RC28F256 Intel Corporation, RC28F256 Datasheet - Page 69

• Manufacturer Part Number: RC28F256
• Description: Intel StrataFlash Embedded Memory
• Manufacturer: Intel Corporation

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13.0
13.1
13.1.1
13.1.2
13.1.3
Datasheet
Security Modes
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, V
(see
page
The P30 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
and
Register command is issued after the Block Lock Setup command, the device configures the RCR
instead.
Block lock and unlock operations are not affected by the voltage level on V
may be modified and/or read even if V
Unlock Block
The Unlock Block command is used to unlock blocks (see
page
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
page
Lock-Down Block
A locked or unlocked block can be locked-down by writing the Lock-Down Block command
sequence (see
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-
Figure 46, “Block Lock Operations Flowchart” on page
Section 11.6, “Program Protection” on page 66
68).
50). Unlocked blocks can be read, programmed, and erased. Unlocked blocks return to a
70).
Section 9.2, “Device Commands” on page
Intel StrataFlash
Order Number: 306666, Revision: 001
PP
data security can be used to inhibit program and erase operations
®
Embedded Memory (P30)
PP
is at or below V
Figure 32, “Block Locking State Diagram” on
Section 9.2, “Device Commands” on page 50
and
Section 12.4, “Erase Protection” on
50). Blocks in a lock-down state cannot
PPLK
Section 9.2, “Device Commands” on
91). If the Set Read Configuration
.
PP
. The block lock bits
1-Gbit P30 Family
April 2005
69