Determining the Lock State of the Security Register

The Lock state of the device can be determined by sending a subset of the Lock command to the device. Only the device address byte and word address byte need to be transmitted to the device to determine the Lock state. An ACK response to the word address byte indicates the Lock has not been set while a NACK response indicates the Lock has been set. If the Lock has already been set, it cannot be undone. The abbreviated Lock sequence is completed by the master sending a Stop condition to the device.

Figure 1. Determining the Security Register Lock State

Notes:

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