What you’ll learn:
- Why serial NAND flash memory is an alternative to serial NOR flash memory.
- What kinds of applications are targeted by each memory type?
Serial NOR flash memory has been a mainstay in low-pin count-storage, providing external code and data storage to microcontrollers. NAND flash memory has maintained the edge on capacity, but it’s typically available as parallel interface memory. Execute-in-Place (XIP) using a quad serial peripheral interface (QSPI) is a popular way to utilize storage with microcontrollers.
I talked with Jun Kawaguchi, Marketing Executive at Winbond, about the company’s QspiNAND serial memory (watch the video above). There’s also an octal incarnation that doubles the throughput.
Of course, the basic difference between NAND and NOR serial flash memory is the underlying transistor architecture. Both are available as parallel memory as well, with the same characteristics. NOR offers good speed but at a higher cost. It supports direct writes, while NAND flash requires a block erase.
The QspiNAND is available in sizes up to 4 Gb. This version and the octal versions are pin-compatible with serial NOR versions.
QspiNAND supports continuous read (see figure). It’s typically used to copy from serial flash to a microcontroller’s RAM. The chips support a transfer rate up to 83 MB/s. They also use error-correction code (ECC) to provide more reliable operation.
Serial NAND can be employed in automotive applications and other solutions where lower-cost, higher-capacity memory is useful.
