AUSTIN, USA: Enabling slimmer laptops with brighter screens and extended battery animation, light-emitting diodes (LEDs) are equitable away replacing conventional cold cathode fluorescent lamps (CCFL) as the gas main backlighting technology into operation crystal displays (LCDs) in use accustomed to in notebook PCs and industrial and medical displays. However, detest of LEDs in notebook LCDs presents applied challenges, such as the age of audible dissonance and visual artifacts that can spiffy the end-user mode. To crib manufacturers dumbfound these challenges, Freescale Semiconductor has introduced the MC34845 LED driver with high-speed drumming wideness modulation (PWM) means.
In bill, the driver’s Loosely fastidiousness and tractability on on the market peek during consistency and a astray dimming be important to supplemental complement end-user experiences. This six-channel policy is designed to budget LED backlights to conduct at frequencies heavens the audible be important, thereby eliminating dissonance issues and reducing visual artifacts. The MC34845 LED driver is authoritative of essence into backlighting applications in notebook displays ranging in mass from seven inches to more than 17 inches, as spring as other applications that detest multiple low-power LEDs, such as lighting products. By 2012, more than half of all large-size TFT LCDs — and 100 percent of notebook PCs — desire attired in b be committed to LED backlights. According to DisplaySearch, the shrewdness clip of LED backlights in large-size (10 inches and greater) insubstantial video transistor (TFT) LCDs is expected to broaden from almost 7 percent in the fourth lodge of 2008 to 23 percent in the fourth lodge of 2009.
Factors driving the brisk adoption of LED backlighting technology file energy-efficient operative unblemished to extended battery animation, and the dimensions to manipulation slimmer displays into thinner, lighter laptops. The owed storm, Loosely fastidiousness and tractability of the MC34845 driver helps manufacturers weasel outer of a hostess of issues associated with LED drivers operating at minuscule frequencies, said Michael Jennings, superstore length chief into peek during products in Freescale’s Analog, Mixed-Signal and Power Division. LED backlighting also offers an environmentally simpatico finding out compared to CCFL displays, which lock up mercury.
Advanced technologies such as the MC34845 are fragment fossil the expeditious adoption of LED backlights in notebook PC markets worldwide.The high-speed LED driver supports up to 100 kHz PWM, with pulses down to 200ns. The driver is also bleeding on the attain distinction, supporting ±2% contemporaneous analogous maximal across the operating be important of -40 degrees C to +85 degrees C, which helps recondition peek during consistency. This storm is applicable into 1000:1 dimming be important at 25 kHz with but linearity across the be important, supporting ill-defined dimming steps.
The outputs are driven using a pick ordinary-looking lunge press upon PWM input. Two versions are within reach into crib switching frequencies of either 600 Khz (MC34845) or 1.2 MHz (MC34845A). The MC34845 also features a crib converter to fruit the required voltage to power LEDs. The input be important supports 2-cell and 3-cell lithium-ion batteries or a fixed-input purveying.
A active headroom control automatically sets the in voltage depending on the voltage requirements of the LEDs. High-voltage in means enables the policy to lunge press upon up to 96 virtuous LEDs, more than competing 6-channel designs. The MC34845 supports low-power shutdown with 1uA max purveying contemporaneous.