March 8, 2002 Am49DL640BG 19
PRELIMINARY
The alter nate meth od in tend ed on ly f or p rogram min g
equipment requires V
ID
on address pin A9 and OE#.
This method is compatible with programmer routines
written for earlier 3.0 volt-only AMD flash devices.
The device i s shi pped wit h all s ectors unprotecte d.
AMD offers the op tion of prog ramming and protectin g
sectors at its factory prior to shipping the device
through AMD’s Expr es sFlash™ Service. Contact an
AMD representative f or details.
It is possible to determine whether a sector is pro-
tected or unprotected. See the Secto r/Sector Block
Protect ion and Unprotection sec tion fo r details .
Write Protect (WP#)
The Write Protect function provides a hardware
method of protecti ng wit hout using V
ID
. This f unction is
one of two provided by the WP#/ACC pin.
If the sy stem a ssert s V
IL
on the WP#/ACC pin, the de-
vice disa bles pro gram and eras e fun cti ons i n se ctors
0, 1, 140, and 141, independen tly of whethe r those
sectors were protected or unprotected using the
method described in “Sector/Sector Block Protection
and Unprotection”.
If the sys tem asserts V
IH
on the WP#/ACC pin, the de-
vice reverts to whether sectors 0, 1, 140, and 141
were last set to be protected or unprotected. That is,
sector protection or unprotection for these sectors de-
pends on whether they were last protected or unpro-
tected using the method described in “Sector/Sector
Block Protection and Unprotection”.
Note that the WP#/ACC pin must not be left floating or
unconnected; inconsistent behavior of the device may
result.
Table 7. WP#/ACC Modes
Temporary Sector Unprotect
(Note: For the following discussion, the term “sector”
applies to both sectors and sector blocks. A sector
block consists of two or more adjacent sectors that are
protec ted or unp rotect ed at the same tim e (see Ta ble
6).
This feature allows temporary unprotection of previ-
ously protected sectors to change data in-s ystem. The
Sector Unprotect mode is ac tivated by setting the RE-
SET# pin to V
ID
. During this mode, formerly prot ected
sectors can be programmed or erased by selecting the
sector addresses. Once V
ID
is removed from the RE-
SET# pin, all the previously protected sectors are
protec ted a gain. Figure 1 shows the algorithm, and
Figure 25 sh ows the timing diagram s, for this feature.
If the WP#/ACC pin is at V
IL
, sectors 0, 1, 140, and
141 will r emain protected during the Temporary sector
Unprotect mode.
Figure 1. Temporary Sector Unprotect Operation
WP# Input
Voltage
Device
Mode
V
IL
Disables programming and erasing in
SA0, SA1, SA140, and SA141
V
IH
Enables programming and erasing in
SA0, SA1, SA140, and SA141
V
HH
Enables accelerated progamming (ACC).
See “Accelerated Program Operation” on
page 12.
START
Perfor m Erase or
Program Operations
RESET# = V
IH
Temporar y Sector
Unprotect Completed
(Note 2)
RESET# = V
ID
(Note 1)
Notes:
1. All protected sectors unprotected (If WP#/ACC = V
IL
,
sectors 0, 1, 140, and 141 will remain protected).
2. All previously protected sectors are protected once
again.