A d v a n c e I n f o r m a t i o n
Write the three-cycle Enter Secured Silicon Sector Region command se-
quence, and then follow the in-system sector protect algorithm as shown in
Figure 2, on page 36, except that RESET# may be at either V or V . This
IH
ID
allows in-system protection of the Secured Silicon Sector without raising any
device pin to a high voltage. Note that this method is only applicable to the
Secured Silicon Sector.
Write the three-cycle Enter Secured Silicon Sector Region command se-
quence, and then use the alternate method of sector protection described in
the Sector Group Protection and Unprotection on page 31 section.
Once the Secured Silicon Sector is programmed, locked and verified, the system
must write the Exit Secured Silicon Sector Region command sequence to return
to reading and writing within the remainder of the array.
Factory Locked: Secured Silicon Sector Programmed and
Protected At the Factory
In devices with an ESN, the Secured Silicon Sector is protected when the device
is shipped from the factory. The Secured Silicon Sector cannot be modified in any
way. An ESN Factory Locked device has an 16-byte random ESN at addresses
000000h–000007h. Please contact your sales representative for details on or-
dering ESN Factory Locked devices.
Customers may opt to have their code programmed by the factory through the
Spansion programming service (Customer Factory Locked). The devices are then
shipped from the factory with the Secured Silicon Sector permanently locked.
Contact your sales representative for details on using the Spansion program-
ming service.
Write Protect (WP#)
The Write Protect function provides a hardware method of protecting the first or
last sector group without using V . Write Protect is one of two functions pro-
ID
vided by the WP#/ACC input.
If the system asserts V on the WP#/ACC pin, the device disables program and
IL
erase functions in the first or last sector group independently of whether those
sector groups were protected or unprotected. Note that if WP#/ACC is at V
IL
when the device is in the standby mode, the maximum input load current is in-
creased. See the table in DC Characteristics on page 64.
If the system asserts V
on the WP#/ACC pin, the device reverts to
IH
whether the first or last sector was previously set to be protected or un-
protected using the method described in Sector Group Protection and
Unprotection on page 31. Note that WP# contains an internal pullup;
when unconnected, WP# is at V
.
IH
Hardware Data Protection
The command sequence requirement of unlock cycles for programming or eras-
ing provides data protection against inadvertent writes (refer to Table 30 on
page 54 and Table 31 on page 55 for command definitions). In addition, the fol-
lowing hardware data protection measures prevent accidental erasure or
programming, which might otherwise be caused by spurious system level signals
during V power-up and power-down transitions, or from system noise.
CC
Low V
Write Inhibit
CC
When V
is less than V
, the device does not accept any write cycles. This
CC
LKO
protects data during V power-up and power-down. The command register and
CC
38
S29GL-A MirrorBit™ Flash Family
S29GL-A_00_A3 April 22, 2005
SPANSION [ SPANSION ]
