Datasheet

Hi-Speed USB 2.0 to 10/100/1000 Ethernet Controller
Datasheet
SMSC LAN7500/LAN7500i 19 Revision 1.0 (11-01-10)
DATASHEET
Chapter 3 EEPROM Controller (EPC)
LAN7500/LAN7500i may use an external EEPROM to store the default values for the USB descriptors
and the MAC address. The EEPROM controller supports most “93C56 or 93C66” type 256/512 byte
EEPROMs. A total of nine address bits are used for connection to the device.
Note: A 3-wire style 2K/4K EEPROM that is organized for 256/512 x 8-bit operation must be used.
The MAC address is used as the default Ethernet MAC address and is loaded into the device’s MAC
address registers. If a properly configured EEPROM is not detected, it is the responsibility of the Host
LAN Driver to set the IEEE addresses.
After a system-level reset occurs, the device will load the default values from a properly configured
EEPROM. The device will not accept USB transactions from the Host until this process is completed.
The device’s EEPROM controller also allows the Host system to read, write and erase the contents of
the Serial EEPROM.
3.1 EEPROM Format
Table 3.1 illustrates the format in which data is stored inside of the EEPROM.
Note the EEPROM offsets are given in units of 16-bit word offsets. A length field with a value of zero
indicates that the field does not exist in the EEPROM. The device will use the field’s HW default value
in this case.
Note: For the device descriptor, the only valid values for the length are 0 and 18.
Note: For the configuration and interface descriptor, the only valid values for the length are 0 and 18.
Note: The EEPROM programmer must ensure that if a string descriptor does not exist in the
EEPROM, the referencing descriptor must contain 00h for the respective string index field.
Note: If all string descriptor lengths are zero, then a Language ID will not be supported.
Table 3.1 EEPROM Format
EEPROM ADDRESS EEPROM CONTENTS
00h A5h (EEPROM Programmed Indicator)
01h MAC Address [7:0]
02h MAC Address [15:8]
03h MAC Address [23:16]
04h MAC Address [31:24]
05h MAC Address [39:32]
06h MAC Address [47:40]
07h Full-Speed Polling Interval for Interrupt Endpoint
08h Hi-Speed Polling Interval for Interrupt Endpoint
09h Configuration Flags 0
0Ah Language ID Descriptor [7:0]