New Development in Common-cathode Technology: How Super fine pitch Era Empowers LED Displays




New Development in Common-cathode Technology: How Super fine pitch Era Empowers LED Displays


This is an extract translation of an article published by the Hangjianet on January 5, 2022.
Visit for the original article.

According to the coming White Book on Super fine pitch LED 2021 released by the Hangjianet Research, the market for sub-P1.0 super fine pitch displays jumped 75.53% in 2021 as the world LED display market grew to RMB 51.9 billion.

           Source: White Book on Super fine pitch LED 2021, Hangjianet

As pitch continues to shrink, pixel density increases, driving up display energy consumption. Since it’s more important to cut energy consumption than ever, choosing between common-anode and common-cathode technology becomes a technology roadmap issue in the sub-P1.0 super fine pitch era. The industry is attracted to common-cathode technology as it is more energy-efficient than its common-anode counterpart.

              Source: White Book on Super fine pitch LED 2021, Hangjianet

Based on how common-anode and common-cathode technology works, the latter can meet the varying voltage need of different chips by supplying voltage separately since red LED chip has a different threshold voltage from green and blue LED chips. In other words, the technology can provide red LED chip with a voltage lower than what green and blue LEDs need.

       Source: White Book on Super fine pitch LED 2021, Hangjianet

The technical principles show common-cathode technology has the following advantages over common-anode technology.
Common-anode technology generally supplies red LED chip, green LED and blue LED chip with the same voltage (>3.8V), which wastes energy. On the other hand, common-cathode LED display provides red, green and blue chips with the voltage respective LED needs, i.e. less than 2.8V for red LED chip and about 3.8V for green and blue LED chips. By supplying each with the precise voltage, less energy is wasted, which reduces heat produced by operating LED displays. The precision supply enables common-cathode technology to cut voltage to the red LED chip to reduce overall power consumption, waste heat, LED display temperature and LED wear and tear, which in turn improve system stability and reliability. 

Nevertheless, common-anode technology has some advantages too. Hangjianet Research shows common-anode technology has a market share of 90%, comparing to common-cathode's 10% due to the following factors
1) Common-anode technology has matured with a comprehensive supply chain. Common-cathode technology is not as mature in terms of LED, power supply and driver among other supports.
2) Though common-cathode technology reduces the voltage supplied to the red LED chip as it has a lower VF, it introduces complexity to the power supply and PCB layout.   
3) Hangjianet Research data indicates common-anode design is more cost competitive as common-cathode technology costs about 30% more.
4) More importantly, as a single business (Silicon-Core Technology) owned most of the key common-cathode patents, display manufacturers were concerned about intellectual property (IP), which had a major impact on the development of common-cathode technology. That is why most available offerings are based on common-anode technology though common-cathode designs can save significant energy.

Source: White Book on Super fine pitch LED 2021, Hangjianet

5) As we examine the issue from the angles of energy saving and heat reduction, we will find normal pitch LED displays have been commodified. Though the demand exists, it’s not enough to drive the introduction of costly common-cathode technology. Being more technical matured and less expensive, common-anode technology is often preferable. On the other hand, since saving energy and reducing temperature are more critical to super fine pitch displays, common-cathode technology is better suited to sub-P1.0 super fine pitch displays whose market share continue to grow.

But common-cathode technology may see some new applications next year (2022).
First, aforementioned data shows super fine pitch LED displays are ramping up at an increasing rate every year. As LED displays continue to miniaturize and market share keeps rising, the need for low power consumption and temperature will only increase, fueling the demand for common-cathode technology.  

Second, Hangjianet Research data indicates there are new solutions to the patent issue. It is reported that the leading driver supplier continues to work on common-cathode patents. The latest Macroblock common-cathode chips MBI5754 and MBI5759 can achieve the same display performance as common-anode architecture. MBI5754 meets Macroblock’s HDR-Optimized standard at 64 scans (16-bit/ 3,840Hz) and MBI5759 meets the standard at 32 scans (16-bit/ 3,840Hz). Most importantly, the US Patent Office has certified their new circuit architecture, freeing them from the application and marketing restrictions of legacy patents. The breakthrough development is great news to introducing common-cathode technology to the patent-sensitive international market.

            Source: Official Macroblock website, Hangjianet Research

Therefore super fine pitch products are in the early stage of commercialization with superior added value, which is conducive to introducing common-cathode technology that costs somewhat more. While the ramping up of super fine pitch products will bolster the demand for common-cathode technology, the arrival of additional common-cathode patents will also help the supply chain tilt toward the technology in general. Common-cathode technology is expected to go mainstream by leveraging a wave of super fine pitch offerings.