W25M02GV
8.2 Instruction Descriptions
8.2.1 Software Die Select (C2h)
Each stacked die has a pre-assigned “Die ID#” by the factory, in the sequence of 0x00, 0x01, etc. At any
given time, there can only be one Active Die within the W25M package, to communicate with the external
SPI controller. After power-up, Die #0 is always the Active Die. Software Die Select (C2h) instruction is
used to select a specific die to be active, according to the 8-bit Die ID following the C2h instruction as
illustrated in Figure 4.
“Concurrent Operations” can be realized by assigning the current Active Die to perform an Erase/Program
operation which requires some amount of time to finish. While the internal Program/Erase operation is on-
going, the controller can issue a “Software Die Select (C2h)” instruction to select another die to be active.
Depending on the system requirement, a Read, Program or Erase operation can be performed on the
newly selected Active Die. “Read while Program/Erase” or “Multi-Die Program/Erase” can be performed in
such fashion, to improve system Program/Erase throughput and to avoid constant Program/Erase
Suspend and Resume activities in certain applications.
During the device Power-up and Reset time period, it is recommended not to issue “Software Die Select
(C2h)” command to avoid the possible unknown state of the devices. Minimum tVSL (see page 56) and
maximum tRST (see page 60) values can be applied to “Software Die Select (C2h)” command
respectively.
In case of a wrong Die ID is sent to the device, both of the stacked W25N01GV dies may become idle. In
such case, a new “Software Die Select (C2h)” command should be issued followed by a correct Die ID
(0x00 or 0x01) to re-select the Active Die.
Figure 4. Software Die Select Instruction
Publication Release Date: July 1, 2015
- 26 -
Preliminary - Revision B
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