HY29LV400 Datasheet, PDF (8/40 Pages) Hynix Semiconductor – 4 Mbit (512K x 8/256K x 16) Low Voltage Flash Memory

HY29LV400
Write Operation
Certain operations, including programming data
and erasing sectors of memory, require the host
to write a command or command sequence to the
HY29LV400. Writes to the device are performed
by placing the byte or word address on the device’s
address inputs while the data to be written is input
on DQ[15:0] (BYTE# = High) or DQ[7:0] (BYTE#
= Low). The host system must drive the CE# and
WE# pins Low and drive OE# High for a valid write
operation to take place. All addresses are latched
on the falling edge of WE# or CE#, whichever hap-
pens later. All data is latched on the rising edge of
WE# or CE#, whichever happens first.
The “Device Commands” section of this data sheet
provides details on the specific device commands
implemented in the HY29LV400.
Standby Operation
When the system is not reading or writing to the
device, it can place the HY29LV400 in the Standby
mode. In this mode, current consumption is greatly
reduced, and the data bus outputs are placed in
the high impedance state, independent of the OE#
input. The Standby mode can be invoked using
two methods.
The device enters the CE# Deep Standby mode
when the CE# and RESET# pins are both held at
V_CC ± 0.3V. Note that this is a more restricted volt-
age range than V_IH . If both CE# and RESET# are
held at V_IH, but not within V_CC ± 0.3V, the device
will be in the CE# Normal Standby mode, but the
standby current will be greater.
The device enters the RESET# Deep Standby
mode when the RESET# pin is held at V_SS ± 0.3V.
If RESET# is held at V_IL but not within V_SS ± 0.3V,
the device will be in the RESET# Normal Standby
mode, but the standby current will be greater. See
Reset Operation for additional information.
The device requires standard access time (t_CE) for
read access when the device is in either of the
standby modes, before it is ready to read data.
Note: If the device is deselected during an erase or
programming operation, it continues to draw active
current until the operation is completed.
Sleep Mode
The sleep mode automatically minimizes device
power consumption. This mode is automatically
8
entered when addresses remain stable for t_ACC +
30 ns (typical) and is independent of the state of
the CE#, WE#, and OE# control signals. Stan-
dard address access timings provide new data
when addresses are changed. While in sleep
mode, output data is latched and always available
to the system.
NOTE: Sleep mode is entered only when the device is
in Read mode. It is not entered if the device is executing
an automatic algorithm, if it is in Erase Suspend mode,
or during receipt of a command sequence.
Output Disable Operation
When the OE# input is at V_IH, output data from the
device is disabled and the data bus pins are placed
in the high impedance state.
Reset Operation
The RESET# pin provides a hardware method of
resetting the device to reading array data. When
the RESET# pin is driven low for the minimum
specified period, the device immediately termi-
nates any operation in progress, tri-states the data
bus pins, and ignores all read/write commands for
the duration of the RESET# pulse. The device also
resets the internal state machine to reading array
data. If an operation was interrupted by the as-
sertion of RESET#, it should be reinitiated once
the device is ready to accept another command
sequence to ensure data integrity.
Current is reduced for the duration of the RESET#
pulse as described in the Standby Operation sec-
tion above.
If RESET# is asserted during a program or erase
operation, the RY/BY# pin remains Low (busy) until
the internal reset operation is complete, which re-
quires a time of t_READY (during Automatic Algo-
rithms). The system can thus monitor RY/BY# to
determine when the reset operation completes,
and can perform a read or write operation t_RB after
RY/BY# goes High. If RESET# is asserted when
a program or erase operation is not executing (RY/
BY# pin is High), the reset operation is completed
within a time of t_RP. In this case, the host can per-
form a read or write operation t_RH after the RE-
SET# pin returns High .
The RESET# pin may be tied to the system reset
signal. Thus, a system reset would also reset the
device, enabling the system to read the boot-up
firmware from the Flash memory.
Rev. 1.0/Nov. 01