E S I
I
ES
Excel Semiconductor inc.
DEVICE BUS OPERATIONS
Several device operational modes are provided in
the ES29LV400 device. Commands are used to ini-
tiate the device operations. They are latched and
stored into internal registers with the address and
data information needed to execute the device
operation.
The available device operational modes are listed
in Table 1 with the required inputs, controls, and the
resulting outputs. Each operational mode is
described in further detail in the following subsec-
tions.
on the device address inputs produce valid data on
the device data outputs. The device stays at the read
mode until another operation is activated by writing
commands into the internal command register. Refer
to the AC read cycle timing diagrams for further
details ( Fig. 16 ).
Word/Byte Mode Configuration ( BYTE# )
The device data output can be configured by BYTE#
into one of two modes : word and byte modes. If the
BYTE# pin is set at logic ‘1’, the device is configured
in word mode, DQ0 - DQ15 are active and controlled
by CE# and OE#. If the BYTE# pin is set at logic ‘0’,
the device is configured in byte mode, and only data
I/O pins DQ0 - DQ7 are active and controlled by CE#
and OE#. The data I/O pins DQ8 - DQ14 are tri-
stated, and the DQ15 pin is used as an input for the
LSB (A-1) address.
Read
The internal state of the device is set for the read
mode and the device is ready for reading array data
upon device power-up, or after a hardware reset. To
read the stored data from the cell array of the
device, CE# and OE# pins should be driven to V
IL
while WE# pin remains at V
IH
. CE# is the power
control and selects the device. OE# is the output
control and gates array data to the output pins.
Word or byte mode of output data is determined by
the BYTE# pin. No additional command is needed
in this mode to obtain array data. Standard micro-
processor read cycles that assert valid addresses
Standby Mode
When the device is not selected or activated in a
system, it needs to stay at the standby mode, in
which current consumption is greatly reduced with
outputs in the high impedance state.
ES29LV400E
6
Rev.0B January 5, 2006
EXCELSEMI [ EXCEL SEMICONDUCTOR INC. ]
