3

AT88SC25616C

5017DS–SMEM–7/04

Serial Data (SDA/IO)

The SDA pin is bidirectional for serial data transfer. This pin is open-drain driven and

may be wired with any number of other open drain or open collector devices. An exter-

nal pull-up resistor should be connected between SDA and V

resistor and the system capacitance loading the SDA bus will determine the rise time of

SDA. This rise time will determine the maximum frequency during read operations. Low

value pull-up resistors will allow higher frequency operations while drawing higher aver-

age power supply current.

Reset (RST)

The AT88SC25616C provides an ISO 7816-3 compliant asynchronous answer to reset

sequence. When the reset sequence is activated, the device will output the data pro-

grammed into the 64-bit answer-to-reset register. An internal pull-up on the RST input

pad allows the device to be used in synchronous mode without bonding RST. The

AT88SC25616C does not support the synchronous answer-to-reset sequence.

Device Architecture

User Zones

The EEPROM user memory is divided into 16 zones of 16,384 bits each. Multiple zones

allow for different types of data or files to be stored in different zones. Access to the user

zones is allowed only after security requirements have been met. These security

requirements are defined by the user during the personalization of the device in the con-

figuration zone. If the same security requirements are selected for multiple zones, then

these zones may effectively be accessed as one larger zone.

Control Logic

Access to the user zones occurs only through the control logic built into the device. This

logic is configurable through access registers, key registers and keys programmed into

the configuration zone during device personalization. Also implemented in the control

logic is a cryptographic engine for performing the various higher-level security functions

of the device.

Table 2. User Zones

ZONE

$0

$1

$2

$3

$4

$5

$6

$7

User 0

$000

2048 bytes

–

–

$7F8

User 1

-

-

-

User 14

$000

–

–

–

$7F8

User 15

$000

2048 bytes

–

–

$7F8