analysis
IC design enterprises to understand what kind of market needs IC, what price should be appropriate. Prices will change at any time, only for reference values. Quality and price are the key factors to decide whether to adopt or not. It is very important to meet the requirements of product design quality parameters! Price is more important!
Now IC design more and more manufacturers to join the LED design team, the design of many types, based on the ratio of performance to price in detail about how to choose appropriate IC, which IC is the most suitable to prepare their own product design.
1, the market is mixed with LED drive IC-AMC7150
At the time of AMC7150 is good, I want to still want to make it, there is a very important factor is the price, there is no market price of 2 yuan, the reason for it is you. AMC7150 now has dozens of IC models that can be replaced directly, and the price war can not be avoided.
The low voltage 4-25V products with low design parameters can be selected, and the basic drive capability is below 3W. For example, 1W string 3 or 3W 1 LED design is stable.
2, Hangzhou Silan microelectronics -SB42511
At the launch of the new IC Silan semiconductor, is mainly aimed at driving the 24V drive 6 of the LED market. The price is higher than that of AMC7153 in Europe and the United States preferential market IC, suitable for the design of 1-6 LED input, 6-25V input voltage, SOP8 package, mainly aiming at the low-end market spotlight.
3, American CATALYST company -CAT4201
This IC drives 1-7 1W LED. Design of Buck drive application with efficiency up to 92% and 6-28V voltage input range. The maximum ratio of two in front of the advantage of IC is SOT23 package size, line, with the majority of small cup design requirements.
High resistance range current adjustment, can potentiometer wide resistance range to adjust brightness, such as the design of table lamps and other products need to do so.
4, European Zetex company - ZXLD1350
This IC is currently a good market response, but also SOT23 small volume package, input 7-30V voltage step-down constant current drive 1-7psc LED, the circuit is simple and practical. When designing, Rs should be close to IC to avoid the large supply voltage, which will affect the constant current effect.
The overall electronic material cost is slightly higher than the preceding IC.
5. National semiconductor LM3402
LM3402 market reflects the good, the input voltage range covers the entire automotive applications, built-in MOS tube up to 15 LED, the 1-3 LED is feeling a little expensive, more than 5 when the price is very good. At present, the customer engineers are highly valued, and they are widely accepted in the field. The lines are simple and practical, and they are among the most numerous LED drivers in IC.
6. National semiconductor LM3404
LM3404 and LM3402 as the line, the difference is that the current can reach 1A, drive 1-15pcsLED cost-effective.
All the IC specifications listed above are built in MOS tubes, and the built-in MOS tube can simplify the circuit design, reduce the design cost, and reduce the failure rate. Because of its current IC process, cost and other reasons, more than 1A of LED drive IC requires external MOS tube. In our daily product design often encountered in the current design, such as 5W, 10W and other design of higher power requirements, it can only choose external MOS tube IC can. The next comprehensive cost recommend several IC, for the vast number of engineers friend type selection convenience.
7, the United States letter integrated product company MAX16819/MAX16820
MAX16819/MAX16820 works at 4. 5V to 28V input voltage range, and there is a 5V/10m voltage regulator on chip. The output current is regulated by a high side current detection resistor, and a dedicated PWM input (DIM) can be used to achieve a wide range of pulse brightness regulation.
MAX16819/MAX16820 is well suited for applications requiring wide input voltage range. The high side current detection and the built-in current setting circuit make the number of the external components least, and provide the LED current with a precision of 5%. In the process of load switching and PWM brightness adjustment, the hysteresis control algorithm guarantees excellent input power suppression and fast response. The MAX16819 has 30% inductor ripple current, while the MAX16820 has a ripple current of 10%. These devices can operate at switching frequencies up to 2MHz, allowing small components to be used.
MAX16819/MAX16820 can work at -40 degrees C to +125 degrees C automotive temperature range, which can provide 3mm x 3mm x 0. 8mm, 6 pin TDFN package.
Personal recommendation 200-500Hz PWM gray frequency adjustment, 1-6pcs LED series connection maximum 25W product design, recommend about 0 of the price. About 5 dollars