m36w432b STMicroelectronics, m36w432b Datasheet - Page 17

• Manufacturer Part Number: m36w432b
• Description: 32 Mbit 2mb X16, Boot Block Flash Memory And 4 Mbit 256k X16 Sram, Multiple Memory Product
• Manufacturer: STMicroelectronics

Table 7. Program, Erase Times and Program/Erase Endurance Cycles
Flash Block Locking
The Flash Memory features an instant, individual
block locking scheme that allows any block to be
locked or unlocked with no latency. This locking
scheme has three levels of protection.
The locking status of each block can be set to
Locked, Unlocked, and Lock-Down. The following
sections explain the operation of the locking sys-
tem. Table 7, defines all of the possible locking
states (WP, DQ1, DQ0), and Appendix C, Figure
30, shows a flowchart for the locking operations.
Locked State. The default status of all blocks on
power-up or reset is Locked (states (0,0,1) or
(1,0,1)). Locked blocks are fully protected from
any program or erase. Any program or erase oper-
ations attempted on a locked block will return an
error in the Status Register. The Status of a
Locked block can be changed to Unlocked or
Lock-Down using the appropriate software com-
mands. An Unlocked block can be Locked by issu-
ing the Lock command.
Word Program
Double Word Program
Main Block Program
Parameter Block Program
Main Block Erase
Parameter Block Erase
Program/Erase Cycles (per Block)
Lock/Unlock - this first level allows software-
only control of block locking.
Lock-Down - this second level requires
hardware interaction before locking can be
changed.
V
hardware protection against program and erase
on all blocks.
PPF
V
PPLK
Parameter
- the third level offers a complete
Test Conditions
V
V
V
V
V
PPF
PPF
PPF
PPF
PPF
V
V
V
V
V
PPF
PPF
PPF
PPF
PPF
= 12V ±5%
= 12V ±5%
= 12V ±5%
= 12V ±5%
= 12V ±5%
= V
= V
= V
= V
= V
DDF
DDF
DDF
DDF
DDF
input pin. When WPF=0 (V
Lock-Down state (0,1,1) are protected from pro-
gram, erase and lock status changes. When
WPF=1 (V
(1,1,1) and Locked-Down blocks can be individu-
ally unlocked to the (1,1,0) state by issuing the
software command, where they can be erased and
programmed. These blocks can then be re-locked
(1,1,1) and unlocked (1,1,0) as desired while WPF
remains high. When WPF is low, blocks that were
previously Locked-Down return to the Lock-Down
state (0,1,1) regardless of any changes made
while WPF was high. Device reset or power-down
resets all blocks, including those in Lock-Down, to
the Locked state.
Unlocked State. Unlocked blocks (states (0,0,0),
(1,0,0) (1,1,0)), can be programmed or erased. All
unlocked blocks return to the Locked state when
the device is reset or powered-down. The status of
an unlocked block can be changed to Locked or
Locked-Down using the appropriate software
commands. A locked block can be unlocked by is-
suing the Unlock command.
Lock-Down State. Blocks that are Locked-Down
(state (0,1,1))are protected from program and
erase operations (as for Locked blocks) but their
Lock status cannot be changed using software
commands alone. A Locked or Unlocked block can
be Locked-Down by issuing the Lock-Down com-
mand. Locked-Down blocks revert to the Locked
state when the device is reset or powered-down.
The Lock-Down function is dependent on the WPF
100,000
IH
Min
) the Lock-Down function is disabled
Flash Memory
0.16
0.32
0.02
0.04
Typ
0.8
0.8
10
10
M36W432T, M36W432B
1
1
IL
), the blocks in the
Max
200
200
10
10
10
10
5
5
4
4
cycles
Unit
µs
µs
s
s
s
s
s
s
s
s
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