AT88SC25616C

3

5017KJS–SMEM–08/09

Figure 2.

Block Diagram

Random

Generator

Authentication,

Encryption and

Certification Unit

EEPROM

Answer to Reset

Data Transfer

Password

Verification

Reset Block

Asynchronous

ISO Interface

Synchronous

Interface

Power

Management

GND

SCL/CLK

SDA/IO

RST

2.

Pin Descriptions

2.1.

2.2.

Clock (SCL/CLK)

In the asynchronous T = 0 protocol, the SCL/CLK input is used to provide the device with a carrier frequency f. The

nominal length of one bit emitted on I/O is defined as an “elementary time unit” (ETU) and is equal to 372/ f. When the

synchronous protocol is used, the SCL/CLK input is used to positive edge clock data into the device and negative edge

clock data out of the device.

2.3.

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 programmed 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.

2.4.

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 external pull-up resistor should be connected between SDA and VCC.

The value of this 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 average power. SDA/IO information applies to both asynchronous and

synchronous protocols.

When the synchronous protocol is used, the SCL/CLK input is used to positive edge clock data into the device and

negative edge clock data out of the device.