W25Q40BW_13 Datasheet, PDF (52/73 Pages) Winbond – 1.8V 4M-BIT SERIAL FLASH MEMORY WITH DUAL AND QUAD SPI

W25Q40BW
8.2.34 Read Unique ID Number (4Bh)
The Read Unique ID Number instruction accesses a factory-set read-only 64-bit number that is unique to
each W25Q40BW 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 32.
DO
24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 101 102 103
DO
*=MSB
*
63 62 61 60 59 2 1 0
Figure 32. Read Unique ID Number Instruction Sequence
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