X46402 Datasheet, PDF (13/23 Pages) Xicor Inc. – Dual Voltage CPU Supervisor with 64K Password Protected EEPROM

X46402
Preliminary Information
No-Password Sequential Read
The host can read sequentially within the un-protected
area of the array after receiving the No-password Com-
mand and an address within the unprotected address
space. 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 un-protected memory array contents
to be serially read during one operation. At the end of the
address space (address 1FFFh) the device goes into an
idle state and a new read sequence must be initiated to
continue reading at another address. Refer to Figure 16
for the address, acknowledge and data transfer
sequence. An acknowledge must follow each 8-bit data
transfer. After the last bit has been read, the host sends a
stop condition with or without a preceding acknowledge.
COMBINED RANDOM/SEQUENTIAL OPERATIONS
A random read and sequential read can be combined,
however there are some limitations. Both password pro-
tected or non-password operations operate in the same
way. After sending a random read command and reading
the first byte, continued clocks will return successive
addresses. However, after more than one byte of data is
returned, it is not possible to initiate a new random read,
without issuing a stop and starting a new command. This
also allows multiple random read operations and a
sequential read operation, as long as the last operation is
sequential. Note: A read operation that includes a
random read of the last byte in the memory or OTP
arrays cannot include a sequential read operation.
Figure 13. Password Protected Random Read
If ACK, then
Password Matches
SDA _S
Password
COMMAND
Read
Password
7
Read
Password
0
Wait t_WC
OR
Repeated
ACK Polling
Command
ACK POLLING
COMMAND
S
S
Data 0
S
Data 0
Figure 14. Password Protected Sequential Read
SDA _S
Password
COMMAND
Read
Password
7
If ACK, then
Password Matches
ACK POLLING
COMMAND
S
Read
Password
0
Wait t_WC
OR
Repeated
ACK Polling
Command
Data 0
S
Data X
13