Latest processor highlights growing demand for memory

  • 19-Jan-2010 09:14 EST

As Renesas boosts memory sizes, it’s providing quicker ways to access data.

Renesas Technology America unveiled a powertrain controller that has 3.75 Mbytes of flash memory, underscoring a growing demand for storage capacity. The CPU also boosts memory speed to improve throughput.

The latest member of the SuperH family, the SH72546R, increases the on-chip flash memory size by 50% to 3.75 Mbytes in response to the industry trend to larger programs. The single-core processor runs at 200 MHz, the same speed as its predecessor, but higher speed memory increases overall performance.

A number of trends in powertrain designs are driving the demand for larger memory sizes. Foremost among them is the push to trim emissions and fuel consumption, which requires more precision and finer granularity in data processing. At the same time, the demand for more programs written in shorter time frames is driving a move to automated code generation, which can yield larger code.

“More customers are moving to model-based design and automatic code generation, though some say that ACG adds 10-20% in overhead,” said Amrit Vivekanand, Automotive Business Unit Marketing Manager, Renesas.

As memory sizes grow, access times are playing a greater role in overall performance. Flash typically runs at slower speeds than logic circuits, which can cause bottlenecks. Renesas addressed that in the new device.

“This flash runs at 100 MHz, which is one of the fastest speeds for flash. That’s important when there a lot of accessing and caching while the CPU is pulling data out of memory,” Vivekanand said.

Memory speed is important, since a CPU running at 200 MHz needs to get data at high speeds, he explained. Many flash blocks run at only 40 MHz, creating bottlenecks. Renesas also employs proprietary caching techniques that consume less power than some competitors, addressing another key system requirement.

The chip also houses another 128 Kbytes of flash memory with functions essentially equivalent to those of EEPROM (electrically erasable programmable read-only memory) for data storage. Using this on-chip flash memory can obviate the need for external memory, helping to reduce system costs.

Though flash sizes are growing steadily, Vivekanand noted that the technology has competition. Magnetic RAM (random access memory) combines the speed of RAM with the nonvolatile storage of flash. MRAM parts are seeing increased commercial usage, and suppliers are ramping up for harsher automotive environments.

“In the next generation or two, we’ll see MRAM cores coming online,” Vivekanand said.

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