Half of the country with PWM dimming control of high brightness LED driver

National Semiconductor announced the industry's first with pulse width modulation (PWM) dimming control function of anode current mode high brightness LED driver. This model LM3433 LED drive is the national semiconductor PowerWise high efficiency series of new products, can drive high power and high brightness LED, especially suitable for the screen backlight system, projector and solid-state lamp. The design of backlight system of national semiconductor LM3433LED driver can support the anode, and the advantages of the design is the common anode can enhance the cooling capacity of the display, so the development of applications, the new LED for example, large LCD screen display television can use stable and reliable LED. In addition, the more compact pocket projector also began to use LED, because LED than the current use of ultra high performance bulbs have a wider color gamut, and more reliable performance, longer life.

Luminus PhlatLight LED is a new generation of LED products, suitable for point light source high brightness lighting system. The PhlatLight red and green blue LED on display at the National Semiconductor booth can output more than 3000 lumens of white light. Luminus LED, vice president of marketing John Langevin said: "PhlatLight has been widely used in a variety of different displays and lighting systems. National Semiconductor's LM3433 drive for our customers to provide a full range of solutions to ensure that the PhlatLight chipset can give full play to its performance. "

American National Semiconductor LM3433 chip is a fixed conduction time DC-DC step-down constant current regulator, can output negative current to drive high power high brightness LED. The output negative voltage constant current can make the anode of the LED can be directly connected to the ground reference chassis, so as to improve the heat dissipation capability of the radiator. Due to the use of a shorter fixed time on the structure of the system, the system can use a small external passive components, no need to add an output capacitor. In addition, the LM3433 chip has two kinds of current control mode to adjust the brightness of the LED. Analog current control mode can use the input signal to regulate the current, in order to provide compensation for different brands of LED. Another current control mode uses logic level dimming to control the input signal to control the brightness of the LED in PWM mode. PWM control mode using parallel switches will be connected with the LED, so that PWM dimming control frequency can be up to 40KHz. The chip also has the function of overheating shutdown protection, VCC undervoltage lockout and logic level shutdown mode and other functions.

LM3433 chip 24 pin LLP package. LM3433 chip to 1000 for the procurement unit, a single price of $2.25, has been bulk supply.

Source: electronic system design