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TCA9509 - VIL requirement

Kawai
Guru 19785 points
Other Parts Discussed in Thread: TCA9509, TCA9517A

Hi Team,

Please allow me to ask you the requirement for TCA9509 to drive low from the external device (Master or Slave).

Regarding the datasheet specification below, V_IL of A-side is -0.5V to 0.3V. On the other hand, V_ILC = 0.15V(TYP). For the device to function correctly, I believe V_IL requires low level voltage lower than 0.15V (TYP) instead of 0.3V on A-side of the device.

Q1) Is my recognition correct ?

Q2) If correct, what is the V_IL description ? I think it should be -0.5V to 0.15V (TYP).

Q3) What is the maximum value of V_ILC ? Can we take as 0.15V ?

Q4) What is the target device to be connected to this device ? I believe most of the devices cannot support VOL(MAX) = 0.15V.

Best Regards,

Kawai

  • 0
    TI__Expert 5140 points
    Kawai-san,

    Your understanding is correct.

    The Vilc is a detection on the A-side to know when it has past a low or high threshold for that side while the VIL spec (for A & B) is used to determine what input low voltage level is needed.

    The VIL specification should remain the same as .15V is the typical value at which the low signal will be detected.

    We do not provide min/max because the difference of VOL - VILC will equal 0.5V which is the offset that is shown on the A - side of the device.

    Thanks,
  • 0 in reply to Siby James
    Guru 19785 points
    Hi Siby-san,

    Thank you for the answers. I understood that VIL (A-side) requires <= 0.15V. To guarantee the device to be operated normally, I believe this <=0.15V is the must requirement for this device. However, FPGA , MCU, and other major devices seems to have higher VOL(MAX). Can user use TCA9509 with such devices which has VOL higher than 0.15V ? What kind of devices is it supposed to be designed for ?

    Best Regards,
    Kawai
  • 0 in reply to Kawai
    TI__Expert 5140 points
    Kawai-san,

    The VOL specs for each respective side (A&B) are listed under a VOL spec. As long as the VOL of slave devices do not exceed these, then I see no issue with operation.

    Thanks,
    Siby
  • 0 in reply to Siby James
    Guru 19785 points

    Hello Siby-san,

    Please allow me to ask you in different question. Below is an example of ALTERA Arria V FPGA I/O spec.

    [Question]
    FPGA VOL(MAX)=0.2V is under TCA9509 VIL(MAX)=0.3V, however, over VILC=0.15V.
    If these devices are connected can you guarantee the device operation without any problem ?

    FPGA--------------->[A] TCA9509 [B]---------------->Device
    VOL(MAX)=0.2V

    * Customer needs to understand if their design could guarantee the device operation.

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Expert 5140 points
    Kawai-san,

    I understand the issue now. We CANNOT guarantee the device operation without any problem, because the VOL(MAX) of the FPGA will never allow the voltage to go lower than the VILC.

    Is there a possibility of using another I2C Buffer like TCA9517A?

    Thanks,
    Siby
  • 0 in reply to Siby James
    Guru 19785 points
    Hello Siby-san,

    Thank you for the answer.

    I was wondering that for which device TCA9509 designed for.
    It seems most of the devices can not guarantee VOL(MAX) lower than 0.15V. TI ADC, MCU devices also do not meet this spec.

    Best Regards,
    Kawai