This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9617A: TCA9617 current leakage

Part Number: TCA9617A
Other Parts Discussed in Thread: TCA9617B

Hi 

Customer see when Vcca is 3.3v and Vccb is 0v, because the scla sdaa have a external pull high.

But they found scla and sdaa are 0.9v, sclb, sdab and en pin are 0v.

I see datasheet say that

due to ESD protection requirements on the SCLA and SDAA, it is required to power-up VCCB prior to VCCA. IF SDA and SCL (on A-side or B-side) are pulled up to a positive voltage before VCCB is powered, there can be significant current leakage into the SCA and SCL pins that could cause them to be pulled down. The SDA and SCL lines shall not be pulled up to a voltage higher than VCCB, even when the device is powered down

so is it the same case?

thanks.

  • Hey Kevin,

    I believe its the same as described in the datasheet, there is likely a path to GND through the ESD cell which looks like a large impedance and forms a voltage divider with the pull up resistor. You should always keep VccB larger than VccA when possible.

    Also we try to recommend customers use our TCA9617B rather than the TCA9617A as the B revision fixes some of the issues A has.

    Thanks,

    -Bobby

  • Hi Boddy,

    thanks, after checking b version, the description is remove.

    So when customer use b version, if b side is 0v like i mention before, is there any problem like a version?

  • Hey Kevin,

    My understanding of the transition from A version to B version has to do with with an issue with the high impedance modes of the drivers not activating properly when they should.

    "So when customer use b version, if b side is 0v like i mention before, is there any problem like a version?"

    B side is still required to be larger than A side for the device to work properly. But I suspect if the leakage current warnings of the ESD cells were removed from the datasheet then it is likely that the problem you previously saw should be gone but this is something I am not certain of.

    Thanks,

    -Bobby