X46402 Datasheet, PDF (9/23 Pages) Xicor Inc. – Dual Voltage CPU Supervisor with 64K Password Protected EEPROM

X46402
Preliminary Information
Figure 9. Definition of Start and Stop Conditions
Acknowledge
SCL
SDA
Start Condition
Stop Condition
Acknowledge is a software convention used to indicate
successful data transfer. The transmitting device, either
master or slave, will release the bus after transmitting
eight bits. During the ninth clock cycle the receiver will
pull the SDA line LOW to acknowledge that it received
the eight bits of data.
The X46402 will respond with an acknowledge after rec-
ognition of a start condition and its slave address. If both
the device and a write condition have been selected, the
X46402 will respond with an acknowledge after the
receipt of each subsequent eight-bit word.
Read Device ID Command
A special, non-password protected command reads the
device ID. The device ID is a 32 bit identification code
that can be generic or tailored to the needs of an individ-
ual company. The last of the 32 bits indicates whether
the device has been tampered with by an unauthorized
user attempting to enter invalid passwords.
Reset Device Command
The Reset Device command resets the tamper bit, clears
the tamper counter and removes the tamper “lock”
(allowing the device to accept commands). However, the
Reset Device command does not clear any memory
array area.
Table 3. X46402 Instruction Set
1st Byte
after Start
1st Byte
after
Password
2nd Byte
after
Password
Command Description
Password used
1000 0000 High Address Low address
Password Memory Array Read
Memory Read
1000 1000 High Address Low address
OTP Read
OTP Read
1001 0000 High Address Low address
Password Memory Array Write
Memory Write
1001 1000 High Address Low address
OTP Write
OTP Write
1010 0000 0000 0000 0000 0000
Change Memory Read Password
Memory Read
1010 1000 0000 0000 0000 0000
Change OTP Read Password
OTP Read
1011 0000 0000 0000 0000 0000
Change Memory Write Password
Memory Write
1011 1000 0000 0000 0000 0000
Change OTP Write Password
OTP Write
1100 0000 0000 0000 0000 0000
Change Reset Password
Reset
1100 1000 High Address Low address
No-Password Memory Array Read
None
1101 1000 High Address Low address
No-Password Memory Array Write
None
1110 1000 not used
not used
Reset Device Command (Resets Tamper bit)
Reset
1111 0000 not used
not used
ACK Polling command (Ends Password operation)
None
All the rest
Reserved
Notes: Illegal command codes will be disregarded. The part will respond with a “no-ACK” to the illegal byte and then return to the standby mode.
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