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M30LW128D
BUS OPERATIONS
There are 6 bus operations that control each mem-
ory. Each of these is described in this section, see
Tables 4, Bus Operations, for a summary.
On Power-up or after a Hardware Reset the device
defaults to Read Array mode (Page Read).
Typically glitches of less than 5ns on Chip Enable
or Write Enable are ignored by the device and do
not affect bus operations.
Bus Read.
Bus Read operations read from the
memory cells, or specific registers (Electronic Sig-
nature, Status Register, CFI and Block Protection
Status) in the Command Interface.
A valid bus operation involves setting the desired
address on the Address inputs, enabling the de-
vice (refer to Table 3), applying a Low signal, V
IL
,
to Output Enable and keeping Write Enable High,
V
IH
.
The Data Inputs/Outputs will output the value, see
Figure 11, Bus Read AC Waveforms, and Table
16, Bus Read AC Characteristics, for details of
when the output becomes valid.
Page Read.
Page Read operations are used to
read from several addresses within the same
memory page.
Each memory page is a 4 Words or 8 Bytes and
has the same A3-A22. In x8 mode only A0, A1 and
A2 may change, in x16 mode only A1 and A2 may
change.
Valid bus operations are the same as Bus Read
operations but with different timings. The first read
operation within the page has identical timings,
subsequent reads within the same page have
much shorter access times. If the page changes
then the normal, longer timings apply again. See
Figure 12, Page Read AC Waveforms and Table
17, Page Read AC Characteristics for details on
when the outputs become valid.
Bus Write.
Bus Write operations write to the
Command Interface in order to send commands to
the device or to latch addresses and input data to
program.
A valid Asynchronous Bus Write operation begins
by setting the desired address on the Address In-
puts and enabling the device (refer to Chip Enable
section).
Both the Address Inputs and Data Input/Outputs
are latched by the Command Interface on the ris-
ing edge of Write Enable or Chip Enable, whichev-
er occurs first.
Output Enable must remain High, V
IH
, during the
whole Bus Write operation. See Figures 13, and
14, Write AC Waveforms, and Tables 18 and 19,
Write and Chip Enable Controlled Write AC Char-
acteristics, for details of the timing requirements.
Output Disable.
The Data Inputs/Outputs are in
the high impedance state when the Output Enable
is High.
Standby.
When Chip Enable is High, V
IH
, the de-
vice enters Standby mode and the Data Inputs/
Outputs pins are placed in the high impedance
state regardless of Output Enable or Write Enable.
The Supply Current is reduced to the Standby
Supply Current, I
DD1
.
During Program or Erase operations the device
will continue to use the Program/Erase Supply
Current, I
DD3
, for Program or Erase operations un-
til the operation completes.
Automatic Low Power.
If there is no change in
the state of the bus for a short period of time during
Asynchronous Bus Read operations the device
enters Auto Low Power mode where the internal
Supply Current is reduced to the Auto-Standby
Supply Current, I
DD5
. The Data Inputs/Outputs will
still output data if a Bus Read operation is in
progress.
Automatic Low Power is only available in Asyn-
chronous Read modes.
Power-Down.
The device is in Power-Down
mode when Reset/Power-Down, RP, is Low. The
power consumption is reduced to the Power-Down
level, I
DD2
, and the outputs are high impedance,
independent of Chip Enable, Output Enable or
Write Enable.