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XIO2001: GPIO Input transition time

takanobu fukuoka
Prodigy 70 points
Part Number: XIO2001

Hello,

The GPIO Input transition time (trise and tfall) is stated Max 25ns in Chapter 6.10 of the data sheet, but it doesn't satisfy the I2C-bus specification.
Is it okay to trust this value (Max. 25ns) when using EEPROM.

*: I2C-bus specification and user manual Rev. 6(p. 48)

symbol standard-mode Fast-mode Fast-mode Plus Unit
Min Max Min Max Min Max
rise time of both SDA and SCL signals - 1000 20 300 - 120 ns
fall time of both SDA and SCL signals - 300 20 300 20 120 ns

In summary:

What is the GPIO Input transition time value when using EEPROM (when using SDA and SCL)? 

Is it possible to connect the EEPROM that operates in Fast-mode? 

Best Regards,

T. Fukuoka

  • 0
    TI__Guru* 93670 points

    Greetings,

    Typical rise/fall time is 0nS. Therefor it means we can operate the part at faster rise/fall time than 25nS. If EEPROM rise/fall time is slower than 25ns - for example 30ns - then based on simulations and across temperature this does not meet device requirement. Please correct me if i mis-understood this question.

    Regards ,,Nasser

  • 0 in reply to Nasser Mohammadi
    Prodigy 70 points

    Hello Nasser,

    Thank you for your reply.

    If the above reply is correct, I think it is impossible to connect the I2C specification EEPROM and this IC. Because, I2C specification EEPROM rise / fall time is  300ns (Max.) in Fast-mode according to the following document.

    UM10204 I2C-bus specification and user manual (pololu.com)

    We will use the I2C specification EEPROM (S-24CS01AFJ-TB-G) that rise / fall time is 300ns (Max.). We are concerned that this EEPROM cannot be used.

    S24CS01A_02A_04A_08A_E4.5_00 (digikey.com)

    In summary:

    Please tell me know if I2C specification EEPROM can be used. 

    Best Regards,

    T. Fukuoka

  • 0 in reply to takanobu fukuoka
    Guru 316690 points

    The I²C specification allows for a 300 ns fall time because large buses have a large capacitance. This will not be the case for the short connection between the XIO and the EEPROM, so the fall time is likely to be below 25 ns.

    The I²C rise time depends on the pull-up resistance, and will always be larger than 25 ns. All the boards with XIO2001 out there work, so I guess the datasheet is wrong, at least for the I²C pins.