• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 33 subscribers
  • Views 1008 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

PCA9306: leakage current protection

user4760726
Intellectual 1195 points
Part Number: PCA9306

Hi team, 

Does PCA9306 has leakage current  protection? please refer to the diagram below. Does SCL1 and SCL2 might have leakage problem if VREF1 is off and VDPU is on? if so, how to solve it? Please advised. 

  • 0
    TI__Guru 72161 points
    Hey user4760726,

    What you seeing is not leakage current flowing from side 2 to 1. From the device's perspective, side 1 looks like it is pulling low which causes side two to push current from side 2 to side 1. (Essentially the switch between side 1 and 2 is turned on)

    From the schematic I guess the voltage seen on side two is a voltage divider of Vref 1 pull up resistor and Vref 2 pull up resistor.
    [RVref1/(RVref1+ RVref2)] x 3.3V = VSCL2
    If the pull up values are the same then this voltage will be about 1.65V.
    If the pull up resistors are not the same values, then I suspect the maximum voltage the other side can see is approximately 2.7V (if 3.3V is the value you are using). The max value can move with Vref2.

    If this is causing problems with the application (I assume it is) then what we can do is tie Vref1 and EN pin together INSTEAD of Vref2. This solution will work as long as Vref2 is never GND when Vref1 is 1.8V otherwise the problem would repeat itself on the other side. If this solution is not plausible then we can tie the EN pin to a GPIO with a reference voltage either at GND or Vref1 (the lower voltage).

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    TI__Intellectual 1195 points
    Thanks for the well explanation. One follow-up question: what is SCL2/SDA2 state if EN is low?
  • 0 in reply to user4760726
    TI__Guru 72161 points

    Hey user4760726,

    "what is SCL2/SDA2 state if EN is low?"

    -You can expect this to be the pull up voltage on side 2 because EN low will turn the switches between side 1 and side 2 off. This is why I suggested you could place a GPIO on the EN in my previous post (make sure the reference voltage when turned on is Vref1 though).

    Thanks,

    -Bobby