P30
9.1.2
Writes
To perform a write operation, both CE# and WE# are asserted while RST# and OE# are
deasserted. During a write operation, address and data are latched on the rising edge
of WE# or CE#, whichever occurs first. Table 23, “Command Bus Cycles” on page 45
shows the bus cycle sequence for each of the supported device commands, while
Table 24, “Command Codes and Definitions” on page 46 describes each command. See
Section 7.0, “AC Characteristics” on page 28 for signal-timing details.
Note: Write operations with invalid VCC and/or VPP voltages can produce spurious results and should
not be attempted.
9.1.3
9.1.4
Output Disable
When OE# is deasserted, device outputs DQ[15:0] are disabled and placed in a high-
impedance (High-Z) state, WAIT is also placed in High-Z.
Standby
When CE# is deasserted the device is deselected and placed in standby, substantially
reducing power consumption. In standby, the data outputs are placed in High-Z,
independent of the level placed on OE#. Standby current, ICCS, is the average current
measured over any 5 ms time interval, 5 μs after CE# is deasserted. During standby,
average current is measured over the same time interval 5 μs after CE# is deasserted.
When the device is deselected (while CE# is deasserted) during a program or erase
operation, it continues to consume active power until the program or erase operation is
completed.
9.1.5
Reset
As with any automated device, it is important to assert RST# when the system is reset.
When the system comes out of reset, the system processor attempts to read from the
flash memory if it is the system boot device. If a CPU reset occurs with no flash
memory reset, improper CPU initialization may occur because the flash memory may
be providing status information rather than array data. Flash memory devices from
Numonyx allow proper CPU initialization following a system reset through the use of the
RST# input. RST# should be controlled by the same low-true reset signal that resets
the system CPU.
After initial power-up or reset, the device defaults to asynchronous Read Array mode,
and the Status Register is set to 0x80. Asserting RST# de-energizes all internal
circuits, and places the output drivers in High-Z. When RST# is asserted, the device
shuts down the operation in progress, a process which takes a minimum amount of
time to complete. When RST# has been deasserted, the device is reset to
asynchronous Read Array state.
Note: If RST# is asserted during a program or erase operation, the operation is terminated and the
memory contents at the aborted location (for a program) or block (for an erase) are no longer
valid, because the data may have been only partially written or erased.
When returning from a reset (RST# deasserted), a minimum wait is required before the
initial read access outputs valid data. Also, a minimum delay is required after a reset
before a write cycle can be initiated. After this wake-up interval passes, normal
operation is restored. See Section 7.0, “AC Characteristics” on page 28 for details
about signal-timing.
Datasheet
44
November 2007
Order Number: 306666-11
NUMONYX [ NUMONYX B.V ]
