概觀
The serial electrical interface follows the industry-standard serial peripheral interface (SPI), providing a
cost-effective non- volatile memory storage solution in systems where pin count must be kept to a
minimum.
The ISSI IS37/38SML01G1 is a 1Gb SLC SPI-NAND Flash memory device based on the standard
parallel NAND Flash, but new command protocols and registers are defined for SPI operation. It is also
an alternative to SPI-NOR, offering superior write performance and cost per bit over SPI-NOR.
The command set resembles common SPI-NOR command set, modified to handle NAND-specific
functions and new features. New features include user-selectable internal ECC. With internal ECC
enabled, ECC code is generated internally when a page is written to memory array. The ECC code is
stored in the spare area of each page. When a page is read to the cache register, the ECC code is
calculated again and compared with the stored value. Errors are corrected if necessary. The device
either outputs corrected data or returns an ECC error status.
The memory is divided into blocks that can be erased independently so it is possible to preserve valid
data while old data is erased. The device contains 1024 blocks, composed by 64 pages consisting in
two NAND structure of 32 series connected Flash cells. Each page consists 2112-Byte and is further
divided into a 2048-Byte data storage area with a separate 64-Byte spare area. The 64-Byte area is
typically used for memory and error management.
The copy back function allows the optimization of defective blocks management: when a page program
operation fails, the data can be directly programmed in another page inside the same array section
without the time consuming serial data insertion phase.
The pins serve as the ports for signals. The device has six signal lines plus Vcc and ground (GND, Vss).
The signal lines are SCK (serial clock), SI (command and data input), SO (response and data output),
and control signals CS#, HOLD#, WP#.