4-channel video decoder delivers improved images in automotive designs

February 17, 2015 // By Graham Prophet
Intersil’s TW9984 is designed to boost 360-degree surround image quality in advanced driver assistance systems.

The device is a four-channel analogue video decoder with built-in analogue video encoder for around-view parking assist applications, providing improved safety for drivers and pedestrians. The TW9984 replaces up to nine discrete components with a single chip, to provide a high level of picture quality in generated-360-degree surround images for advanced driver assistance systems (ADAS).

An around-view monitor system, also referred to as a surround view monitor, processes video from four cameras and then combines the four images into a single birds-eye, top-down view as if a camera was stationed directly above the vehicle. The monitor helps drivers visually confirm the vehicle’s position relative to surrounding objects for easy manoeuvring and parking.

The TW9984 integrates four high quality NTSC/PAL analogue video decoders with 10-bit analogue-to-digital converters (ADCs) to support four analogue camera inputs simultaneously. A flexible digital output interface makes it easy for the system designer to send the images to a processor that can then combine the four images into a single unified around-view image. The on-chip analogue video encoder provides the ability to transmit the combined video as a standard analogue composite signal to the head unit display. The TW9984 also incorporates analogue anti-aliasing filters on each channel input to further reduce component count. The high level of integration helps to simplify the system design and minimise the solution footprint to preserve critical board space.

Features include;

• Integrates four NTSC/PAL analogue video decoders and 10-bit ADCs with differential, pseudo differential and single-ended inputs

• Integrates one analogue video encoder to re-encode video to CVBS format

• Integrates programmable automotive short diagnostics - short-to-battery and short-to-ground detection - on each differential input channel

• Supports 108 MHz time multiplexed ITU-R BT.656 format to output four channels over a single 8-bit data bus

• Integrated PLL generates the 108 MHz output while using a lower cost 27 MHz crystal oscillator on the board

• Consumes approximately 100 mW per