The H7A2EG21C1CX (256G-bit) NAND Flash devices include an asynchronous data interface for high-performance I/O operations. These devices use a highly multiplexed 8-bit bus (DQx) to transfer commands, address, and data. There are five control signals used to implement the asynchronous data interface: CE#, CLE, ALE, WE#, and RE#. Additional signals control hardware write protection (WP#) and monitor device status (R/B#).
The H7A2EG21C1CX (256G-bit) NAND Flash device additionally includes a synchronous data interface for high-performance I/O operations. When the synchronous interface is active, WE# becomes CLK and RE# becomes W/R#. Data transfers include a bidirectional data strobe (DQS).
This hardware interface creates a low pin-count device with a standard pinout that remains the same from one density to another, enabling future upgrades to higher densities with no board redesign.
A target is the unit of memory accessed by a chip enable signal. A target contains one or more NAND Flash die. A NAND Flash die is the minimum unit that can independently execute commands and report status. A NAND Flash die, in the ONFI specification, is referred to as a logical unit (LUN).