DS125RT410_15 Datasheet, PDF (12/58 Pages) Texas Instruments – Low-Power Multi-Rate Quad Channel Retimer

DS125RT410
SNLS459A – APRIL 2013 – REVISED OCTOBER 2015
www.ti.com
Device Functional Modes (continued)
These pins are meant to work together. When the DS125RT410 is powered up in SMBus master mode, it reads
its configuration from the external EEPROM when the READ_EN pin goes low. When the DS125RT410 is
finished reading its configuration from the external EEPROM, it drives its ALL_DONE pin low. In applications
where there is more than one DS125RT410 on the same SMBus, bus contention can result if more than one
DS125RT410 tries to take command of the SMBus at the same time. The READ_EN and ALL_DONE pins
prevent this bus contention.
The system should be designed so that the READ_EN pin of one of the DS125RT410 devices in the system is
driven low on power-up. This DS125RT410 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 set its ALL_DONE
pin low. This pin should be connected to the READ_EN pin of another DS125RT410. When this DS125RT410
senses its READ_EN 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 ALL_DONE pin low. By connecting the ALL_DONE pin of each
DS125RT410 to the READ_EN pin of the next DS125RT410, each DS125RT410 can read its initial configuration
from the EEPROM without causing bus contention.
For SMBus slave mode, the READ_EN pin must be tied low. Do not leave the READ_EN pin floating or tie it
high.
A connection diagram with several DS125RT410 devices along with an external EEPROM and an external
SMBus master is listed in Figure 5. The SMBus master must be prevented from trying to take control of the
SMBus until the DS125RT410 devices have finished reading their initial configurations from the EEPROM.
From External
SMBus Master
SDA
SDC
EEPROM
DS125DF410
DS125DF410
One or both of these lines should
float for an EEPROM larger than
256 bytes
Set to unique
SMBus
address
Set to unique
SMBus
address
DS125DF410
DS125DF410
DS125DF410
Set to unique
SMBus
address
Set to unique
SMBus
address
Set to unique
SMBus
address
Figure 5. Connection Diagram for Multiple DS125RT410 Devices in SMBus Master Mode
12
Submit Documentation Feedback
Copyright © 2013–2015, Texas Instruments Incorporated
Product Folder Links: DS125RT410