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Simple Discussion On LED Driver
Jul 21, 2017

  Simple discussion on LED driver

  Today, many portable electronic products require a backlight LED driver solution with the following features: DC control, high efficiency, PWM dimming, LED driver over voltage protection, load disconnect, small size and easy to use. This article explores the characteristics of each led drive and how to implement them, and finally describes a typical circuit with each feature.

  LED is a device which is driven by a current, and its brightness is proportional to the forward current. There are two ways to control forward currents. The first is to use the LED I curve to determine the voltage to be applied to the led to produce the desired forward current. Its realization method generally uses a voltage power supply and a town flow resistor. Illustrates this approach. As described below, LED driver there are a number of deficiencies in this approach. Any change in the LED forward voltage will lead to changes in the LED current. If the rated forward voltage is 3.6V, the LED current is 20mA. If the voltage changes to 4.0V, this is a specific pressure change due to temperature or manufacturing changes, LED driver then the forward current is reduced to 14mA. A positive voltage change of 11% results in a larger positive current change of 30%. In addition, according to the available input voltage, the pressure drop and power consumption of the town flow resistance will waste power and reduce the battery life.