AT88SC153-10SU-00 Atmel, AT88SC153-10SU-00 Datasheet - Page 9

• Manufacturer Part Number: AT88SC153-10SU-00
• Description: IC EEPROM 2KBIT 1MHZ 8SOIC
• Manufacturer: Atmel
• Series: CryptoMemory®r

Specifications of AT88SC153-10SU-00

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 2K (256 x 8)
• Speed: 1MHz
• Interface: Serial
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7. User Zones
8. Security Operations
8.1
8.2
1016E–SMEM–12/07
Write Lock
Password Verification
Three zones are dedicated to the user data. The access rights of each zone are programmable
separately via the access registers. If several zones share the same password set, this set will
be entered only once (after the part is powered up), so several zones might be combined in one
larger zone.
If a user zone is configured in the write lock mode (access register bit 2), the lowest address
byte of a page constitutes a write access byte for the bytes of that page.
Table 8-1.
Example: The write lock byte (WLB) at $00 controls the bytes from $00 to $07.
The WLB can also lock itself by writing its least significant (right most) bit to “0”. The WLB can
only be programmed, i.e., bits written to “0” cannot return to “1”.
In the write lock configuration, only one byte of the page can be written at a time. Even if several
bytes are received, only the first byte will be taken into account by the device.
Compare the operation password presented with the stored one, and write a new bit in the corre-
sponding attempts counter for each wrong attempt. A valid attempt erases the attempts counter
and allows the operation to be carried out as long as the chip is powered.
The current password is memorized and active until power is turned off, unless a new password
is presented or RST becomes active. Only one password is active at a time. The AT88SC153
requires that the Verify Password command be transmitted twice in sequence to successfully
verify a write or read password. (This two-pass method of password verification was imple-
mented in the AT88SC153 to protect the device from attacks on the password security system.)
The first Verify Password command can be considered an initialization command. It will write a
new bit (“0”) in the corresponding PAC. The data bits in this initialization command are ignored.
The second Verify Password command will compare the 3-byte password data presented with
the corresponding password value stored in memory. If the comparison is valid, the PAC will be
cleared. A successful password verification will allow authorized operations to be carried out as
long as the chip is powered. The current password is memorized and active until power is turned
off, a new password is presented, or RST becomes active. Only one password is active at a
time. If a new user zone is selected that points to a different password set, the new password
must be verified and the old password becomes invalid.
11011001
$0 - WLB
Write Lock
Lock
x x
$1
Lock
x x
$2
x x
$3
x x
$4
Lock
x x
$5
x x
$6
x x
$7
$00
@
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