Abridged Data Sheet

DS2460

7 of 8

Read and Write

This section discusses the read and write behavior of the various registers and the EEPROM. Please refer to the

full data sheet for details.

SHA-1 Engine Control

This section describes the user’s view of the SHA-1 engine and how to operate it. For details refer to the full data

sheet (includes Figures 7 to 9 and Tables 1 and 2).

SHA-1 COMPUTATION ALGORITHM

This description of the SHA computation is adapted from the Secure Hash Standard SHA-1 document that can be

version of the data sheet.

Application Information

SDA and SCL Pullup Resistors

SDA is an open-drain output on the DS2460 that requires a pullup resistor (Figure 10) to realize high logic levels.

Because the DS2460 uses SCL only as input (no clock stretching) the master can drive SCL either through an

open-drain/collector output with a pullup resistor or a push-pull output.

Figure 10. Application Schematic

SDA

SCL

µC

GND

SDA

AD0

SCL

AD1

AD2

GND

To additional

2-wire devices

Example

slave

address =

100 0101

condition determines the minimum value of the pullup resistor: R

of 5.5V, the minimum value for the pullup resistor is 1.7k

minimum pullup resistor changes with the operating (pull-up) voltage.

For I²C systems, the rise time and fall time are measured from 30% to 70% of the pullup voltage. The maximum

capacitance of 400pF the maximum pullup resistor would be 885

Ω.