. I decided to write this quick tutorial for two reasons: First because there are many people who would like to know more about driving and controlling LED lights, and second because i was provided an excellent LED driver chip from Farnell for test, and i wanted to put it under the microscope. So i will place this chip against some other LED drivers to see how good it is. The chip that I'm talking about is the from. It is a Buck-Regulating LED Driver able to drive up to 3A load with constant current, with switching frequencies up to 2 MHz and supply voltage from 9 to 46 volts.
It has an optional PWM input to control the brightness of the LED. The sense voltage is down to 0.18 volts for higher efficiency. The previous description may sound Greek to you, but after reading this tutorial you will be able to design your own LED driver. Special thanks to and for offering three of these chips for test.
You can now start reading the theory pages.
Designing An Led Driver Circuit With Bjts
In the converter circuit in Figure 1, IC 1’s pins 2 and 6 connect together, which lets the device retrigger itself on each cycle. Thus, it operates as a free-running oscillator. During each cycle, capacitor C 2 charges up through timing resistor R 1 and discharges through resistor R 2. Western union gold card recharge phone time. The capacitor charges up to two-thirds of the power-supply voltage, the upper comparator limit, which 0.693(R 1C 2) determines, and discharges itself down to one-third the power-supply voltage, the lower comparator limit, which 0.693(R 2C 2) determines. The total time period, T, is 0.693(R 1+R 2)C 2.
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Figure 1 A free-running 555 timer provides the stimulus for driving a series of LEDs. During the on time, transistor Q 1 conducts and stores the energy in inductor L 1. The foundry nuke x. When it stops conduction, the stored energy transfers to capacitor C 3 through Schottky diode D 1. You can use the following equations to calculate the inductor value.
Led Driver Circuit Design
The selection of an inductor depends on input voltage, output voltage, maximum current, switching frequency, and availability of standard inductor values. Once you know the inductance, you can choose the diode and the capacitor. MOSFET Q 1 determines the duty cycle, according to the following equation. Where I LED is the LED’s current and R SENSE is the sense resistance. The minimum and maximum input and output voltages for this circuit are 10.5 and 15V, respectively. The LED string’s voltage and current are 21V and 350 mA, respectively. The 6W LED driver can find numerous applications, including battery-operated portable lighting, solar-operated garden lighting, automotive lighting, bike headlights, and underwater lights.
Lcd Driver Circuit Design
Driving high-power LED strings with standard off-the-shelf components simplifies your design without sacrificing performance. Related articles:.