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TCA9617B: Vil of TCA9617B

Lilian Chang
Intellectual 1555 points
Part Number: TCA9617B
Other Parts Discussed in Thread: TCA9517A

Hi Team,

I found the max Vil of TCA9617B is 0.4V in the datasheet? What do 0.3*VCCB / 0.3*VCCA mean?   

My customer connect TCA9617B B port output to another TCA9617B device B port as input.    B port to B port.  But the Vol of B port is 0.54V, what's the max VIL of B port at VCCB=3.3V?   

  • 0
    TI__Mastermind 49040 points

    Hey Lilian,

    Vol on B side of the TCA9617B has the voltage offset that most buffers do. This means if A pulls low, B side will be about 0.53V (this is B side's low). The B side VIL is a maximum value of 0.4V which means in order to propagate a low to A side, you need the master/slave device on B side to pull below 0.4V. This means A side of one device will not see low for A side of another device.

    From the information stated above, you cannot place B side to B side. This is also mentioned on page 9 of the datasheet in the overview section:

    The typical applications section 10.2.3 shows an example of the device being used in series where A is connected to B, which you may use as a reference.

    May I ask what voltages and frequency is expected of your system? Particularly why the TCA9617B was chosen.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Intellectual 1555 points
    Hi Bobby,

    There are two boards, each with TCA9617B on it, the problem is that there is a B side to B side connection.
    Do we have any recommended device can be used as a buffer , like B side to buffer to B side?
  • 0 in reply to Lilian Chang
    TI__Mastermind 49040 points

    Hey Lilian,

    Is there a reason why the customer cannot reverse the sides?(Does B side have a higher voltage than A side? Or did they already make the boards but now require a P2P solution?)

    "Do we have any recommended device can be used as a buffer , like B side to buffer to B side?"

    I need more information to make a recommendation. Information such as what voltages will be on A and B side as well as the frequency. If you can provide a block diagram or schematic of the current set up, I may be able to provide more help.

    Buffers we typically recommend are the TCA9517A and TCA980x. Both support up to 400kHz however the TCA980x family is recommended for 3.6V and under use and has a lower VOL. The TCA9517A allows for the VccB to be lower than VccA and viceversa, so you can swap the orientation like in your case.

    Thanks,

    -Bobby