Datasheet

 2010 Microchip Technology Inc. DS22124D-page 13
24AA02E48/24AA025E48
9.0 PRE-PROGRAMMED EUI-48™
NODE ADDRESS
The 24AAXXXE48 is programmed at the factory with a
globally unique, EUI-48™ and EUI-64™ compatible
node address stored in the upper half of the array and
permanently write-protected. The remaining 1,024 bits
are available for application use.
FIGURE 9-1: MEMORY ORGANIZATION
The 6-byte EUI-48 node address value is stored in
array locations 0xFA through 0xFF, as shown in
Figure 9-2. The first 3 bytes are the Organizationally
Unique Identifier (OUI) assigned to Microchip by the
IEEE Registration Authority. Microchip’s OUI is
0x0004A3. The remaining 3 bytes are the Extension
Identifier, and are generated by Microchip to ensure a
globally-unique, 48-bit value.
9.1 EUI-64™ Support
The pre-programmed EUI-48 node address can easily
be encapsulated at the application level to form a glob-
ally 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.
FIGURE 9-2: EUI-48 NODE ADDRESS PHYSICAL MEMORY MAP EXAMPLE
00h
80h
FFh
Write-Protected
EUI-
48™ Block
Standard
EEPROM
FAh FFh
24-bit Organizationally
Unique Identifier
24-bit Extension
Identifier
00h 04h A3h 12h 34h 56h
Corresponding EUI-48™ Node Address: 00-04-A3-12-34-56
Description
Data
Array
Address
Corresponding EUI-64™ Node Address: 00-04-A3-FF-FE-12-34-56