Driver lights LEDs more uniformly

LED panel manufacturers will be able to produce higher quality images more easily using a next-generation driver device that reduces channel and chip skews to new lows.

Macroblock reckons its new generation LED driver, the MBI5025, offers the world's best LED uniformity.

Using advanced PrecisionDrive technology, maximum output current variations between channels (or channel skew) and between drivers (chip skew) are as low as 2 and 3%, respectively.

The precise output current control delivers more uniform colour or brightness of LEDs, improving the image quality and colour performance of LED display panels.

"Macroblock is proud to facilitate customers to produce the LED display panels with best image quality", says Robert Chen, General Manager of Macroblock.

"It is our commitment to continuously innovate and contribute".

To maintain the quality from each LED module to each LED display panel, Macroblock's continuous uniformity improvements on the new generation LED drivers will greatly benefit manufacturers in minimising variations during the manufacturing process, being able to keep the stability and consistency within LED modules and within different LED display panels and save the manufacturing costs.

Realising that minimising the output current variation is essential when it comes to display quality and manufacturing improvements of LED display panels, Macroblock has been dedicated to upgrade the uniformity of LED drivers in every possible way.

In terms of IC design, the channel skew and chip skew are caused by the mismatch of devices inside the IC and inconsistency between different batches of ICs.

Mismatch means the geometric difference between two devices fabricated at the same time, and inconsistency means the electrical difference between two devices fabricated at different times.

Process mismatch and inconsistency are unavoidable, but Macroblock minimises the imperfections through three steps: first, the elegant circuit design suppresses the effects of mismatch and inconsistency; secondly, a more consistent and controlled fabrication process minimises the output current variation and maintains the quality of the IC; and finally, 100% testing and qualification filters the ICs with best uniformity.

In the past, LED display panel manufacturers used drivers with constant voltage output to drive LEDs, such as the 74HC595.

But this makes it difficult to control the image quality of LED display panels because of the inconsistent colour and brightness of individual LEDs.

To improve the image quality of LED display panels, a constant current LED driver is used to improve LED uniformity, but the skew of output current is still very large.

Then Macroblock unveiled the famous PrecisionDrive MBI5026 LED driver, to lower the channel skew and chip skew to +/-3 and +/-6%, respectively.

This limitation of current variation soon became the standardised specification on the LED display market because it not only noticeably improves the image quality of LED display panels but also extends the lifetime of LEDs when compared with constant-voltage LED drivers.

However, human eyes can distinguish 6% brightness difference, and may be even sensitive to 1% difference when an LED display panel is in a low-brightness configuration.

The most common problem is the inconsistent brightness within LED display modules.

And these brightness differences are usually caused by the mismatch of LEDs or the different batches of LED drivers.

Facing the current challenges of the mismatch of LEDs and different batches of LED drivers, Macroblock has now improved the channel skew and chip skew to +/-2 and +/-3%.

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