AT25BCM512B_12 Datasheet, PDF (15/34 Pages) List of Unclassifed Manufacturers – 512-Kilobit 2.7-volt Minimum SPI Serial Flash Memory

AT25BCM512B [Preliminary]
When the CS pin is deasserted, the device will take the data stored in the internal buffer and pro-
gram it into the appropriate OTP Security Register locations based on the starting address
specified by A23-A0 and the number of data bytes sent to the device. If less than 64 bytes of
data were sent to the device, then the remaining bytes within the OTP Security Register will not
be programmed and will remain in the erased state (FFh). The programming of the data bytes is
internally self-timed and should take place in a time of t_OTPP.
The three address bytes and at least one complete byte of data must be clocked into the device
before the CS pin is deasserted, and the CS pin must be deasserted on even byte boundaries
(multiples of eight bits); otherwise, the device will abort the operation and the user-programma-
ble portion of the OTP Security Register will not be programmed. The WEL bit in the Status
Register will be reset back to the logical “0” state if the OTP Security Register program cycle
aborts due to an incomplete address being sent, an incomplete byte of data being sent, the CS
pin being deasserted on uneven byte boundaries, or because the user-programmable portion of
the OTP Security Register was previously programmed.
While the device is programming the OTP Security Register, the Status Register can be read
and will indicate that the device is busy. For faster throughput, it is recommended that the Status
Register be polled rather than waiting the t_OTPP time to determine if the data bytes have finished
programming. At some point before the OTP Security Register programming completes, the
WEL bit in the Status Register will be reset back to the logical “0” state.
If the device is powered-down during the OTP Security Register program cycle, then the con-
tents of the 64-byte user programmable portion of the OTP Security Register cannot be
guaranteed and cannot be programmed again.
The Program OTP Security Register command utilizes the internal 256-buffer for processing.
Therefore, the contents of the buffer will be altered from its previous state when this command is
issued.
Figure 10-1. Program OTP Security Register
CS
SCK
SI
SO
0123456789
29 30 31 32 33 34 35 36 37 38 39
OPCODE
ADDRESS BITS A23-A0
DATA IN BYTE 1
1 0 0 1 1 0 1 1AAA
MSB
MSB
AAADDDDDDDD
MSB
HIGH-IMPEDANCE
DATA IN BYTE n
DDDDDDDD
MSB
15
3704BX–DFLASH–11/2012