DS125BR800 Datasheet, PDF (16/59 Pages) Texas Instruments – Low-Power 12.5-Gbps 8-Channel Repeater With Input Equalization and Output De-Emphasis

DS125BR800
SNLS426E – AUGUST 2012 – REVISED JANUARY 2015
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Programming (continued)
• Set the AD[3:0] inputs for SMBus address byte. When the AD[3:0] = 0000'b, the device address byte is 0xB0.
When tying multiple DS125BR800 devices to the SDA and SCL bus, use these guidelines to configure the
devices.
• Use SMBus AD[3:0] address bits so that each device can loaded it's configuration from the EEPROM.
Example below is for 4 device.
– U1: AD[3:0] = 0000 = 0xB0,
– U2: AD[3:0] = 0001 = 0xB2,
– U3: AD[3:0] = 0010 = 0xB4,
– U4: AD[3:0] = 0011 = 0xB6
• Use a pull-up resistor on SDA and SCL; value = 2 kΩ
• Daisy-chain READ_EN (pin 26) and ALL_DONE (pin 27) from one device to the next device in the sequence
so that they do not compete for the EEPROM at the same time.
1. Tie READ_EN of the 1st device in the chain (U1) to GND
2. Tie ALL_DONE of U1 to READ_EN of U2
3. Tie ALL_DONE of U2 to READ_EN of U3
4. Tie ALL_DONE of U3 to READ_EN of U4
5. Optional: Tie ALL_DONE output of U4 to a LED to show the devices have been loaded successfully
Below is an example of a 2 kbits (256 x 8-bit) EEPROM in hex format for the DS125BR800 device. The first 3
bytes of the EEPROM always contain a header common and necessary to control initialization of all devices
connected to the I2C bus. CRC enable flag to enable/disable CRC checking. If CRC checking is disabled, a fixed
pattern (8’hA5) is written/read instead of the CRC byte from the CRC location, to simplify the control. There is a
MAP bit to flag the presence of an address map that specifies the configuration data start in the EEPROM. If the
MAP bit is not present the configuration data start address is derived from the DS125BR800 address and the
configuration data size. A bit to indicate an EEPROM size > 256 bytes is necessary to properly address the
EEPROM. There are 37 bytes of data size for each DS125BR800 device. For additional information on EEPROM
programming, refer to SNLA228.
spacer
:2000000000001000000407002FAD4002FAD4002FAD4002FAD401805F5A8005F5A8005F5AD8
:200020008005F5A800005454000000000000000000000000000000000000000000000000F6
:20006000000000000000000000000000000000000000000000000000000000000000000080
:20008000000000000000000000000000000000000000000000000000000000000000000060
:2000A000000000000000000000000000000000000000000000000000000000000000000040
:2000C000000000000000000000000000000000000000000000000000000000000000000020
:2000E000000000000000000000000000000000000000000000000000000000000000000000
:200040000000000000000000000000000000000000000000000000000000000000000000A0
NOTE
The maximum EEPROM size supported is 8-kbits (1024 x 8 bits).
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