W25X20BV WINBOND [Winbond], W25X20BV Datasheet - Page 35

• Manufacturer Part Number: W25X20BV
• Description: 1M-BIT, 2M-BIT AND 4M-BIT SERIAL FLASH MEMORY WITH 4KB SECTORS AND DUAL I/O SPI
• Manufacturer: WINBOND [Winbond]

9.2.22
The Read Unique ID Number instruction accesses a factory-set read-only 64-bit number that is unique
to each W25X10BV/20BV/40BV device. The ID number can be used in conjunction with user software
methods to help prevent copying or cloning of a system. The Read Unique ID instruction is initiated by
driving the /CS pin low and shifting the instruction code “4Bh” followed by a four bytes of dummy
clocks. After which, the 64-bit ID is shifted out on the falling edge of CLK as shown in figure 23.
DO
DO
DO
DO
*=MSB
*=MSB
Read Unique ID Number (4Bh)
24 25
24 25
26
26
27 28
27 28
Figure 23. Read Unique ID Number Instruction Sequence
29 30
29 30
31 32 33
31 32 33
34
34
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35 36
35 36
37 38
37 38
W25X10BV/20BV/40BV
Publication Release Date: August 20, 2009
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39
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*
40
40
63 62 61 60 59
63 62 61 60 59
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41
42 43 44 101 102 103
42 43 44 101 102 103
Preliminary -- Revision B
2
2
1
1
0
0