Bus operations
M28W320FCT, M28W320FCB
3
Bus operations
There are six standard bus operations that control the device. These are Bus Read, Bus
Write, Output Disable, Standby, Automatic Standby and Reset. See Table 2: Bus
Operations, for a summary.
Typically glitches of less than 5ns on Chip Enable or Write Enable are ignored by the
memory and do not affect bus operations.
3.1
Read
Read Bus operations are used to output the contents of the Memory Array, the Electronic
Signature, the Status Register and the Common Flash Interface. Both Chip Enable and
Output Enable must be at V in order to perform a read operation. The Chip Enable input
IL
should be used to enable the device. Output Enable should be used to gate data onto the
output. The data read depends on the previous command written to the memory (see
Command Interface section). See Figure 8: Read AC Waveforms, and Table 16: Read AC
Characteristics, for details of when the output becomes valid.
Read mode is the default state of the device when exiting Reset or after power-up.
3.2
Write
Bus Write operations write Commands to the memory or latch Input Data to be
programmed. A write operation is initiated when Chip Enable and Write Enable are at V
IL
with Output Enable at V . Commands, Input Data and Addresses are latched on the rising
IH
edge of Write Enable or Chip Enable, whichever occurs first.
See Figure 9 and Figure 10, Write AC Waveforms, and Table 17 and Table 18, Write AC
Characteristics, for details of the timing requirements.
3.3
3.4
Output Disable
The data outputs are high impedance when the Output Enable is at V .
IH
Standby
Standby disables most of the internal circuitry allowing a substantial reduction of the current
consumption. The memory is in stand-by when Chip Enable is at V and the device is in
IH
read mode. The power consumption is reduced to the stand-by level and the outputs are set
to high impedance, independently from the Output Enable or Write Enable inputs. If Chip
Enable switches to V during a program or erase operation, the device enters Standby
IH
mode when finished.
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NUMONYX [ NUMONYX B.V ]
