M28W640 STMicroelectronics, M28W640 Datasheet - Page 9

• Manufacturer Part Number: M28W640
• Description: 64 Mbit 4Mb x16/ Boot Block 3V Supply Flash Memory
• Manufacturer: STMicroelectronics

SIGNAL DESCRIPTIONS
See Figure 2 Logic Diagram and Table 1,Signal
Names, for a brief overview of the signals connect-
ed to this device.
Address Inputs (A0-A21). The Address Inputs
select the cells in the memory array to access dur-
ing Bus Read operations. During Bus Write opera-
tions they control the commands sent to the
Command Interface of the internal state machine.
Data Input/Output (DQ0-DQ15). The Data I/O
outputs the data stored at the selected address
during a Bus Read operation or inputs a command
or the data to be programmed during a Write Bus
operation.
Chip Enable (E). The Chip Enable input acti-
vates the memory control logic, input buffers, de-
coders and sense amplifiers. When Chip Enable is
at V
mode. When Chip Enable is at V
deselected, the outputs are high impedance and
the power consumption is reduced to the stand-by
level.
Output Enable (G). The Output Enable controls
data outputs during the Bus Read operation of the
memory.
Write Enable (W). The Write Enable controls the
Bus Write operation of the memory’s Command
Interface. The data and address inputs are latched
on the rising edge of Chip Enable, E, or Write En-
able, W, whichever occurs first.
Write Protect (WP). Write Protect is an input
that gives an additional hardware protection for
each block. When Write Protect is at V
Down is enabled and the protection status of the
block cannot be changed. When Write Protect is at
V
be locked or unlocked. (refer to Table 6, Read Pro-
tection Register and Protection Register Lock).
Reset (RP). The Reset input provides a hard-
ware reset of the memory. When Reset is at V
the memory is in reset mode: the outputs are high
impedance and the current consumption is mini-
mized. After Reset all blocks are in the Locked
state. When Reset is at V
IH
, the Lock-Down is disabled and the block can
IL
and Reset is at V
IH
IH
, the device is in normal
the device is in active
IH
the memory is
IL
, the Lock-
IL
,
operation. Exiting reset mode the device enters
read array mode, but a negative transition of Chip
Enable or a change of the address is required to
ensure valid data outputs.
V
vides the power supply to the internal core of the
memory device. It is the main power supply for all
operations (Read, Program and Erase).
V
provides the power supply to the I/O pins and en-
ables all Outputs to be powered independently
from V
separate supply.
V
control input and a power supply pin. The two
functions are selected by the voltage range ap-
plied to the pin. The Supply Voltage V
Program Supply Voltage V
any order.
If V
V
age lower than V
against program or erase, while V
ables these functions (see Table 14, DC Charac-
teristics for the relevant values). V
sampled at the beginning of a program or erase; a
change in its value after the operation has started
does not have any effect on Program or Erase,
however for Double or Quadruple Word Program
the results are uncertain.
If V
power supply pin. In this condition V
stable until the Program/Erase algorithm is com-
pleted (see Table 16 and 17).
V
measurements.
Note: Each device in a system should have
V
pacitor close to the pin. See Figure 8, AC Mea-
surement Load Circuit. The PCB trace widths
should be sufficient to carry the required V
program and erase currents.
DD
PP
PP
SS
DD
DDQ
PP
PP
, V
Ground. V
is seen as a control input. In this case a volt-
Program Supply Voltage. V
Supply Voltage (2.7V to 3.6V). V
Supply Voltage (1.65V to V
is kept in a low voltage range (0V to 3.6V)
DD
is in the range 11.4V to 12.6V it acts as a
DDQ
. V
and V
DDQ
PPLK
SS
can be tied to V
PP
M28W640CT, M28W640CB
is the reference for all voltage
decoupled with a 0.1µF ca-
gives an absolute protection
PP
can be applied in
DD
PP
PP
or can use a
PP
DD
> V
PP
DD
is both a
). V
must be
DD
and the
PP1
is only
DDQ
pro-
9/54
en-
PP