Route signals to automotive LCDs with low-noise SerDes chips

July 02, 2013 // By Paul Buckley
Texas Instruments has expanded its FPD-Link III automotive-grade SerDes family that provide a low-EMI and high performance path to automotive LCDs.

The DS90UH927Q-Q1 serialiser and DS90UH928Q-Q1 deserialiser deliver uncompressed high-definition (HD) digital video and audio to touchscreen LCD panels in a vehicle’s central information display and rear passenger seats. The DS90UH928Q-Q1 is the only deserialiser to offer automatic cable equalisation, 24-bit colour dithering, and white balancing, over an LVDS connection. These features enable LCD panels to provide the highest performance, lowest cost, and lowest electromagnetic interference (EMI), compared to competitive solutions, TI asserts.
The chipset supports high-bandwidth digital content protection (HDCP), and a direct connection to LVDS input sources and displays, including the OpenLDI (LVDS digital interface) standard. This reduces the number of signal lines by 68% and makes them differential to provide the lowest possible EMI. TI’s FPD-Link family gives system architects a greater number of video sources and displays that can be directly connected to the automotive video network.
The 5-MHz to 85-MHz pixel clock and 24-bit pixel depth combine with on-chip white balancing, high frame rate control dithering, and 7.1 audio support to deliver high-quality video and sound. This provides a consistent look across all car models. The dithering and white balancing feature at HD resolution also saves costs by allowing the use of lower quality LCD panels.
The DS90UB928Q-Q1 adapts automatically to the cable length and the condition or age of the cable. This unique feature addresses cable wear and tear that often occurs with drop-down or pop-up displays, and allows manufacturers to stock fewer LCD panel versions.
The devices carry digital video, audio and bidirectional I 2C control signals concurrently over a single twisted wire pair using the HDCP interface protocol. HDCP and encrypt/decrypt keys are implemented in the SerDes on-chip memory, simplifying system design. This eliminates the cost of microcontrollers and FPGAs that are required with packet-based, compressed video systems using an Ethernet interface.
The DS90UH927Q-Q1 and DS90UH928Q-Q1 can be mixed and matched with other members of TI’s FPD-Link III family to address an