PF38F5070M0P0B NUMONYX [Numonyx B.V], PF38F5070M0P0B Datasheet - Page 71

• Manufacturer Part Number: PF38F5070M0P0B
• Description: Numonyx Wireless Flash Memory (W18)
• Manufacturer: NUMONYX [Numonyx B.V]

Numonyx™ Wireless Flash Memory (W18)
13.0
13.1
November 2007
Order Number: 290701-18
Security Modes
The Numonyx Wireless Flash Memory (W18) offers both hardware and software
security features to protect the flash data. The software security feature is used by
executing the Lock Block command. The hardware security feature is used by executing
the Lock-Down Block command and by asserting the WP# signal.
Refer to
the flash security features. Also see
page
Block Lock Operations
Individual instant block locking protects code and data by allowing any block to be
locked or unlocked with no latency. This locking scheme offers two levels of protection.
The first allows software-only control of block locking (useful for frequently changed
data blocks), while the second requires hardware interaction before locking can be
changed (protects infrequently changed code blocks).
The following sections discuss the locking system operation. The term “state [abc]”
specifies locking states; for example, “state [001],” where a = WP# value, b = block
lock-down status bit
D1, and c = Block Lock Status Register bit D0.
Diagram” on page 72
The following summarizes the locking functionality.
Block lock registers are not affected by the V
even if V
Each block’s locking status can be set to locked, unlocked, and lock-down, as described
in the following sections. See
• All blocks power-up in a locked state.
• Unlock commands can unlock these blocks, and lock commands can lock them
• The Lock-Down command locks a block and prevents it from being unlocked when
again.
WP# is asserted.
— Locked-down blocks can be unlocked or locked with commands as long as WP#
— The lock-down status bit is cleared only when the device is reset or powered-
74.
is deasserted.
down.
Figure 31, “Block Locking State Diagram” on page 72
PP
≤
V
PPLK
.
defines possible locking states.
Figure 32, “Locking Operations Flowchart” on page
Figure 32, “Locking Operations Flowchart” on
PP
level. They may be modified and read
Figure 31, “Block Locking State
for a state diagram of
Datasheet
74.
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