Due to the conduction characteristics of LED PN junction, the power and voltage range of the power supply can be very narrow. If it deviates slightly, it will not be able to lighten the LED or reduce the luminous efficiency, shorten the service life or even burn the chip. The current industrial frequency power supply and the common battery power supply are not suitable for direct supply of LED. The LED driver is the electronic module that can drive LED to work at the best voltage or current state.
1, because LED is a sensitive semiconductor device with negative temperature characteristics, LED driving power (also called driver) is used to protect its stable working state.
2, LED devices for driving power requirements are almost harsh, LED unlike ordinary incandescent bulbs, can directly connect to the 220V exchange of electricity. LED is a low voltage driver, and it is necessary to design complex converter circuits, LED lights for different uses, and different power adapters. To design a good power source, we must consider such factors as efficiency conversion, effective power, constant current accuracy, power supply life and electromagnetic compatibility, because the role of power in the whole lamp is just as important as human heart.
LED drive price
Depending on its power, it is generally between more than 10 and 100 multivariate. Of course, the cost is continuing to decline.
Analysis of several classic LED driver chips
For IC design enterprises to understand what the market needs, what kind of IC should be set in the right price. The price will be changed at any time only for the reference value. Quality and price are the factors that determine whether or not it is used, and it is very important to meet the requirements of the quality parameters of the product design. Price is more important!
Now more and more IC design companies join the LED design team, and design many models. Here, from the aspect of performance price ratio, we will talk about how to choose the right IC and IC to design products.
1, LED driven IC-AMC7150 with mixed market
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. There are dozens of IC models that can be replaced directly by AMC7150 at present, and the price war will not be avoided.
It can be selected in low voltage 4-25V products with low design parameters, and the basic driving capability is designed under 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, which is IC in Europe and America. It is suitable for designing 1-6 LED, and input 6-25V input voltage and SOP8 package form, aiming at the low end spotlight market at present.
3, -CAT4201, CATALYST, USA
This IC drives 1-7 1W LED. The efficiency can be up to 92%, 6-28V voltage input range step-down type drive application design. 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.
The large barrier range current adjustment can adjust the brightness of the potentiometer wide range, such as the design of the lamp and other products.
4, European Zetex company - ZXLD1350
This IC has a good market response and a SOT23 small volume package, and the input 7-30V voltage step-down and constant current drive 1-7psc LED, the line is simple and practical. When the design is designed, Rs should be close to the IC to avoid large power supply voltage, which will affect the effect of constant current.
The overall electronic material cost is slightly higher than the preceding IC.
5. National semiconductor LM3402
The LM3402 market is good. The input voltage range covers the whole automotive application area. The built in MOS tube can be 15 LED at most, and the 1-3 LED is feeling a little expensive, and the cost performance is very good when it is over 5. At present, the customer engineer in contact is highly evaluated, and the acceptance field is more concise and practical. It is the best among the many LED driver IC in the country.
6. National semiconductor LM3404 of the United States
LM3404 and LM3402 line, the different is the current can reach 1A, drive 1-15pcsLED cost-effective.
The above IC specifications are all built-in MOS tubes, and the built-in MOS tube can simplify the circuit design, small volume, lower design comprehensive cost, and the failure rate will be reduced. Because of its current IC process, cost and other reasons more than 1A more than the LED drive IC needs external MOS tube. In our daily product design, we often encounter large current design, such as 5W, 10W and other higher power design requirements. It can only choose IC with external MOS tube. Next, a number of IC will be recommended to facilitate the selection of the majority of the engineers.
7. American credit integrated product company MAX16819/MAX16820
MAX16819/MAX16820 works at 4. 5V to 28V input voltage range, and there is a 5V/10m up voltage regulator. The output current is regulated by the high side current detection resistor, and the special PWM input (DIM) can achieve a wide range of pulse luminance regulation.
MAX16819/MAX16820 is very suitable for applications that require wide input voltage range. High side current detection and built-in current setting circuit can minimize the number of external components and provide a LED current of + 5% precision. In the process of load switching and PWM luminance regulation, the hysteresis control algorithm ensures excellent input power suppression and fast response. MAX16819 has a 30% inductance ripple current, while MAX16820 has a ripple current of 10%. These devices can operate at a switching frequency of up to 2MHz, allowing the use of small components.
MAX16819/MAX16820 can work at -40 degree C to +125 degree C car class temperature range, and can provide 3mm x 3mm x 0. 8mm, 6 pin TDFN package.
Personal suggestion 200-500Hz PWM gray frequency adjustment, 1-6pcs LED string connection maximum 25W product design, recommended price of about 0. About 5 dollars