Detailed Description
The MAX66140 combines 1024 bits of user EEPROM,
128 bits of user and control registers, a 64-bit UID, one
64-bit secret, a 512-bit SHA-1 engine, and a 13.56MHz
ISO 15693 RF interface in a single chip. The memory is
organized as 19 blocks of 8 bytes each. Except for the
secret, each block has a user-readable write-cycle
counter. Four adjacent user EEPROM blocks form a
memory page (pages 0 to 3). Memory protection fea-
tures include write protection and EPROM emulation,
which the user can set for each individual memory
page. Page 3 can also be read protected for enhanced
authentication strength. The MAX66140 is accessed
through ISO 15693-compliant memory and control func-
tion commands. The data rate can be as high as
26.69kbps. The MAX66140 supports AFI and DSFID.
Applications of the MAX66140 include driver identifica-
tion (fleet application), access control, electronic cash,
and asset tracking.
Overview
Figure 1 shows the relationships between the major con-
trol and memory sections of the MAX66140. The device
has six main data components: 1) 64-bit UID, 2) 64-bit
read/write buffer, 3) four 256-bit pages of user EEPROM,
4) two 8-byte blocks of user and control registers, 5) 64-
bit secret’s memory, and 6) a 512-bit SHA-1 engine.
Figure 2 shows the applicable ISO 15693 commands
and their purpose. The network function commands
allow the master to identify all slaves in its range and to
change their state, e.g., to select one for further commu-
nication. The protocol required for these network func-
tion commands is described in the
Network Function
Commands
section. The memory and control functions
access the memory of the MAX66140 for reading and
writing. The protocol for these memory and control func-
tion commands is described in the
Memory and Control
Function Commands
section. All data is read and writ-
ten least significant bit (LSb) first, starting with the least
significant byte (LSB).
Parasite Power
As a wireless device, the MAX66140 is not connected
to any power source. It gets the energy for operation
from the surrounding RF field, which needs to have a
minimum strength as specified in the
Electrical
Characteristics
table.
Unique Identification Number (UID)
Each MAX66140 contains a factory-programmed and
locked identification number that is 64 bits long
(Figure 3). The lower 36 bits are the serial number of the
chip. The next 8 bits store the device feature code, which
is 03h. Bits 45 to 48 are 0h. The code in bit locations 49 to
56 identifies the chip manufacturer, according to ISO/IEC
7816-6/AM1. This code is 2Bh for Maxim. The code in the
upper 8 bits is E0h. The UID is read accessible through
the Inventory and Get System Information commands.
MAX66140
