PPDS™ Resources

PPDS® (Point-to-Point Differential Signaling) Overview

Introducing the next-generation in intra-panel interfaces
National’s PPDS architecture provides the features required for the LCD TV market today and into the future. This solution was built from the ground up with the needs of the LCD TV manufacturer in mind and combines a physical layer interface with high-level protocol to create an efficient interface that reduces the overall required PCB size. The PPDS architecture is capable of delivering more than one billion colors to the display (true 30-bit color) and is designed to drive very large panels(up to 90”) at high resolutions (1920 x 1080). This chipset includes a timing controller and a column driver for a complete system solution that drives high-performance TFT LCD panels.

Timing controller
The timing controller uses the industry standard FPD-Link input to receive video data and a PPDS interface output for communication with the column drivers. The timing controller’s advanced data manipulation algorithms, such as National’s response time compensation, create cinema-quality video images. Unlike traditional panel driving schemes, the gamma conversion occurs in the timing controller instead of the column driver. Digitally programmable and independent gamma curves for red, green, and blue provide best-in-class color temperature control. The timing controller operates off of a 2.5V digital supply for lower power and lower EMI, but includes 3.3V I/O cells to be compatible with typical gate driver ICs. All of the functions of the timing controller can be programmed with an external EEPROM to enable rapid prototype and product development.

Column driver
The column driver receives data via the PPDS interface and uses a linear DAC to convert the incoming data to the appropriate output voltage. The column driver also operates at a 2.5V digital supply. Because the column driver uses a linear DAC instead of the traditional non-linear R-DAC, the total number of reference voltages needed for the gamma curve has been reduced from 18 to 6. Overall, the PPDS interface significantly reduces (by up to 50%) the total number of column driver input signals needed.