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Original question:

TCA9517: SDA and SCL low-level input voltage contention B but how about A?

TCA9517: About datasheet interpretation VIL and VILC, System VS TCA9517 condition

Katsumi Takada
Prodigy 50 points
Part Number: TCA9517

Hi, team.Please follow datasheet interpretation.

Q1: If system device use  VOL=0.4V,
which of the datasheet TCA9517 side should

Look at:(Vccb=3.3)

VIL(=0.3*Vccb=0.99V(max))
or
VILC(=0.4V(typ))


Q2:I think VIL would be fine, but in what kind of situation should VILC be used.



  • 0
    Guru 316690 points

    The specified VIL value for SDAB/SCLB is explained in footnote (2), but it is meaningless for you. You need to use the lower value, which is always VILC.

  • 0
    TI__Mastermind 47328 points

    Hi Katsumi,

    Clemens is correct about the footnote. VIL for the B-side is the specification for the first low level seen by the SDAB and SCLB lines. VILC is for the second subsequent low levels seen by the SDAB and SCLB lines. 

    All devices connected on the B-side of the I2C bus should be able to drive an output low voltage level below the typical VILC spec (0.4V). VOLB = <0.4V for all devices. This spec must be adhered to so that the device can properly determine which side is driving a low-voltage signal in order to not lock the I2C bus. 

    TI specs the VIL = 30% of VCCB because this is the spec listed in the I2C standard. For this particular buffer, an additional requirement of VILC is needed for proper operation of the device. 

    Regards,

    Tyler

  • 0 in reply to Clemens Ladisch
    Prodigy 50 points

    Clemens-san, Thank you for oppinion.
    I must the VILC lower value. 
    Thank you so much
    Best Regards,
    katsumi

  • 0 in reply to Tyler Townsend
    Prodigy 50 points

    Tyler-san, Thank you for answer.
    B port of I2C bus is less than VILC0.4.
    All VOLB=<0.4V,
    and
    VIL = VCCB = 30%     I was able to understand that it is based on the I2C standard. 

    Thank you for the deteiled explanation.

    Best Regards,
    katsumi