RC28F256P33TF Numonyx, RC28F256P33TF Datasheet - Page 30

• Manufacturer Part Number: RC28F256P33TF
• Description: 256-mbit, 512-mbit 256m/256m
• Manufacturer: Numonyx

10.0
10.1
10.1.1
10.1.2
10.1.3
Datasheet
30
Security
The device features security modes used to protect the information stored in the flash
memory array. The following sections describe each security mode in detail.
Block Locking
Individual instant block locking is used to protect user code and/or data within the flash
memory array. All blocks power up in a locked state to protect array data from being
altered during power transitions. Any block can be locked or unlocked with no latency.
Locked blocks cannot be programmed or erased; they can only be read.
Software-controlled security is implemented using the Block Lock and Block Unlock
commands. Hardware-controlled security can be implemented using the Block Lock-
Down command along with asserting WP#. Also, VPP data security can be used to
inhibit program and erase operations (see
page 27
The P33-65nm device also offers four pre-defined areas in the main array that can be
configured as One-Time Programmable (OTP) for the highest level of security. These
include the four 32 KB parameter blocks together as one and the three adjacent 128 KB
main blocks. This is available for top or bottom parameter devices.
Lock Block
To lock a block, issue the Lock Block Setup command. The next command must be the
Lock Block command issued to the desired block’s address (see
Command Bus Cycles” on page 18
page
Lock Setup command, the device configures the RCR instead.
Block lock and unlock operations are not affected by the voltage level on VPP. The block
lock bits may be modified and/or read even if VPP is at or below V
Unlock Block
The Unlock Block command is used to unlock blocks (see
Command Bus Cycles” on page
erased. Unlocked blocks return to a locked state when the device is reset or powered
down. If a block is in a lock-down state, WP# must be deasserted before it can be
unlocked (see
Lock-Down Block
A locked or unlocked block can be locked-down by writing the Lock-Down Block
command sequence (see
Blocks in a lock-down state cannot be programmed or erased; they can only be read.
However, unlike locked blocks, their locked state cannot be changed by software
commands alone. A locked-down block can only be unlocked by issuing the Unlock
Block command with WP# deasserted. To return an unlocked block to locked-down
state, a Lock-Down command must be issued prior to changing WP# to V
down blocks revert to the locked state upon reset or power up the device (see
“Block Locking State Diagram” on page
77). If the Set Read Configuration Register command is issued after the Block
and
Section 9.5, “Erase Protection” on page
Figure 8, “Block Locking State Diagram” on page
Section 6.2, “Device Command Bus Cycles” on page
18). Unlocked blocks can be read, programmed, and
and
Figure 38, “Block Lock Operations Flowchart” on
31).
Section 8.6, “Program Protection” on
29).
Section 6.2, “Device
31).
Section 6.2, “Device
PPLK
Order Number: 320003-05
.
IL
. Locked-
Figure 8,
P33-65nm
18).
Nov 2008