X76F102

7

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 contain-

ing the new password must be sent, following successful

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 02 AA 55)

The ISO Response to reset is controlled by the RST and

CLK pins. When RST is pulsed high during a clock pulse,

the device will output 32 bits of data, one bit per clock,

and it resets to the standy state. This conforms to the ISO

standard for “synchronous response to reset”. 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 activated. If the RST

is pulsed HIGH and the CLK is within the RST pulse

it will output the 32 bit sequence again (starting at bit 0).

Otherwise, this aborts the ISO operation and the part

returns to standby state. If the RST is pulsed HIGH and

the CLK is outside the RST pulse (in the middle of an

ISO transaction), this aborts the ISO operation and the

part returns to standby state.

If there is power interrupted during the Response to

Reset, 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.

Figure 7. Response to RESET (RST)

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

1 0 0 0 0

0

0

0

0

1

1 0

1

1

1

0

0

0

1

1

0

ABSOLUTE MAXIMUM RATINGS*

Temperature under Bias ..................... –65°C to +135°C

Storage Temperature ..........................–65°C to +150°C

Voltage on any Pin with

D.C. Output Current..................................................5mA

Lead Temperature

(Soldering, 10 seconds).................................. 300°C

*COMMENT

Stresses above those listed under “Absolute Maximum

Ratings” may cause permanent damage to the device.

This is a stress rating only and the functional operation of

the device at these or any other conditions above those

listed in the operational sections of this specification is

not implied. Exposure to absolute maximum rating condi-

tions for extended periods may affect device reliability.