DS2703U+T&R Maxim Integrated Products, DS2703U+T&R Datasheet - Page 8

• Manufacturer Part Number: DS2703U+T&R
• Description: IC BATT AUTHENTICATE SHA-1 8UMAX
• Manufacturer: Maxim Integrated Products

Specifications of DS2703U+T&R

• Function: Battery Authentication
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SHA-1 related commands used while authenticating a battery or peripheral device are summarized in Table 3 for
convenience. Four additional commands for clearing, computing and locking of the Secret are described in detail in
the following section.
Table 3. Authentication Function Commands
Write Challenge
Compute MAC without ROM ID
and return MAC
Compute MAC with ROM ID and
return MAC
SECRET MANAGEMENT FUNCTION COMMANDS
LOAD SECRET [5Ah]. This command changes the 64-bit secret to the provided 64-bit data argument value. The
host must apply a programming pulse afterwards to copy the new secret value to EEPROM.
COMPUTE NEXT SECRET WITHOUT ROM ID [30h]. This command initiates a SHA-1 computation of the MAC
and uses a portion of the resulting MAC as the next or new secret. The MAC computation is performed with the
current 64-bit secret and the 64-bit challenge. The space in the message reserved for the ROM ID is filled with
logical 1's. Two words (64 bits) of the output MAC are used as the new secret value. The host must allow t
after issuing this command for the SHA calculation to complete, then apply a programming pulse to write the new
secret value to EEPROM.
COMPUTE NEXT SECRET WITH ROM ID [33h]. This command initiates a SHA-1 computation of the MAC and
uses a portion of the resulting MAC as the next or new secret. The MAC computation is performed with the current
64-bit secret, the 64-bit ROM ID, and the 64-bit challenge. Two words (64 bits) of the output MAC are used as the
new secret value. The host must allow t
apply a programming pulse to write the new secret value to EEPROM.
Note: Please contact the factory for details about what information is used to construct the new secret in the
Compute Next Secret With ROM ID and Compute Next Secret Without ROM ID commands.
LOCK SECRET [6Ah]. This command write protects the 64-bit Secret to prevent accidental or malicious overwrite
of the secret value. The Secret value stored in EEPROM becomes "final." The host must apply a programming
pulse to write the secret lock bit to EEPROM.
Table 4. Secret Loading Function Commands
Load Secret
Compute Next Secret without
ROM ID
Compute Next Secret with
ROM ID
Lock Secret
1-Wire SPEED CONTROL FUNCTION COMMANDS
CLEAR OVERDRIVE [8Dh]. This command clears the 1-Wire Overdrive bit to select the Standard 1-Wire timings
shown in the Electrical Characteristics table. The Overdrive bit is stored in EEPROM so that the programmed
speed selection can be recalled on initial power up. The host must apply a programming pulse to complete the
command.
COMMAND
COMMAND
HEX
5A
6A
30
33
HEX
0C
36
35
COMP
Loads the Secret with 64-bit data argument
Generates new global secret
Generates new unique secret
Sets lock bit to prevent changes to the Secret
Writes 64-bit challenge for SHA-1 processing. Required prior to
either Compute MAC command.
Computes hash with logical 1’s in place of the ROM_ID
Computes hash including the ROM_ID
after issuing this command for the SHA calculation to complete, then
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FUNCTION
FUNCTION
COMP