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TCA9534A: Technical Query - TCA9534A

Napa Prasad
Prodigy 60 points

Part Number: TCA9534A
Other Parts Discussed in Thread: TCA6416A, TCAL6408, TCA6408A

Hii Team,

I'm, planning to use TCA9534A in our project. I want the I2C Interface to work at 3.3 V level but few GPIOs at 3.3 V level & few GPIOs at 1.8 level. Will TCA9534A supports this ? 

  • 0
    TI__Guru 61618 points

    Hi Napa,

    The TCA6416A may be able to work here.

    It does not have three separate supply pins, VCC1 = I2C, VCC2 = GPIO 3.3V, VCC3 = GPIO 1.8V. TCA6416A does have 5V tolerant I/O's. So you could set VCCI = 3.3V for I2C, VCCP = 1.8V for GPIO side, then for the GPIO's at 3.3V use a pull-up resistor to 3.3V with open-drain configuration. The device supports voltages above the VCCP supply (5V tolerant I/O's). 

    Regards,

    Tyler

  • 0
    Prodigy 60 points

    Hii Tyler,

    Using TCA9532A, Can I use I2C at 3.3 V, all the GPIOs at 1.8V using open-drain pull up resistor configuration?

    Regards,

    Karthik

  • 0 in reply to Napa Prasad
    TI__Guru 56431 points

    Hi Napa,

    We have received your response and will follow up soon.

    Regards,

    Jack

  • 0 in reply to Napa Prasad
    TI__Guru 61618 points

    Hi Napa,

    The TCA9532A does not exist. I think you mean TCA9534A. 

    If you have VCC = 3.3V, and I2C running at 3.3V with GPIOs running at 1.8V, you will still have any Pxx pin as output sourcing a 3.3V signal. 

    If you use as inputs and pull-up to a 1.8V external supply, the GPIO will sit roughly mid rail on the CMOS input. You can expect a large amount of current consumption when doing so. 

    I really recommend switching to a proper dual supply I/O expander here such as TCA6408A or TCAL6408. 

    Regards,

    Tyler