M29W640FB STMICROELECTRONICS [STMicroelectronics], M29W640FB Datasheet - Page 12

• Manufacturer Part Number: M29W640FB
• Description: 64 Mbit (8Mb x8 or 4Mb x16, Page, Boot Block) 3V Supply Flash Memory
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

2 Signal descriptions
2.7
2.8
12/72
Write Enable (W)
V
The Write Enable, W, controls the Bus Write operation of the memory’s Command Interface.
The V
an external high voltage power supply to reduce the time required for Unlock Bypass Program
operations. The Write Protect function provides a hardware method of protecting the two
outermost boot blocks. The V
When V
Program and Erase operations in this block are ignored while V
when RP is at V
When V
the two outermost boot blocks. Program and Erase operations can now modify the data in the
two outermost boot blocks unless the block is protected using Block Protection.
Applying V
(including the two outermost parameter blocks) using a High Voltage Block Protection
technique (In-System or Programmer technique). See
When V
mode. When V
Bypass Program operations the memory draws I
circuits. See the description of the Unlock Bypass command in the Command Interface section.
The transitions from V
Accelerated Program Timing
Never raise V
memory may be left in an indeterminate state.
A 0.1µF capacitor should be connected between the V
pin to decouple the current surges from the power supply. The PCB track widths must be
sufficient to carry the currents required during Unlock Bypass Program, I
Table 2.
PP
/Write Protect (V
PP
V
V
IH
PP
PP
PP
/Write Protect pin provides two functions. The V
PP
V
V
or V
PPH
/Write Protect is Low, V
/Write Protect is High, V
/Write Protect is raised to V
PPH
/WP
IL
Hardware Protection
PP
ID
PP
to the V
/Write Protect to V
ID
/Write Protect returns to V
.
IH
PP
to V
/WP pin will temporarily unprotect any block previously protected
PP
PP
Waveforms.
V
PP
and from V
IH
/Write Protect pin must not be left floating or unconnected.
RP
V
V
V
/WP)
or V
IL
IH
ID
ID
PP
IH
, the memory protects the two outermost boot blocks;
, the memory reverts to the previous protection status of
ID
from any mode except Read mode, otherwise the
PP
the memory automatically enters the Unlock Bypass
PP
IH
to V
or V
PP
IH
All blocks temporarily unprotected except the 2
IL
2 outermost parameter blocks protected from
from the pin to supply the programming
must be slower than t
normal operation resumes. During Unlock
PP
Table 2: Hardware Protection
All blocks temporarily unprotected
All blocks temporarily unprotected
PP
/Write Protect pin and the V
function allows the memory to use
Program/Erase operations
PP
outermost blocks
M29W640FT, M29W640FB
/Write Protect is Low, even
Function
PP
VHVPP
.
, see
SS
for details.
Figure 13:
Ground