Datasheet

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16 Mbit LPC Serial Flash

SST49LF016C

Data Sheet

Microchip Technology Company

Write-Lock Bit

The Write-Lock bit, bit 0, controls the lock state described in Table 15. The default Write status of all

blocks after power up is write locked. When bit 0 of the Block Locking register is set, Program and

Erase operations for the corresponding block are prevented. Clearing the Write-Lock bit will unprotect

the block. The Write-Lock bit must be cleared prior to starting a Program or Erase operation since it is

sampled at the beginning of the operation. The Write-Lock bit functions in conjunction with the hard-

ware Write Lock pin TBL# for the top Boot Block. When TBL# is low, it overrides the software locking

scheme. The top Boot Block Locking register does not indicate the state of the TBL# pin. The Write-

Lock bit functions in conjunction with the hardware WP#/AAI pin for the remaining blocks (Blocks 0 to

33 for 49LF016C). When WP#/AAI is low, it overrides the software locking scheme. The Block Locking

Lock-Down Bit

The Lock-Down bit, bit 1, controls the Block Locking register as described in Table 15. When in LPC

interface mode, the default Lock Down status of all blocks upon power-up is not locked down. Once the

Lock-Down bit is set, any future attempted changes to that Block Locking register will be ignored. The

Lock-Down bit is only cleared upon a device reset with RST# or INIT# or power down. Current Lock

Down status of a particular block can be determined by reading the corresponding Lock-Down bit.

Once a block’s Lock-Down bit is set, the Read-Lock and Write-Lock bits for that block can no longer be

modified: the block is locked down in its current state of read/write accessibility.

Read-Lock Bit

The default read status of all blocks upon power-up is read-unlocked. When a block’s read lock bit is

set, data cannot be read from that block. An attempted read from a read-locked block will result in the

data 00h. The read lock status can be unlocked by clearing the read lock bit: this can only be done pro-

vided that the block is not locked down. The current read lock status of a particular block can be deter-

mined by reading the corresponding read-lock bit.

Table 15:Block Locking Register Bits

Reserved Bit

[7:3]

Read-Lock Bit

[2]

Lock-Down Bit

[1]

Write-Lock Bit

[0]

Lock Status

00000 0 0 0 Full Access

00000 0 0 1 Write Locked (Default State at Power-Up)

00000 0 1 0 Locked Open (Full Access Locked Down)

00000 0 1 1 Write Locked Down

00000 1 0 0 Block Read Locked (Registers alterable)

00000 1 0 1 Block Read & Write Lock (Registers alter-

able)

00000 1 1 0 Block Read Locked Down (Registers not

alterable)

00000 1 1 1 Block Read & Write lock Down (Registers

not alterable)

T15.0 25029