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X76F128 Datasheet, PDF (7/17 Pages) Xicor Inc. – Secure SerialFlash
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X76F128
READ OPERATIONS
Read operations are initiated in the same manner as write
operations but with a different command code.
Random Read
The master issues the start condition and a Read instruc-
tion and password, performs a Password Ack Polling, then
issues the word address. Once the password has been
acknowledged and first byte has been read, another start
can be issued followed by a new 8-bit address. Random
reads are allowed, but only the low order 8 bits can
change. This limits random reads to a 512 byte block.
Therefore, with a single password cycle only a 512 byte
block of array 0 may be accessed randomly. To randomly
access another block of array 0, a stop must be issued fol-
lowed by a new command/address/password sequence. A
random read of the array 1 can access all locations with-
out another password command sequence.
Figure 6. Random Read
SDA S
COMMAND
Read
Password
7
If ACK, then
Password Matches
Sequential Read
The host can read sequentially within an array after the
password acceptance sequence. The data output is
sequential, with the data from address n followed by the
data from n+1. The address counter for read operations
increments all address bits, allowing the entire memory
array contents to be serially read during one operation. At
the end of the address space (address 3FFFh for array 0,
3Fh for array 1), the counter “rolls over” to address 0 and
the X76F128 continues to output data for each acknowl-
edge received. Refer to figure 7 for the address, acknowl-
edge and data transfer sequence. An acknowledge must
follow each 8-bit data transfer. After the last bit has been
read, a stop condition is generated without a preceding
acknowledge.
Read
Password
0
Wait tWC
OR
Repeated
ACK Polling
Command
ACK POLLING
COMMAND
S
S
Data X
Data Y
S
7052 FM 11
Figure 7. Sequential Read
SDA S
COMMAND
If ACK, then
Password Matches
ACK POLLING
COMMAND
S
Read
Password
7
Read
Password
0
Wait tWC
OR
Repeated
ACK Polling
Command
Data 0
Data X
S
7052 FM 12
7
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