93AA46AE48 Datasheet, PDF (11/26 Pages) Microchip Technology – 1K Microwire Serial EEPROM with EUI-48™ Node Identity

93AA46AE48
3.0 PRE-PROGRAMMED EUI-48
NODE ADDRESS
The 93AA46AE48 is programmed at the factory with a
globally unique node address stored at the beginning of
the array. It is preceded by the EEPROM Programmed
Indicator (EPI), which indicates valid programming.
The 93AA46AE48 is designed to be compatible with
the following SMSC Ethernet controllers: LAN9210,
LAN9211, LAN9215, LAN9217, LAN9218, LAN9220,
and LAN9221. These controllers will automatically
detect and load the EUI-48 node address from the
93AA46AE48 at start-up.
3.1 EUI-48 Node Address
The 6-byte EUI-48 node address value of the
93AA46AE48 is stored in array locations 0x01 through
0x06, as shown in Figure 3-1. The first three bytes are
the Organizationally Unique Identifier (OUI) assigned
to Microchip by the IEEE Registration Authority. The
remaining three bytes are the Extension Identifier, and
are generated by Microchip to ensure a globally
unique, 48-bit value.
Note:
Currently, Microchip’s OUIs are
0x0004A3, 0x001EC0, 0xD88039 and
0x5410EC, though this will change as
addresses are exhausted.
3.1.1
EUI-64 SUPPORT USING THE
93AA46AE48
The pre-programmed EUI-48 node address of the
93AA46AE48 can easily be encapsulated at the
application level to form a globally unique, 64-bit node
address for systems utilizing the EUI-64 standard. This
is done by adding 0xFFFE between the OUI and the
Extension Identifier as shown below.
3.2 EEPROM Programmed Indicator
(EPI)
In addition to the node address, a programmed
indicator code is stored at the location 0x00. The code
is fixed as 0xA5. Its purpose is to let the master device
know that the EEPROM has been programmed with a
valid MAC address.
Note:
The pre-programmed values are not
write-protected and can be overwritten by
the user. Care must be taken not to
overwrite the values unintentionally.
FIGURE 3-1:
EUI-48 NODE ADDRESS PHYSICAL MEMORY MAP EXAMPLE
Description
24-bit Organizationally
EPI
Unique Identifier
24-bit Extension
Identifier
Data
Array
Address
A5h
00h
04h
A3h
12h
34h
56h
00h
01h
02h
03h
04h
05h
06h
Corresponding EUI-48^™ Node Address: 00-04-A3-12-34-56
Corresponding EUI-64^™ Node Address After Encapsulation: 00-04-A3-FF-FE-12-34-56
 2013-2016 Microchip Technology Inc.
DS20005229C-page 11