Hard Disc Drives (HDDs) have many applications: 3.5-inch HDDs are used mainly for storing data in personal computers and servers, 2.5-inch HDDs are built into notebook PCs, and 1.8- and 1.0-inch drives are used for small information appliances and mobile audio devices. Renesas has a gained a significant market share supplying semiconductor devices for these HDDs. Among the products we have supplied are microcomputers with built-in flash memory, preamplifiers, motor drivers and buffer memory for HDD heads.

Until 1996 we offered these components as individual parts. In 1997, however, we incorporated a microcomputer and a hard disk controller (HDC) into a single-chip SoC device. In 2003 we increased the integration level by combining a microcomputer, HDC and read channel all onto one chip. That SoC now is a popular space-saving component in many 2.5-inch mobile HDDs.

Figure 1 shows a block diagram of the SoC for a 2.5-inch mobile HDD. The chip, built with 0.15µm process technology, integrates a microcomputer, read channel IP, HDC and ATA interface.

The high-speed read-channel IP is one of Renesas' strongest assets. We developed this powerful analog/digital circuit jointly with a major HDD manufacturer. It has outstanding readout and servo controllers, two key elements that allow HDDs to perform better and be more efficient.

Currently, Renesas is developing a SoC for 1.0-inch HDDs that will not use external DRAM as buffer memory. Instead the device will store everything, including the buffer memory, on a single chip by using TCRAM, a highly integrated on-chip memory compatible with the SoC process. This future solution will consume less energy and enable disk drives to become even smaller.

HDDs undergo extremely difficult system performance evaluations. Accurate data readout is essential and drives must achieve very low corrected error rates, on the order of 10^-7. Extremely precise design and manufacture of the discs and read/write heads are required, as are excellent integration with — and close control by — the associated electronic circuits. Accurate testing is essential, too.

Supported by a research laboratory of Hitachi, Ltd. that develops disks and heads, we have developed a system evaluation environment for read channels. We also have established an effective evaluation technology for HDD SoCs (figure 2).

To facilitate one important industry trend, we are taking advantage of the considerable application expertise we have acquired in the process of supplying various semiconductors for DVD recorders, digital video cameras and mobile telephones. Specifically, we're using this expertise to develop SoC solutions tailored for the HDDs needed to implement innovative digital appliance features.

For example, many products in the next generation of digital appliances will have to be able to handle streaming data such as video images. As a result, the HDDs in them will require capabilities different from the capabilities of drives in personal computers. Using our accumulated application knowledge, we are working to optimize HDD SoCs and promote their integration with other semiconductor chips in ways that ensure the fast processing of multimedia content.

One goal of the Renesas system solutions team is to proactively offer innovative and enhanced devices that support customers' product development projects (figure 3). Our fast response gives them a big advantage in markets that change rapidly.