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TCA9802: TCA9802 leakage current problem

weilun luo
Prodigy 30 points
Part Number: TCA9802

Could you explan input leakage current of SDAA, SCLA ?

1. When VI = VCCA =0 , EN = GND

2. When VI >VCCA, EN = GND

3. When VI <VCCA, EN = GND

Will the leakage change when EN is connect to a very high resistance to GND?

  • 0
    TI__Mastermind 23633 points

    Hi Weilun,

    Your question is pulled from the electrical characteristics portion in the datasheet:

    VI is the input voltage while EN is the voltage on the enable pin. 

    In all three cases, the internal buffer re-driving circuitry is turned off due to EN = GND. 

    Cases 1 and 3 should be about the same input leakage current between -10 uA and +10 uA. For case 2, we do not spec this in the datasheet. The device does have powered-off high impedance I2C bus pins on the A-side. So if a input voltage is present when VCCA < UVLO, it is safe to still have I2C communication present on the A-side. 

    weilun luo said:
    Will the leakage change when EN is connect to a very high resistance to GND?

    We also don't spec the leakage current here when EN in this specific scenario. I would expect the input leakage current on SDAA/SCLA/SDAB/SCLB to change very little, as this is the connection to a high-impedance input internally. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Prodigy 30 points

    If want to put pull low resistor on EN pin, do you have any concern or suggestion? 

    Thank you very much. 

  • 0 in reply to weilun luo
    TI__Mastermind 23633 points

    Weilun,

    The EN pin has a built in pull-up resistor (typical value of 250kohm) to VCCA. If you decide to tie EN to GND via pull-down resistor, you would need to make sure that the pull-down is stronger than 250k. A good value to start with would be something like 10kohm. This would ensure that you bias the EN pin to a low state by overcoming the internal pull-up.

    Regards,

    Tyler