Requirements for Reading Array Data
To read array data from the outputs, the system must drive
the CE and OE pins to VIL. CE is the power control and
selects the device. OE is the output control and gates
array data to the output pins. WE should remain at VIH all
the time during read operation. The internal state machine
is set for reading array data upon device power-up, or after
a hardware reset. This ensures that no spurious alteration
of the memory content occurs during the power transition.
No command is necessary in this mode to obtain array
data. Standard microprocessor read cycles that assert valid
addresses on the device address inputs produce valid data
on the device data outputs. The device remains enabled for
read access until the command register contents are
See "Reading Array Data" for more information. Refer to the
AC Read Operations table for timing specifications and to
the Read Operations Timings diagram for the timing
waveforms, lCC1 in the DC Characteristics table represents
the active current specification for reading array data.
Writing Commands/Command Sequences
To write a command or command sequence (which
includes programming data to the device and erasing
sectors of memory), the system must drive WE and CE to
VIL, and OE to VIH. The device features an Unlock Bypass
mode to facilitate faster programming. Once the device
enters the Unlock Bypass mode, only two write cycles are
required to program a byte, instead of four.
The “Byte Program Command Sequence” section has
details on programming data to the device using both
standard and Unlock Bypass command sequence. An
erase operation can erase one sector, multiple sectors, or
the entire device. The Sector Address Tables indicate the
address range that each sector occupies. A "sector
address" consists of the address inputs required to uniquely
select a sector. See the "Command Definitions" section for
details on erasing a sector or the entire chip, or
suspending/resuming the erase operation.
After the system writes the autoselect command sequence,
the device enters the autoselect mode. The system can
then read autoselect codes from the internal register (which
is separate from the memory array) on I/O7 - I/O0. Standard
read cycle timings apply in this mode. Refer to the
"Autoselect Mode" and "Autoselect Command Sequence"
sections for more information.
ICC2 in the DC Characteristics table represents the active
current specification for the write mode. The "AC
Characteristics" section contains timing specification tables
and timing diagrams for write operations.
Program and Erase Operation Status
During an erase or program operation, the system may
check the status of the operation by reading the status bits
on I/O7 - I/O0. Standard read cycle timings and ICC read
specifications apply. Refer to "Write Operation Status" for
more information, and to each AC Characteristics section
for timing diagrams.
When the system is not reading or writing to the device, it
can place the device in the standby mode. In this mode,
current consumption is greatly reduced, and the outputs are
placed in the high impedance state, independent of the OE
The device enters the CMOS standby mode when the CE
& RESET pins ( CE only on 32-pin PLCC & (s)TSOP
packages) are both held at VCC ± 0.3V. (Note that this is a
more restricted voltage range than VIH.) If CE and RESET
(N/A on 32-pin PLCC & (s)TSOP packages) are held at VIH,
but not within VCC ± 0.3V, the device will be in the standby
mode, but the standby current will be greater. The device
requires the standard access time (tCE) before it is ready to
If the device is deselected during erasure or programming,
the device draws active current until the operation is
ICC3 and ICC4 in the DC Characteristics tables represent the
standby current specification.
Automatic Sleep Mode
The automatic sleep mode minimizes Flash device energy
consumption. The device automatically enables this mode
when addresses remain stable for tACC +30ns. The
automatic sleep mode is independent of the CE , WE and
OE control signals. Standard address access timings
provide new data when addresses are changed. While in
sleep mode, output data is latched and always available to
the system. ICC4 in the DC Characteristics table represents
the automatic sleep mode current specification.
Output Disable Mode
When the OE input is at VIH, output from the device is
disabled. The output pins are placed in the high impedance
PRELIMINARY (October, 2002, Version 0.0)
AMIC Technology, Corp.