DS2460 Maxim, DS2460 Datasheet - Page 8

• Manufacturer Part Number: DS2460
• Description: The DS2460 SHA-1 Coprocessor with EEPROM is a hardware implementation of the ISO/IEC 10118-3 Secure Hash Algorithm (SHA-1), eliminating the need to develop software to perform the complex SHA computation required for authenticating SHA devices and fo
• Manufacturer: Maxim

Since a 885 pullup resistor, as would be required to meet the rise time specification at 400pF bus capacitance, is
lower than R
first calculating the minimum pullup resistor at any given operating voltage ("Minimum R
the respective bus capacitance that yields a rise time of 300ns.
Only for pullup voltages of 3V and lower can the maximum permissible bus capacitance of 400pF be maintained. A
reduced bus capacitance of 300pF is acceptable for pullup voltages of 4V and lower. For fast speed operation at
any pullup voltage, the bus capacitance must not exceed 200pF. The corresponding pullup resistor value at the
voltage is indicated by the "Minimum R
Figure 11. I²C Fast Speed Pullup Resistor Selection Chart
I²C Bus Compliance
Although the I²C protocol definition does not explicitly forbid a START - STOP - START sequence, the DS2460
does not tolerate it. If a START, STOP, START sequence has been issued, transmit the following sequence before
communicating with the DS2460: START, 10xxxxxx byte (x = don’t care bits), ACK/NACK bit, STOP.
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-“ in the package code
indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of
RoHS status.
PACKAGE TYPE
8 SO
PMIN
2000
1600
1200
800
400
at 5.5V, a different approach is necessary. The "Max. Load…" line in Figure 11 is generated by
0
1
PACKAGE CODE
S8+4
"Minimum Rp"
2
P
" line.
DOCUMENT NO.
Pull-up Voltage
21-0041
3
Max. Load at Min. Rp fast mode
8 of 9
4
5
P
" line) and then calculating
500
400
300
200
100
0