Datasheet
TUSB8040A
SLLSEA7F –MAY 2012–REVISED SEPTEMBER 2013
www.ti.com
3.3 SMBus Slave Operation
When the SMBus interface mode is enabled, the TUSB8040A supports read block and write block
protocols as a slave-only SMBus device.
The TUSB8040ARKM slave address is 1000 pgxy, where:
• p is the state of PORTINDz_SMBA3 at reset,
• g is the state of GANGED_SMBA2 at reset,
• x is the state of FULLPWRMGMTz_SMBA1 at reset, and
• y indicates read (logic 1) or write (logic 0) access.
If the TUSB8040A is addressed by a host using an unsupported protocol it will not respond. The
TUSB8040A will wait indefinitely for configuration by the SMBus host and will not connect on the upstream
port until the SMBus host indicates configuration is complete by clearing the CFG_ACTIVE bit.
For details on SMBus requirements refer to the System Management Bus Specification.
3.4 Configuration Registers
The internal configuration registers are accessed on byte boundaries. The configuration register values
are loaded with defaults but can be over-written when the TUSB8040A is in I
2
C or SMBus mode.
3.4.1 ROM Signature Register
Table 3-2. Register Offset 0h
Bit No. 7 6 5 4 3 2 1 0
Reset State 0 0 0 0 0 0 0 0
Table 3-3. Bit Descriptions – ROM Signature Register
Bit Field Name Access Description
ROM Signature Register. This register is used by the TUSB8040A in I
2
C
mode to validate the attached EEPROM has been programmed. The first
7:0 romSignature RW byte of the EEPROM is compared to the mask 55h and if not a match,
the TUSB8040A aborts the EEPROM load and executes with the register
defaults.
3.4.2 Vendor ID LSB Register
Table 3-4. Register Offset 1h
Bit No. 7 6 5 4 3 2 1 0
Reset State 0 1 0 1 0 0 0 1
Table 3-5. Bit Descriptions – Vendor ID LSB Register
Bit Field Name Access Description
Vendor ID LSB. Least significant byte of the unique vendor ID assigned
by the USB-IF; the default value of this register is 51h representing the
7:0 vendorIdLsb RW
LSB of the TI Vendor ID 0451h. The value may be over-written to
indicate a customer Vendor ID.
18 FUNCTIONAL DESCRIPTION Copyright © 2012–2013, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: TUSB8040A