JS28F512P30TFA datasheet(31/86 Pages) MICRON

31 / 86 page

Datasheet

Sept 2012

Order Number:208042-0

P30-65nm

10.0

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.

10.1

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 Section 8.6, “Program Protection” on

page 28 and Section 9.5, “Erase Protection” on page 30).

10.1.1

Lock Block

To lock a block, issue the Block Lock Setup command. The next command must be the

Block Lock command issued to the desired block’s address (see Section 6.2, “Device

Command Bus Cycles” on page 20 and Figure 35, “Block Lock Operations Flowchart” on

page 77). If the Configure Read Configuration 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 VPP. The block

lock bits may be modified and/or read even if VPP is at or below VPPLK.

10.1.2

Unlock Block

The Block Unlock command is used to unlock blocks (see Section 6.2, “Device

Command Bus Cycles” on page 20). Unlocked blocks can be read, programmed, and

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 Figure 9, “Block Locking State Diagram” on page 32).

10.1.3

Lock-Down Block

A locked or unlocked block can be locked-down by writing the Block Lock-Down

command sequence (see Section 6.2, “Device Command Bus Cycles” on page 20).

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 Block

Unlock command with WP# deasserted. To return an unlocked block to locked-down

state, a Block Lock-Down command must be issued prior to changing WP# to VIL.

Locked-down blocks revert to the locked state upon reset or power up the device (see

Figure 9, “Block Locking State Diagram” on page 32).

10.1.4

Block Lock Status

The Read Device Identifier command is used to determine a block’s lock status (see

Section 7.2, “Read Device Identifier” on page 22). Data bits DQ[1:0] display the

addressed block’s lock status; DQ0 is the addressed block’s lock bit, while DQ1 is the

addressed block’s lock-down bit.

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