Sophisticated graphics displays in the instrument cluster are a proven way for makers of premium vehicles to add consumer appeal and cachet to new high-end models of car. Audi, for instance, has won rave reviews for its ‘Virtual Cockpit’ instrument cluster in the 2016 TT roadster.

This new type of cluster display is visually exciting, intuitively informative, easily configurable on-the-fly to display different types of data or image appropriately. From a non-technical consumer’s point of view, the cluster is more simply described as cool. The contrast with conventional electro-mechanical dials and gauges is stark. And thanks to the user-interface innovations of smartphones and tablets, today’s car buyers’ appreciation of the performance and appearance of the displays in the cabin is acute. The instrument cluster, in other words, has become an important marketing differentiator in premium vehicles.

The sophisticated graphics display-based instrument cluster has not found its way into the mainstream low-end and mid-range markets for new cars – at least, not yet. There is a very simple reason for this: cost. A graphics display such as that in the 2016 Audi TT, which contains no mechanical dials or gauges, calls for a large TFT LCD display, and an expensive chipset consisting of a high-end microcontroller with a separate high-performance graphics processor unit (GPU). The bill-of-materials cost for such a system is many multiples of the BoM cost of a conventional electro-mechanical cluster.

But if a manufacturer of a mid-range model could produce a more affordable variant of the high-end graphics display in the instrument cluster, it could potentially gain a worthwhile competitive edge. This is why automotive OEMs and tier one suppliers are developing variations on the theme of the ‘hybrid’ cluster with a high-performance graphics display: typically this combines conventional electro-mechanical dials either side of a TFT LCD screen (see Figure 1).

The advantage of this configuration is that the LCD screen can be much reduced in size and resolution compared to the all-electronic display in a high-end vehicle, providing a large BoM cost saving while still enabling the display of sophisticated 2D or 3D graphics. Information types such as mapping or parking assistance can be displayed impressively in 2D or 3D on a display measuring around 3.5” diagonally.

This still, however, leaves the other large component of the system BoM cost of an all-graphics display: the chipset. To satisfy the BoM budget constraints of a mid-range vehicle, a single-chip solution for the entire instrument cluster is required – and this is where migration to the 40nm node has provided a breakthrough. The 40nm node has turned out to be a successful one for the semiconductor industry: yielding well, it is cost-effective while providing great scope to integrate more or better features in a given die size.

And a single-chip instrument cluster design requires a great deal of integration: it might include a high-performance CPU, an LCD controller, high-speed communications interfaces and multiple peripherals. Crucially, it also needs a large, high-speed RAM, since memory capacity is a hard constraint on the display size and display resolution that a system can support.

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http://www.electronics-eetimes.com/design-center/what-40nm-node-means-instrument-cluster