What is the size of the EEPROM needed for the DS100DF410?

Answer: The size of the external EEPROM must be between 128 bytes and 1024 bytes. A single external EEPROM can be used by up to 16 DS100DF410 devices. The EEPROM can store the Retimer configuration in one of two ways:

1. Common channel configuration: All four channels in a given Retimer receive the same configuration. Different Retimers connected to the same EEPROM can still receive a different configuration, but all channels in that Retimer will be configured the same.
2. Unique channel configuration: Each of the four channels in a given Retimer can receive a unique configuration. Different Retimers connected to the same EEPROM can receive a different configuration.

The maximum number of unique Retimer configurations which can be stored in the largest supported EEPROM is 12 for common channel configuration and 3 for unique channel configuration.

In other words, if you wanted to take a conservative approach and ensure that each Retimer connected to the EEPROM could receive a unique configuration, then the size of the EEPROM selected should follow these guidelines:

• If using a common channel configuration, the EEPROM size should be at least 51 + N*77, where N is the number of Retimers sharing the EEPROM
• If using a unique channel configuration, the EEPROM size should be at least 51 + N*299, where N is the number of Retimers sharing the EEPROM

In no case should the size of the EEPROM excede 1024 bytes. Here are a few other requirements for the EEPROM:

1. The base SMBus write address of the external EEPROM must be 0xA0.
2. The external EEPROM must support paging by using the one or two LSBs of hte SMBus address as page bits.
3. The external EEPROM must support 2.5V to 3.3V SMBus I/O voltages.
4. The external EEPROM must support up to 400KHz SMBus clock speeds.

A family of EEPROMs that meets all of these requirements is the Atmel AT24C01/2/4/8B family.

Casey Morrison