X25057
IDLock Operation
Operational Notes
Prior to any attempt to perform an IDLock Operation, the
WREN instruction must first be issued. This instruction
sets the “Write Enable” latch and allows the part to
respond to an IDLock sequence (Figure 7). The IDLock
instruction follows and consists of one command byte fol-
lowed by one IDLock byte (See Figure 1). This byte con-
tains the IDLock bits IDL2-IDL0. The rest of the bits [7:3]
are unused and must be written as zeroes. Bringing CS
HIGH after the two byte IDLock instruction initiates a
nonvolatile write to the Status Register. Writing more
than one byte to the Status Register will overwrite the
previously written IDLock byte. See Table 1.
The X25057 powers up in the following state:
• The device is in the low power, standby state.
• A HIGH to LOW transition on CS is required to enter
an active state and receive an instruction.
• SO pin is at high impedance.
• The “Write Enable” latch is reset.
Data Protection
The following circuitry has been included to prevent inad-
vertant writes:
• The “Write Enable” latch is reset upon power-up.
• A WREN instruction must be issued to set the “Write
Enable” latch.
• CS must come HIGH at the proper clock count in order
to start a write cycle.
Table 1. Instruction Set and Block Lock Protection Byte Definition
Instruction Format*
0000 0110
Instruction Name and Operation
WREN: Set the Write Enable Latch (Write Enable Operation)
WRDI: Reset the Write Enable Latch (Write Disable Operation)
0000 0100
0000 0001
IDLock Instruction—followed by:
IDLock Byte: (See Figure 1)
0000 0000 --->NO IDLock: 00h-00h ---------->None of the Array
0000 0001 --->IDLock Q1: 00h-7Fh ---------->Lower Quadrant (Q1)
0000 0010 --->IDLock Q2: 80h-FFh----------->Q2
0000 0011 --->IDLock Q3: 100h-17Fh-------->Q3
0000 0100 --->IDLock Q4: 180h-1FFh-------->Upper Quadrant (Q4)
0000 0101 --->IDLock H1: 00h-FFh----------->Lower Half of the Array (H1)
0000 0110 --->IDLock P0: 0h-Fh-------------->Lower Page (P0)
0000 0111 --->IDLock Pn: 1F0h-1FFh-------->Upper Page (Pn)
0000 0101
0000 0010
0000 0011
READ STATUS: Reads IDLock & write in progress status on SO Pin
WRITE: Write operation followed by address and data
READ: Read operation followed by address
7033 FRM T03
*Instructions are shown with MSB in leftmost position. Instructions are transferred MSB first.
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