8 Write Sequence

To program the AT25010B/AT25020B/AT25040B, two separate instructions must be executed. First, the device must be write-enabled using the Write Enable (WREN) instruction. Then, one of the two possible write sequences described in this section may be executed.

Note: If the WP pin is driven low or the device is not write-enabled (WREN), the device will ignore the WRITE instruction and return to the standby state when CS is driven high. A new CS assertion is required to reinitiate communication.

The address of the memory location(s) to be programmed must be outside the protected address field location selected by the block write-protection level. During an internal write cycle, all commands except the RDSR instruction will be ignored. Refer to Table 8-1 for the address bits for AT25010B/AT25020B/AT25040B.

Table 8-1. AT25010B/AT25020B/AT25040B Address Bits
Address	AT25010B	AT25020B	AT25040B
A_N	A₆-A₀	A₇-A₀	A₈-A₀
Don’t Care Bits	A₇	None	None