MX28F640C3T Macronix International, MX28F640C3T Datasheet - Page 17

• Manufacturer Part Number: MX28F640C3T
• Description: 64M-BIT [4M x16] CMOS SINGLE VOLTAGE 3V ONLY FLASH MEMORY
• Manufacturer: Macronix International

4.9 Sector Lock/Unlock /Lock-down Command
4.9.1 Sector Locked State
The default status of all sectors when power-up or reset
is locked. Any attempt on program or erase operations
will result in an error on bit SR.1 of a locked sector. The
status of a locked sector can be changed to unlocked or
lock-down using software commands. An unlocked sec-
tor can be locked by writing the sector lock command
sequence, 60H followed by 01H.
4.9.2 Sector Unlocked State
An unlocked sector can be programmed or erased. All
unlocked sector return to the locked state when the de-
vice is either reset or powered down. The status of an
unlocked sector can be changed to locked or locked-
down using software commands. A locked sector can
be unlocked by writing unlock command sequence, 60H
followed by D0H.
4.9.3 Sector Locked-Down State
Sectors which are locked-down are protected from pro-
gram and erase operation; however, the protection sta-
tus of three sectors cannot be changed using software
commands alone. Any sector locked or unlocked can be
locked-down by writing the lock-down command se-
quence, 60H followed by 2FH. When the device is reset
or powered down, the locked-down sectors will revert to
the locked state.
The status of WP will determine the function of sector
lock-down and is summarized is followed:
P/N:PM0900
In addition, sector lock-down is cleared only when the
device is reset or powered down.
WP
WP=0
WP=1
Sector Lock-down Description
- sectors are protected from program, erase,
and lock status changes
- the sector lock-down function is disabled
- an individual lock-down sector can be un
locked and relocked via software command.
Once WP goes low, sectors that previously
locked-down returns to lock-down state
regardless of any changes when WP was
high.
17
4.9.4 Read Sector Lock Status
The lock status of every sector can be read through
Read Configuration mode. To enter this mode first com-
mand write 90H to the device. The next sector reads at
address +00002 will output the lock status of this sec-
tor. The lock status can be read from the lowest two
output pins Q0 and Q1. Q0, Q0 indicates the sector lock/
unlock status and set by the lock command and cleared
by the unlock command. When entering lock-down, the
lock status is automatically set. Q1 indicates lock-down
status and is set by the lock-down command. It cannot
be further cleared by software, only by device reset or
power-down.
Sector Lock Configuration Table
Lock Status
Sector is unlocked
Sector is locked
Sector is locked-down
MX28F640C3T/B
www.DataSheet4U.com
Q0=0
Q0=1
Q1=1
REV. 0.6, AUG. 20, 2003
Data