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PCA9306: Level Translator related Queries

Part Number: PCA9306
Hello TI Team,
We have used PCA9306 Level Translator as per below Schematics:
I just want to understand that, what is the effect of 200k Resistor at the EN Pin?
There are few boards on which when I am connecting 100R resistor instead of 200K then only Level Translator works Correctly & we are getting the IMU Slave data Properly.
What this 200K Resistor cause & why is it Impacting on the Performance?
Note that Both sides of the Level Translator, Pull-ups are connected.
With Best Regards,
Saumil Shah

  • Hi Saumil,

    The EN and VREF2 ports are used for an internal bias circuit, and the external resistance is used to limit the current flowing into the device. It will still be functional with 100 kOhm, but we recommend 200 kOhm to more strongly limit current so that the device remains protected.

    Max
  • Hello Max,

    I understand this Logical Thing.

    My concern is that, what is the allowable Input Current for Enable Pin which is not given in the datasheet?

    Second thing is that My Slave devices are not giving Proper Communication with Master when there is 100K Resistor present. 

    When we are replacing 100K with 100 Ohms then It starts working.

    Please give the details on this scenario.

    Thanks

    Saumil

  • Hello Saumil,

    "My concern is that, what is the allowable Input Current for Enable Pin which is not given in the datasheet?"

    The enable pin is actually to a gate of a FET so you should think of this as a high impedance input. Vref1 and Vref2 can be low impedance and the absolute maximum current defined in the datasheet specifies 128mA.

    Questions about PCA9406 and the 200k resistor have been asked many times in the e2e forums, you can find it by searching either here or on google. This post for example gives more details on the enable/Vref2 and the 200k resistor.

    "Second thing is that My Slave devices are not giving Proper Communication with Master when there is 100K Resistor present. 

    When we are replacing 100K with 100 Ohms then It starts working."

    Can you provide a schematic around the PCA9306?

    What is the voltages at enable/Vref2 and Vref1?

    Voltages at SDA/SCL for both sides?

    Thanks,

    -Bobby