NOR flash finds growing role in automotive designs
TORONTO — As cars get smarter and demand more memory, many technologies are angling for the driver's seat, but it's safe to say NOR flash at least gets to ride shotgun.
As a successor to EEPROM in many applications thanks to its programmability capabilities, NOR flash is finding new opportunities in application areas that need fast, non-volatile memory, including communications, industrial and automotive. The latter, of course, is getting a lot of attention thanks to autonomous vehicle development.
Macronix International, which describes itself as the leading supplier of NOR flash overall, find itself in the third position for automotive. But Anthony Le, senior director of marketing, ecosystem partnership and North America automotive, said the company is confident it will lead that segment in the next two to three years.
Le's career has been well-aligned with the evolution of NOR flash, beginning with his first technology program in the mid-1990s when already NOR flash was able to withstand the high temperatures needed for use under the hood. Today, said Le, that heat tolerance combined with data retention for up 20 years puts Macronix in a good position to capitalize on all the automotive opportunities.
NOR flash got its start in radio — an automotive application that didn't need a lot of memory, said Le. But in the last decade, telematics and all of features and functions in the center console have upped the requirements for memory. Today, you can't sell a car without a digital display. Instead of radios that need 1 megabit of NOR flash, it's clusters that need 12 megabits, even as much as 1 gigabit thanks to all the graphics, he said.
“In a high performing system, like under hood, you can't use any other non-volatile memory besides NOR flash," Le said.
Performance is ultimately what's putting NOR flash in the driver seat today, said Le. “We're getting to the point where you can get almost instant on capabilities because we're able to really boot up the processor at about 500 megabytes per second," he said. When you get into the car and turn on the key, he added, you want that display and that rear-view camera to turn on within a second.
Jim Handy, principal analyst with Objective Analysis, said that “instant-on" is why NOR flash is used in dashboards because it can bring up the basic functionality right away — NOR is better for executing code because special software is needed to manage having your code in NAND flash. “And what you do with that software is that it moves the code from the NAND to a DRAM. And then everything is executed out of the DRAM," he said. “You can execute code right out of the NOR flash, but you can't execute right out of the NAND."
NOR is already in a lot of different parts of the car today, and it will find its way into more because it's good for subsystems, said Handy. If it's got very little code, then it will use a microcontroller that has the NOR inside the microcontroller. But if it's got a larger amount of code because it's a more sophisticated system, then it will have an external NOR flash chip. “You look at today's self-driving cars and all of them have at least one lidar, and each one of those lidars is going to have a NOR flash in it to control the various functions inside that," Handy said.
There was a time when NAND flash was expected sideline NOR flash, but NOR has persevered for several reasons. One is that while NAND does better in applications where you need to store a lot of data, there is a minimum cost for a NAND flash chip, said Handy, so when it comes to smaller amounts of code, you can't buy a fifty-cent NAND flash chip. “You can buy a fifty-cent NOR flash chip," he said. "And it's just more economical for manufacturers of NOR to make a small chip than it is for manufacturers of NAND to make a small chip."
Meanwhile, even automotive-grade NAND can't handle the heat that NOR can, and it doesn't have the reliability for mission-critical automotive applications. Longevity is also a key characteristic of NOR flash, said Macronix's Le, as automakers like stuff that will last a decade to support replacement parts. “We're hearing a lot of pressure for 15 years now. These cars are sitting around, and they still need these parts."
>> Continue reading page 2 of this article on our sister site, EE Times: "NOR flash is road tested."