m29w400b-100za6tr STMicroelectronics, m29w400b-100za6tr Datasheet - Page 14

• Manufacturer Part Number: m29w400b-100za6tr
• Description: 64 Mbit 8mb X8 Or 4mb X16, Multiple Bank, Boot Block 3v Supply Flash Memory
• Manufacturer: STMicroelectronics

Signal descriptions
2.7
2.8
14/74
Write Enable (W)
The Write Enable, W, controls the Bus Write operation of the memory’s Command Interface.
V
The V
use an external high voltage power supply to reduce the time required for Program
operations. This is achieved by bypassing the unlock cycles and/or using the multiple Word
(2 or 4 at-a-time) or multiple Byte Program (2, 4 or 8 at-a-time) commands. The Write
Protect function provides a hardware method of protecting the four outermost boot blocks
(two at the top, and two at the bottom of the address space).
When V
Program and Erase operations in these blocks are ignored while V
even when RP is at V
When V
of the four outermost boot blocks (two at the top, and two at the bottom of the address
space). Program and Erase operations can now modify the data in these blocks unless the
blocks are protected using Block Protection.
Applying V
(including the four outermost parameter blocks) using a High Voltage Block Protection
technique (In-System or Programmer technique). See
details.
When V
Bypass mode. When V
During Unlock Bypass Program operations the memory draws I
programming circuits. See the description of the Unlock Bypass command in the Command
Interface section. The transitions from V
t
Never raise V
memory may be left in an indeterminate state.
The V
become unreliable. A 0.1µF capacitor should be connected between the V
pin and the V
track widths must be sufficient to carry the currents required during Unlock Bypass Program,
I
Table 3.
VHVPP
PP
PP
V
.
V
IH
PP
V
V
/Write Protect (V
PPH
or V
PP
PP
, see
/WP
IL
PP
PP
PP
/Write Protect pin provides two functions. The V
/Write Protect pin must not be left floating or unconnected or the device may
ID
/Write Protect is Low, V
/Write Protect is High, V
/Write Protect is raised to V
PPH
Figure
Hardware protection
SS
PP
to the V
/Write Protect to V
Ground pin to decouple the current surges from the power supply. The PCB
V
IH
17.
V
V
V
RP
or V
IH
ID
ID
ID
PP
PP
.
ID
/WP pin will temporarily unprotect any block previously protected
/Write Protect returns to V
4 outermost parameter blocks protected from Program/Erase
operations
All blocks temporarily unprotected except the 4 outermost blocks
All blocks temporarily unprotected
All blocks temporarily unprotected
PP
/WP)
IL
PP
IH
, the memory protects the four outermost boot blocks;
, the memory reverts to the previous protection status
from any mode except Read mode, otherwise the
PP
IH
the memory automatically enters the Unlock
to V
PP
and from V
IH
or V
Table 3: Hardware protection
Function
PP
IL
function allows the memory to
normal operation resumes.
PP
PP
to V
from the pin to supply the
PP
IH
/Write Protect is Low,
must be slower than
PP
/Write Protect
M29DW640F
for