DS100BR111A_15 Datasheet, PDF (17/51 Pages) Texas Instruments – Ultra Low Power 10.3 Gbps 1-Lane Repeaters with Input Equalization and Output De-Emphasis

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DS100BR111A
SNLS400D – JANUARY 2012 – REVISED JANUARY 2015
8.5.5 Reading a Register
To read a register, the following protocol is used (see SMBus 2.0 specification):
1. The Host drives a START condition, the 7-bit SMBus address, and a “0” indicating a WRITE.
2. The Device (Slave) drives the ACK bit (“0”).
3. The Host drives the 8-bit Register Address.
4. The Device drives an ACK bit (“0”).
5. The Host drives a START condition.
6. The Host drives the 7-bit SMBus Address, and a “1” indicating a READ.
7. The Device drives an ACK bit “0”.
8. The Device drives the 8-bit data value (register contents).
9. The Host drives a NACK bit “1”indicating end of the READ transfer.
10. The Host drives a STOP condition.
Once the READ transaction is completed, the bus goes IDLE and communication with other SMBus devices may
now occur.
Please see Table 9 for more information.
8.5.6 EEPROM Programming
The DS100BR111A supports reading directly from an external EEPROM device by implementing SMBus Master
mode. When used in SMBus Master mode, the DS100BR111A will read directly from a specific location in the
external EEPROM. When designing a system that uses external EEPROM, the following guidelines should be
followed:
• Set the DS100BR111A in SMBus Master Mode.
– ENSMB (Pin 3) = Float
• The external EEPROM device must support 1 MHz operation.
• The external EEPROM device address byte must be 0xA0.
• Set the AD[3:0] inputs for SMBus address byte. When AD[3:0] = 0000'b, the device address byte is 0xB0.
• The device address can be set with the use of the AD[3:0] input up to 16 different addresses. Use the
example below to set each of the SMBus addresses.
– AD[3:0] = 0001'b, the device address byte is 0xB2
– AD[3:0] = 0010'b, the device address byte is 0xB4
– AD[3:0] = 0011'b, the device address byte is 0xB6
– AD[3:0] = 0100'b, the device address byte is 0xB8
• The master implementation in the DS100BR111A supports multiple devices reading from one EEPROM.
When tying multiple devices to the SDA and SCL pins, use these guidelines:
– Use adjacent SMBus addresses for the 4 devices
– Use a pull-up resistor on SDA; value = 4.7 kΩ
– Use a pull-up resistor on SCL: value = 4.7 kΩ
– Daisy-chain READEN (Pin 17) and DONE (Pin 18) from one device to the next device in the sequence.
1. Tie READEN of the 1st device in the chain (U1) to GND
2. Tie DONE of U1 to READEN of U2
3. Tie DONE of U2 to READEN of U3
4. Tie DONE of U3 to READEN of U4
5. Optional: Tie DONE of U4 to a LED to show each of the devices have been loaded successfully
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