AT25DF021-MH-T Atmel, AT25DF021-MH-T Datasheet - Page 20

• Manufacturer Part Number: AT25DF021-MH-T
• Description: IC FLASH 2MBIT 70MHZ 8UDFN
• Manufacturer: Atmel

Specifications of AT25DF021-MH-T

• Format - Memory: FLASH
• Memory Type: DataFLASH
• Memory Size: 2M (256K x 8)
• Speed: 70MHz
• Interface: SPI, 3-Wire Serial
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-UDFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

location of the OTP Security Register to begin programming at. Since the size of the user-pro-
grammable portion of the OTP Security Register is 64 bytes, the upper order address bits do not
need to be decoded by the device. Therefore, address bits A23-A6 will be ignored by the device
and their values can be either a logical “1” or “0”. After the address bytes have been clocked in,
data can then be clocked into the device and will be stored in the internal buffer.
If the starting memory address denoted by A23-A0 does not start at the beginning of the OTP
Security Register memory space (A5-A0 are not all 0), then special circumstances regarding
which OTP Security Register locations to be programmed will apply. In this situation, any data
that is sent to the device that goes beyond the end of the 64-byte user-programmable space will
wrap around back to the beginning of the OTP Security Register. For example, if the starting
address denoted by A23-A0 is 00003Eh, and three bytes of data are sent to the device, then the
first two bytes of data will be programmed at OTP Security Register addresses 00003Eh and
00003Fh while the last byte of data will be programmed at address 000000h. The remaining
bytes in the OTP Security Register (addresses 000001h through 00003Dh) will not be pro-
grammed and will remain in the erased state (FFh). In addition, if more than 64 bytes of data are
sent to the device, then only the last 64 bytes sent will be latched into the internal buffer.
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
time to determine if the data bytes have finished
OTPP
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.
AT25DF021
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3677D–DFLASH–04/09