5277AS− CryptoCompanion −02/08

1.3.3. Environmental

CryptoCompanion is guaranteed to operate over the commercial temperature range of 0° to 70° C. ESD is rated at 3KV,

Human Body Model.

1.3.4. TWI Input/Output Operation

CryptoCompanion communicates to the system using a two wire interface (TWI), which is similar to SMBus. The chip

operates as a slave and does not support clock stretching. This two wire protocol is identical to that supported by the

Atmel AT24C16A serial EEPROM chips. Please see that datasheet on the Atmel web site for detailed timing and

protocol information.

The system processor is expected to properly format commands for CryptoCompanion (which may include information

from the CRF chip), and then process the outputs of CryptoCompanion (which may include sending some of the

outputs to the CRF chip).

CryptoCompanion cannot directly communicate with CRF chips. Both CRF and CryptoCompanion are slave devices.

The bus master may use one or two busses to communicate with them. Separate TWI addresses must be used if both

chips are on the same bus.

All communications packets sent to or from CryptoCompanion use the following naming conventions. The column

labeled “TWI name” provides the name of the byte as described in the AT24C16A datasheet.

2. AC & DC Characteristics (Preliminary)

Table 2.

DC Characteristics

Symbol

Parameter

Test Condition

Min

Typ

Max

Units

Supply Voltage

2.7

3.3

V

Icc

Supply Current

1MHz

5

mA

Standby Current

100

uA

SDA Input Low Voltage

0

V

CLK Input Low Voltage

0

V

RST Input Low Voltage

0

V

SDA Input High Voltage

V

SCL Input High Voltage

V

RST Input High Voltage

V

SDA Input Low Current

15

uA

SCL Input Low Current

15

uA

RST Input Low Current

50

uA

SDA Input High Current

20

uA

SCL Input High Current

100

uA

RST Input High Current

150

uA

SDA Output High Voltage

20K ohm external pull-up

V

SDA Output Low Voltage

0

V

SDA Output High Current

VOH

20

uA

4

CryptoCompanion

™ Chip