X76F100

Characteristics subject to change without notice.

7 of 16

REV 1.0 6/22/00

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PASSWORDS

Passwords are changed by sending the “change read

password” or “change write password” commands in a

normal sector write operation. A full eight bytes con-

taining the new password must be sent, following suc-

cessful transmission of the current write password and

a valid password ACK response. The user can use a

repeated ACK Polling command to check that a new

password has been written correctly. An ACK indicates

that the new password is valid.

There is no way to read any of the passwords.

Response to Reset (Default = 19 00 AA 55)

The ISO Response to reset is controlled by the RST,

CS and CLK pins. When RST is pulsed high, while CS

is low, the device will output 32-bits of data, one bit per

clock. This conforms to the ISO standard for “synchro-

nous response to reset”. CS must remain LOW and the

part must not be in a write cycle for the response to

reset to occur.

After initiating a nonvolatile write cycle the RST pin

must not be pulsed until the nonvolatile write cycle is

complete. If not, the ISO response will not be acti-

vated. Also, any attempt to pulse the RST pin in the

middle of an ISO transaction will stop the transaction

with the SDA pin in high impedance. The user will have

to issue a stop condition and start the transaction

again. If at any time during the Response to Reset CS

goes HIGH, the response to reset will be aborted and

the part will return to the standby state. A Response to

Reset is not available during a nonvolatile write cycle.

Continued clocks after the 32-bits, will output the 32-bit

sequence again, starting at byte 0.

Figure 7. Response to RESET(RST)

CS

SCK

SO

RST

Byte

0

MSB

LSB

LSB

MSB

1

LSB

MSB LSB

MSB

2

3

1 0 0

0 0

1 1

1

0

0

0

0 0 0 0 0

0

0

0

0

1

1 0

1

1

1

0

0

0

1

1 0