DS100BR111 Datasheet, PDF (18/39 Pages) Texas Instruments – Ultra Low Power 10.3 Gbps 2-Channel Repeater with Input Equalization and Output De-Emphasis

The CRC-8 calculation is performed on the first 3 bytes of header information plus the 37 bytes of data for the DS100BR111 or 40
bytes in total. The result of this calculation is placed immediately after the DS100BR111 data in the EEPROM which ends with
"5454". The CRC-8 in the DS100BR111 uses a polynomial = x⁸ + x² + x + 1
In SMBus master mode the DS100BR111 reads its initial configuration from an external EEPROM upon power-up. Some of the
pins of the DS100BR111 perform the same functions in SMBus master and SMBus slave mode. Once the DS100BR111 has
finished reading its initial configuration from the external EEPROM in SMBus master mode it reverts to SMBus slave mode and
can be further configured by an external controller over the SMBus. The connection to an external SMBus master is optional and
can be omitted for applications were additional security is desirable. There are two pins that provide unique functions in SMBus
master mode.
• DONE#
• READEN#
When the DS100BR111 is powered up in SMBus master mode, it reads its configuration from the external EEPROM when the
READEN# pin goes low. When the DS100BR111 is finished reading its configuration from the external EEPROM, it drives the
DONE# pin low. In applications where there is more than one DS100BR111 on the same SMBus, bus contention can result if more
than one DS100BR111 tries to take control of the SMBus at the same time. The READEN# and DONE# pins prevent this bus
contention. The system should be designed so that the READEN# pin from one DS100BR111 in the system is driven low on power-
up. This DS100BR111 will take command of the SMBus on power-up and will read its initial configuration from the external
EEPROM. When it is finished reading its configuration, it will drive the DONE# pin low. This pin should be connected to the
READEN# pin of another DS100BR111. When this DS100BR111 senses its READEN# pin driven low, it will take command of the
SMBus and read its initial configuration from the external EEPROM, after which it will set its DONE# pin low. By connecting the
DONE# pin of each DS100BR111 to the READEN# pin of the next DS100BR111, each DS100BR111 can read its initial configu-
ration from the EEPROM without causing bus contention.
FIGURE 7. Typical multi-device EEPROM connection diagram
30138816
www.ti.com
18