Serial Number Read

Reading the 128-bit serial number is similar to the sequential read sequence but requires use of the device address seen in Figure 1, a dummy write and a specific word address. The word address must begin with a 10b sequence regardless of the intended address. If a word address other than 10b is used, the device will not output valid data.

Example: If the application desires to read the first byte of the serial number, the word address input would need to be 80h.

Note: The entire 128-bit value must be read from the starting address of the serial number block to ensure a unique number. Reading the serial number from a location other than the first address of the block will not result in a unique serial number.

When the end of the Security register is reached (32 bytes of data), the data word address will roll over to the beginning of Security register starting with the most significant byte of the 128-bit serial number. The serial number read operation or any read of the Security register is terminated when the master does not respond with an ACK and instead issues a Stop condition.

Figure 1. Serial Number Read

Notes:

1. For the AT24CSW04X, the @ indicates the A1 Address bit which is managed by the ordering code of the device (see Table 3). For the AT24CSW08X, the @ indicates the A9 address bit.
2. # indicates the hardware address value which is managed by the ordering code of the device (see Table 3 and Table 4).