Design Article
Mobile DDR spurs low-cost, low-power automotive electronics designs
Rich Chaney, Micron Technology
6/12/2008 8:06 AM EDT
Memory density and configuration can have a lot to do with what the mass market demands. This can sometimes be a challenge for automotive electronics since, in terms of the volume of semiconductors it consumes, the auto industry trails markets like computing, server, networking, and even mobile handsets. But Mobile DDR is offered in a variety of densities ranging from 128Mb to 1Gb and is offered in x16 or x32 configurations so that designers can use fewer components to support wide-bus architectures.
[As an example, Micron Technology's 512Mb Mobile DDR devices are offered as a quad-bank where each x16 is 8192 rows by 1024 columns by 16 bits, or as a x32, where each bank is organized as 8192 rows by 512 columns by 32 bits.]
Mobile DDR is also easier to use in a stacked package, like an MCP (multichip package), than some other DRAM devices for several reasons. First, Mobile DDR is edge-bonded. Standard DRAM is commonly center bonded. Additionally, some Mobile DDR products have flexible edge bonding, where the user can select single-edge or dual-edge bonding to best fit their application.
Together, these features make Mobile DDR easier to migrate from generation to generation in a device's life cycle.
Long-term support
Automotive product life cycles often dwarf those of other electronics devices. Think about it: You never hear about someone collecting classic cell phones, but there are thousands of car clubs devoted to collecting classic automobiles.
Automotive designers need to know that they have a stable supply, and Mobile DDR is on the road map for years to come. Designers working now should expect Mobile DDR availability for ten years or more.
Using Mobile DDR, Ford's Sync leads the pack
Sync is a voice-activated, in-vehicle communication and entertainment system that links a Blackberry, Apple iPod Video, Motorola SLVR L7, or any of dozens of other mobile phones and digital-media players directly into a Ford, Lincoln, or Mercury audio-system. The Sync module from Continental and Microsoft is an elegant, low-cost system that gives users robust performance with a total bill of material of just $800 or less according to a recent Automotive DesignLine mini-teardown.
In order to get the Sync's varied features and a customer-friendly price tag, the system's designers had to select components that could meet system requirements, survive extreme automotive temperatures, and were still inexpensive. Now, there's no doubt that Freescale's i.MX31L multimedia processor is the star of Sync's design, but Sync's designers also showed design know-how in choosing Micron's 256Mb Mobile DDR as the system's working memory, which allowed them to take advantage of all of the aforementioned Mobile DDR features for this generation and the next.
Mobile DDR for automotive
While there are a lot of memory options for vehicular electronics, here we have sought to demonstrate that Mobile DDR is a good, high-quality choice for many -applications because it functions in a broad temperature range ("40 to 105C), consumes relatively little power, and is available in a variety of densities and configurations for the automotive market long haul.
Rich Chaney is an electrical engineer and senior manager, Automotive Segment, at Micron Technology.
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