DS110RT410 Datasheet, PDF (16/40 Pages) Texas Instruments – DS110RT410 Low Power Multi-Rate Quad Channel Retimer

DS110RT410
SNLS460 – MAY 2013
DEVICE CONFIGURATION MODES
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The DS110RT410 can be configured using two different methods.
• SMBus Master Configuration Mode
• SMBus Slave Configuration Mode
The configuration mode is selected by the state of the SMBus Enable pin (pin 20) when the DS110RT410 is
powered-up. This pin should be either left floating or tied to the device V_DD through an optional 1KΩ resistor. The
effect of each of these settings is shown in Table 3.
Pin Setting
Float
High (1)
Table 3. SMBus Enable Settings
Configuration Mode
SMBus Master Mode
SMBus Slave Mode
Description
Device reads its configuration from an
external EEPROM on power-up
Device is configured over the SMBus by an
external controller
SMBus Master Mode and SMBus Slave Mode
In SMBus master mode the DS110RT410 reads its initial configuration from an external EEPROM upon power-
up. A description of the operation of this mode appears in a separate application note.
Some of the pins of the DS110RT410 perform the same functions in SMBus master and SMBus slave mode.
Once the DS110RT410 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.
There are two pins that provide unique functions in SMBus master mode. These are as follows:
• ALL_DONE
• READ_EN
These pins are meant to work together. When the DS110RT410 is powered up in SMBus master mode, it reads
its configuration from the external EEPROM when the READ_EN pin goes low. When the DS110RT410 finish
reading its configuration from the external EEPROM, it drives its ALL_DONE pin low. In this mode, as the name
suggests, the DS100DF410 acts as an SMBus master during the time it is reading its configuration from the
external EEPROM. After the DS110RT410 has finished reading its configuration from the EEPROM, it releases
control of the SMBus and becomes a SMBus slave. In applications where there is more than one DS110RT410
on the same SMBus, bus contention can result if more than one device 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 the first device in the system is driven low on
power-up. This first DS110RT410 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 DS110RT410. When this DS110RT410
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
DS110RT410 to the READ_EN pin of the next DS110RT410, each DS110RT410 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 it floating or tie it high.
A connection diagram showing several DS110RT410s along with an external EEPROM and an external SMBus
master is shown in Figure 3 below. The SMBus master must be prevented from trying to take control of the
SMBus until the DS110RT410s have finished reading their initial configurations from the EEPROM.
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